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[Maria-developers] Rev 2779: Merge in MWL#68: Subquery optimization: Efficient NOT IN execution with NULLs in file:///home/psergey/dev/maria-5.3-subqueries-r7/
by Sergey Petrunya 15 Mar '10

15 Mar '10

At file:///home/psergey/dev/maria-5.3-subqueries-r7/ ------------------------------------------------------------ revno: 2779 [merge] revision-id: psergey(a)askmonty.org-20100315150935-4xm838tskbh9k3ci parent: psergey(a)askmonty.org-20100315063535-jsp4jgya6lfqt8e6 parent: timour(a)sun.com-20100315143456-82d9rq3lbdscbr2n committer: Sergey Petrunya <psergey(a)askmonty.org> branch nick: maria-5.3-subqueries-r7 timestamp: Mon 2010-03-15 18:09:35 +0300 message: Merge in MWL#68: Subquery optimization: Efficient NOT IN execution with NULLs modified: mysql-test/include/mix1.inc sp1f-innodb_mysql.test-20060426055153-mgtahdmgajg7vffqbq4xrmkzbhvanlaz mysql-test/r/index_merge_myisam.result sp1f-index_merge_myisam.r-20060816114353-wd2664hjxwyjdvm4snup647av5fmxfln mysql-test/r/innodb_mysql.result sp1f-innodb_mysql.result-20060426055153-bychbbfnqtvmvrwccwhn24i6yi46uqjv mysql-test/r/myisam_mrr.result myisam_mrr.result-20091215071345-6wadxunod6vi8m48-1 mysql-test/r/ps.result sp1f-ps.result-20040405154119-efxzt5onloys45nfjak4gt44kr4awkdi mysql-test/r/subselect.result sp1f-subselect.result-20020512204640-zgegcsgavnfd7t7eyrf7ibuqomsw7uzo mysql-test/r/subselect3.result sp1f-subselect3.result-20061031174245-v7hvtc7uwevifiq4lziwv5gdcxpeak7t mysql-test/r/subselect3_jcl6.result subselect3_jcl6.resu-20100117143923-cf6j4mu5zzng00u7-1 mysql-test/r/subselect_no_mat.result subselect_no_mat.res-20100117143924-hut18sl9k2c7qdj8-1 mysql-test/r/subselect_no_opts.result subselect_no_opts.re-20100117143925-pabg7o8iyokjlu93-1 mysql-test/r/subselect_no_semijoin.result subselect_no_semijoi-20100117143925-9yfygtcm7fwsuq2p-1 mysql-test/r/subselect_sj.result subselect_sj.result-20100117143926-nrop4ku355g3kv8b-1 mysql-test/r/subselect_sj_jcl6.result subselect_sj_jcl6.re-20100117143928-7vzk51yaf29cdavp-1 mysql-test/t/ps.test sp1f-ps.test-20040405154119-4zqf6po44yypvz5foa2osprg5kb5ok63 mysql-test/t/subselect.test sp1f-subselect.test-20020512204640-lyqrayx6uwsn7zih6y7kerkenuitzbvr mysql-test/t/subselect3.test sp1f-subselect3.test-20061031174245-pcxt5ljylerxhx2jkfhrbqfv5vqcazlz sql/item_cmpfunc.h sp1f-item_cmpfunc.h-19700101030959-pcvbjplo4e4ng7ibynfhcd6pjyem57gr sql/item_subselect.cc sp1f-item_subselect.cc-20020512204640-qep43aqhsfrwkqmrobni6czc3fqj36oo sql/item_subselect.h sp1f-item_subselect.h-20020512204640-qdg77wil56cxyhtc2bjjdrppxq3wqgh3 sql/mysql_priv.h sp1f-mysql_priv.h-19700101030959-4fl65tqpop5zfgxaxkqotu2fa2ree5ci sql/mysqld.cc sp1f-mysqld.cc-19700101030959-zpswdvekpvixxzxf7gdtofzel7nywtfj sql/opt_subselect.cc opt_subselect.cc-20100215190428-nekkl8wisp0k6nlk-1 sql/set_var.cc sp1f-set_var.cc-20020723153119-nwbpg2pwpz55pfw7yfzaxt7hsszzy7y3 sql/sql_class.cc sp1f-sql_class.cc-19700101030959-rpotnweaff2pikkozh3butrf7mv3oero sql/sql_class.h sp1f-sql_class.h-19700101030959-jnqnbrjyqsvgncsibnumsmg3lyi7pa5s sql/sql_select.cc sp1f-sql_select.cc-19700101030959-egb7whpkh76zzvikycs5nsnuviu4fdlb === modified file 'mysql-test/include/mix1.inc' --- a/mysql-test/include/mix1.inc 2009-09-15 06:08:54 +0000 +++ b/mysql-test/include/mix1.inc 2010-03-11 21:43:31 +0000 @@ -1177,8 +1177,11 @@ create table t1 (a bit(1) not null,b int) engine=myisam; create table t2 (c int) engine=innodb; +set @save_optimizer_switch=@@optimizer_switch; +set @@optimizer_switch='partial_match_rowid_merge=off,partial_match_table_scan=off'; explain select b from t1 where a not in (select b from t1,t2 group by a) group by a; +set optimizer_switch=@save_optimizer_switch; DROP TABLE t1,t2; --echo End of 5.0 tests === modified file 'mysql-test/r/index_merge_myisam.result' --- a/mysql-test/r/index_merge_myisam.result 2010-01-17 14:51:10 +0000 +++ b/mysql-test/r/index_merge_myisam.result 2010-03-11 21:43:31 +0000 @@ -1419,19 +1419,19 @@ # select @@optimizer_switch; @@optimizer_switch -index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on +index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on set optimizer_switch='index_merge=off,index_merge_union=off'; select @@optimizer_switch; @@optimizer_switch -index_merge=off,index_merge_union=off,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on +index_merge=off,index_merge_union=off,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on set optimizer_switch='index_merge_union=on'; select @@optimizer_switch; @@optimizer_switch -index_merge=off,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on +index_merge=off,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on set optimizer_switch='default,index_merge_sort_union=off'; select @@optimizer_switch; @@optimizer_switch -index_merge=on,index_merge_union=on,index_merge_sort_union=off,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on +index_merge=on,index_merge_union=on,index_merge_sort_union=off,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on set optimizer_switch=4; ERROR 42000: Variable 'optimizer_switch' can't be set to the value of '4' set optimizer_switch=NULL; @@ -1458,21 +1458,21 @@ set optimizer_switch='index_merge=off,index_merge_union=off,default'; select @@optimizer_switch; @@optimizer_switch -index_merge=off,index_merge_union=off,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on +index_merge=off,index_merge_union=off,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on set optimizer_switch=default; select @@global.optimizer_switch; @@global.optimizer_switch -index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on +index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on set @@global.optimizer_switch=default; select @@global.optimizer_switch; @@global.optimizer_switch -index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on +index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on # # Check index_merge's @@optimizer_switch flags # select @@optimizer_switch; @@optimizer_switch -index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on +index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on create table t0 (a int); insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9); create table t1 (a int, b int, c int, filler char(100), @@ -1582,5 +1582,5 @@ set optimizer_switch=default; show variables like 'optimizer_switch'; Variable_name Value -optimizer_switch index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on +optimizer_switch index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on drop table t0, t1; === modified file 'mysql-test/r/innodb_mysql.result' --- a/mysql-test/r/innodb_mysql.result 2009-12-15 07:16:46 +0000 +++ b/mysql-test/r/innodb_mysql.result 2010-03-11 21:43:31 +0000 @@ -1425,12 +1425,15 @@ # create table t1 (a bit(1) not null,b int) engine=myisam; create table t2 (c int) engine=innodb; +set @save_optimizer_switch=@@optimizer_switch; +set @@optimizer_switch='partial_match_rowid_merge=off,partial_match_table_scan=off'; explain select b from t1 where a not in (select b from t1,t2 group by a) group by a; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE noticed after reading const tables 2 DEPENDENT SUBQUERY t1 system NULL NULL NULL NULL 0 const row not found 2 DEPENDENT SUBQUERY t2 ALL NULL NULL NULL NULL 1 +set optimizer_switch=@save_optimizer_switch; DROP TABLE t1,t2; End of 5.0 tests CREATE TABLE `t2` ( === modified file 'mysql-test/r/myisam_mrr.result' --- a/mysql-test/r/myisam_mrr.result 2010-01-17 14:51:10 +0000 +++ b/mysql-test/r/myisam_mrr.result 2010-03-11 21:43:31 +0000 @@ -394,7 +394,7 @@ # - engine_condition_pushdown does not affect ICP select @@optimizer_switch; @@optimizer_switch -index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on +index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on create table t0 (a int); insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9); create table t1 (a int, b int, key(a)); === modified file 'mysql-test/r/ps.result' --- a/mysql-test/r/ps.result 2009-05-27 15:19:44 +0000 +++ b/mysql-test/r/ps.result 2010-03-11 21:43:31 +0000 @@ -149,6 +149,8 @@ c32 set('monday', 'tuesday', 'wednesday') ) engine = MYISAM ; create table t2 like t1; +set @save_optimizer_switch=@@optimizer_switch; +set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off"; set @stmt= ' explain SELECT (SELECT SUM(c1 + c12 + 0.0) FROM t2 where (t1.c2 - 0e-3) = t2.c2 GROUP BY t1.c15 LIMIT 1) as scalar_s, exists (select 1.0e+0 from t2 where t2.c3 * 9.0000000000 = t1.c4) as exists_s, c5 * 4 in (select c6 + 0.3e+1 from t2) as in_s, (c7 - 4, c8 - 4) in (select c9 + 4.0, c10 + 40e-1 from t2) as in_row_s FROM t1, (select c25 x, c32 y from t2) tt WHERE x * 1 = c25 ' ; prepare stmt1 from @stmt ; execute stmt1 ; @@ -177,6 +179,7 @@ 2 DEPENDENT SUBQUERY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE noticed after reading const tables deallocate prepare stmt1; drop tables t1,t2; +set @@optimizer_switch=@save_optimizer_switch; set @arg00=1; prepare stmt1 from ' create table t1 (m int) as select 1 as m ' ; execute stmt1 ; === modified file 'mysql-test/r/subselect.result' --- a/mysql-test/r/subselect.result 2010-02-17 21:59:41 +0000 +++ b/mysql-test/r/subselect.result 2010-03-11 21:43:31 +0000 @@ -1,4 +1,6 @@ drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t11,t12; +set @save_optimizer_switch=@@optimizer_switch; +set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off"; select (select 2); (select 2) 2 @@ -4803,4 +4805,5 @@ 1 1 DROP TABLE t1; +set @@optimizer_switch=@save_optimizer_switch; End of 5.1 tests. === modified file 'mysql-test/r/subselect3.result' --- a/mysql-test/r/subselect3.result 2010-02-17 10:05:27 +0000 +++ b/mysql-test/r/subselect3.result 2010-03-11 21:43:31 +0000 @@ -63,12 +63,15 @@ select ' ^ This must show 11' Z; Z ^ This must show 11 +set @save_optimizer_switch=@@optimizer_switch; +set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off"; explain extended select a in (select max(ie) from t1 where oref=4 group by grp) from t3; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t3 ALL NULL NULL NULL NULL 2 100.00 2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 6 100.00 Using where; Using temporary; Using filesort Warnings: Note 1003 select <in_optimizer>(`test`.`t3`.`a`,<exists>(select max(`test`.`t1`.`ie`) AS `max(ie)` from `test`.`t1` where (`test`.`t1`.`oref` = 4) group by `test`.`t1`.`grp` having trigcond((<cache>(`test`.`t3`.`a`) = <ref_null_helper>(max(`test`.`t1`.`ie`)))))) AS `a in (select max(ie) from t1 where oref=4 group by grp)` from `test`.`t3` +set @@optimizer_switch=@save_optimizer_switch; drop table t1, t2, t3; create table t1 (a int, oref int, key(a)); insert into t1 values @@ -692,6 +695,8 @@ 2 3 h 3 4 i DROP TABLE t1, t2; +set @save_optimizer_switch=@@optimizer_switch; +set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off"; CREATE TABLE t1 (a int); CREATE TABLE t2 (b int, PRIMARY KEY(b)); INSERT INTO t1 VALUES (1), (NULL), (4); @@ -759,6 +764,7 @@ 1 PRIMARY t1 ALL NULL NULL NULL NULL 4 Using where 2 DEPENDENT SUBQUERY t2 unique_subquery PRIMARY PRIMARY 4 func 1 Using index; Using where DROP TABLE t1, t2; +set @@optimizer_switch=@save_optimizer_switch; CREATE TABLE t1 (a INT); INSERT INTO t1 VALUES(1); CREATE TABLE t2 (placeholder CHAR(11)); @@ -960,7 +966,7 @@ # Baseline: SHOW STATUS LIKE '%Handler_read_rnd_next'; Variable_name Value -Handler_read_rnd_next 17 +Handler_read_rnd_next 18 INSERT INTO t1 VALUES (NULL, NULL); FLUSH STATUS; @@ -977,7 +983,7 @@ # (read record from t1, but do not read from t2) SHOW STATUS LIKE '%Handler_read_rnd_next'; Variable_name Value -Handler_read_rnd_next 18 +Handler_read_rnd_next 19 DROP TABLE t1,t2; End of 5.1 tests CREATE TABLE t1 ( === modified file 'mysql-test/r/subselect3_jcl6.result' --- a/mysql-test/r/subselect3_jcl6.result 2010-02-17 10:47:55 +0000 +++ b/mysql-test/r/subselect3_jcl6.result 2010-03-11 21:43:31 +0000 @@ -67,12 +67,15 @@ select ' ^ This must show 11' Z; Z ^ This must show 11 +set @save_optimizer_switch=@@optimizer_switch; +set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off"; explain extended select a in (select max(ie) from t1 where oref=4 group by grp) from t3; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t3 ALL NULL NULL NULL NULL 2 100.00 2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 6 100.00 Using where; Using temporary; Using filesort Warnings: Note 1003 select <in_optimizer>(`test`.`t3`.`a`,<exists>(select max(`test`.`t1`.`ie`) AS `max(ie)` from `test`.`t1` where (`test`.`t1`.`oref` = 4) group by `test`.`t1`.`grp` having trigcond((<cache>(`test`.`t3`.`a`) = <ref_null_helper>(max(`test`.`t1`.`ie`)))))) AS `a in (select max(ie) from t1 where oref=4 group by grp)` from `test`.`t3` +set @@optimizer_switch=@save_optimizer_switch; drop table t1, t2, t3; create table t1 (a int, oref int, key(a)); insert into t1 values @@ -696,6 +699,8 @@ 2 3 h 3 4 i DROP TABLE t1, t2; +set @save_optimizer_switch=@@optimizer_switch; +set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off"; CREATE TABLE t1 (a int); CREATE TABLE t2 (b int, PRIMARY KEY(b)); INSERT INTO t1 VALUES (1), (NULL), (4); @@ -763,6 +768,7 @@ 1 PRIMARY t1 ALL NULL NULL NULL NULL 4 Using where 2 DEPENDENT SUBQUERY t2 unique_subquery PRIMARY PRIMARY 4 func 1 Using index; Using where DROP TABLE t1, t2; +set @@optimizer_switch=@save_optimizer_switch; CREATE TABLE t1 (a INT); INSERT INTO t1 VALUES(1); CREATE TABLE t2 (placeholder CHAR(11)); @@ -964,7 +970,7 @@ # Baseline: SHOW STATUS LIKE '%Handler_read_rnd_next'; Variable_name Value -Handler_read_rnd_next 17 +Handler_read_rnd_next 18 INSERT INTO t1 VALUES (NULL, NULL); FLUSH STATUS; @@ -981,7 +987,7 @@ # (read record from t1, but do not read from t2) SHOW STATUS LIKE '%Handler_read_rnd_next'; Variable_name Value -Handler_read_rnd_next 18 +Handler_read_rnd_next 19 DROP TABLE t1,t2; End of 5.1 tests CREATE TABLE t1 ( === modified file 'mysql-test/r/subselect_no_mat.result' --- a/mysql-test/r/subselect_no_mat.result 2010-02-21 07:33:54 +0000 +++ b/mysql-test/r/subselect_no_mat.result 2010-03-11 21:43:31 +0000 @@ -1,8 +1,10 @@ show variables like 'optimizer_switch'; Variable_name Value -optimizer_switch index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on +optimizer_switch index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on set optimizer_switch='materialization=off'; drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t11,t12; +set @save_optimizer_switch=@@optimizer_switch; +set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off"; select (select 2); (select 2) 2 @@ -4807,8 +4809,9 @@ 1 1 DROP TABLE t1; +set @@optimizer_switch=@save_optimizer_switch; End of 5.1 tests. set optimizer_switch=default; show variables like 'optimizer_switch'; Variable_name Value -optimizer_switch index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on +optimizer_switch index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on === modified file 'mysql-test/r/subselect_no_opts.result' --- a/mysql-test/r/subselect_no_opts.result 2010-02-21 07:33:54 +0000 +++ b/mysql-test/r/subselect_no_opts.result 2010-03-11 21:43:31 +0000 @@ -1,8 +1,10 @@ show variables like 'optimizer_switch'; Variable_name Value -optimizer_switch index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on +optimizer_switch index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on set optimizer_switch='materialization=off,semijoin=off'; drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t11,t12; +set @save_optimizer_switch=@@optimizer_switch; +set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off"; select (select 2); (select 2) 2 @@ -4807,8 +4809,9 @@ 1 1 DROP TABLE t1; +set @@optimizer_switch=@save_optimizer_switch; End of 5.1 tests. set optimizer_switch=default; show variables like 'optimizer_switch'; Variable_name Value -optimizer_switch index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on +optimizer_switch index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on === modified file 'mysql-test/r/subselect_no_semijoin.result' --- a/mysql-test/r/subselect_no_semijoin.result 2010-02-21 07:33:54 +0000 +++ b/mysql-test/r/subselect_no_semijoin.result 2010-03-11 21:43:31 +0000 @@ -1,8 +1,10 @@ show variables like 'optimizer_switch'; Variable_name Value -optimizer_switch index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on +optimizer_switch index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on set optimizer_switch='semijoin=off'; drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t11,t12; +set @save_optimizer_switch=@@optimizer_switch; +set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off"; select (select 2); (select 2) 2 @@ -4807,8 +4809,9 @@ 1 1 DROP TABLE t1; +set @@optimizer_switch=@save_optimizer_switch; End of 5.1 tests. set optimizer_switch=default; show variables like 'optimizer_switch'; Variable_name Value -optimizer_switch index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on +optimizer_switch index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on === modified file 'mysql-test/r/subselect_sj.result' --- a/mysql-test/r/subselect_sj.result 2010-03-15 06:32:54 +0000 +++ b/mysql-test/r/subselect_sj.result 2010-03-15 15:09:35 +0000 @@ -202,39 +202,39 @@ select @@optimizer_switch; @@optimizer_switch -index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on +index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on set optimizer_switch='default,materialization=off'; select @@optimizer_switch; @@optimizer_switch -index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=off,semijoin=on +index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=off,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on set optimizer_switch='default,semijoin=off'; select @@optimizer_switch; @@optimizer_switch -index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=off +index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=off,partial_match_rowid_merge=on,partial_match_table_scan=on set optimizer_switch='default,loosescan=off'; select @@optimizer_switch; @@optimizer_switch -index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=on,semijoin=on +index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on set optimizer_switch='default,semijoin=off,materialization=off'; select @@optimizer_switch; @@optimizer_switch -index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=off,semijoin=off +index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=off,semijoin=off,partial_match_rowid_merge=on,partial_match_table_scan=on set optimizer_switch='default,materialization=off,semijoin=off'; select @@optimizer_switch; @@optimizer_switch -index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=off,semijoin=off +index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=off,semijoin=off,partial_match_rowid_merge=on,partial_match_table_scan=on set optimizer_switch='default,semijoin=off,materialization=off,loosescan=off'; select @@optimizer_switch; @@optimizer_switch -index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=off,semijoin=off +index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=off,semijoin=off,partial_match_rowid_merge=on,partial_match_table_scan=on set optimizer_switch='default,semijoin=off,loosescan=off'; select @@optimizer_switch; @@optimizer_switch -index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=on,semijoin=off +index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=on,semijoin=off,partial_match_rowid_merge=on,partial_match_table_scan=on set optimizer_switch='default,materialization=off,loosescan=off'; select @@optimizer_switch; @@optimizer_switch -index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=off,semijoin=on +index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=off,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on set optimizer_switch=default; drop table t0, t1, t2; drop table t10, t11, t12; === modified file 'mysql-test/r/subselect_sj_jcl6.result' --- a/mysql-test/r/subselect_sj_jcl6.result 2010-03-15 06:32:54 +0000 +++ b/mysql-test/r/subselect_sj_jcl6.result 2010-03-15 15:09:35 +0000 @@ -206,39 +206,39 @@ select @@optimizer_switch; @@optimizer_switch -index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on +index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on set optimizer_switch='default,materialization=off'; select @@optimizer_switch; @@optimizer_switch -index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=off,semijoin=on +index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=off,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on set optimizer_switch='default,semijoin=off'; select @@optimizer_switch; @@optimizer_switch -index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=off +index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=off,partial_match_rowid_merge=on,partial_match_table_scan=on set optimizer_switch='default,loosescan=off'; select @@optimizer_switch; @@optimizer_switch -index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=on,semijoin=on +index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on set optimizer_switch='default,semijoin=off,materialization=off'; select @@optimizer_switch; @@optimizer_switch -index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=off,semijoin=off +index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=off,semijoin=off,partial_match_rowid_merge=on,partial_match_table_scan=on set optimizer_switch='default,materialization=off,semijoin=off'; select @@optimizer_switch; @@optimizer_switch -index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=off,semijoin=off +index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=off,semijoin=off,partial_match_rowid_merge=on,partial_match_table_scan=on set optimizer_switch='default,semijoin=off,materialization=off,loosescan=off'; select @@optimizer_switch; @@optimizer_switch -index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=off,semijoin=off +index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=off,semijoin=off,partial_match_rowid_merge=on,partial_match_table_scan=on set optimizer_switch='default,semijoin=off,loosescan=off'; select @@optimizer_switch; @@optimizer_switch -index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=on,semijoin=off +index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=on,semijoin=off,partial_match_rowid_merge=on,partial_match_table_scan=on set optimizer_switch='default,materialization=off,loosescan=off'; select @@optimizer_switch; @@optimizer_switch -index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=off,semijoin=on +index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=off,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on set optimizer_switch=default; drop table t0, t1, t2; drop table t10, t11, t12; === modified file 'mysql-test/t/ps.test' --- a/mysql-test/t/ps.test 2009-05-27 15:19:44 +0000 +++ b/mysql-test/t/ps.test 2010-03-11 21:43:31 +0000 @@ -163,6 +163,9 @@ ) engine = MYISAM ; create table t2 like t1; +set @save_optimizer_switch=@@optimizer_switch; +set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off"; + set @stmt= ' explain SELECT (SELECT SUM(c1 + c12 + 0.0) FROM t2 where (t1.c2 - 0e-3) = t2.c2 GROUP BY t1.c15 LIMIT 1) as scalar_s, exists (select 1.0e+0 from t2 where t2.c3 * 9.0000000000 = t1.c4) as exists_s, c5 * 4 in (select c6 + 0.3e+1 from t2) as in_s, (c7 - 4, c8 - 4) in (select c9 + 4.0, c10 + 40e-1 from t2) as in_row_s FROM t1, (select c25 x, c32 y from t2) tt WHERE x * 1 = c25 ' ; prepare stmt1 from @stmt ; execute stmt1 ; @@ -171,6 +174,8 @@ deallocate prepare stmt1; drop tables t1,t2; +set @@optimizer_switch=@save_optimizer_switch; + # # parameters from variables (for field creation) # === modified file 'mysql-test/t/subselect.test' --- a/mysql-test/t/subselect.test 2010-01-17 20:52:20 +0000 +++ b/mysql-test/t/subselect.test 2010-03-11 21:43:31 +0000 @@ -11,6 +11,9 @@ drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t11,t12; --enable_warnings +set @save_optimizer_switch=@@optimizer_switch; +set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off"; + select (select 2); explain extended select (select 2); SELECT (SELECT 1) UNION SELECT (SELECT 2); @@ -4061,4 +4064,6 @@ (SELECT LAST_INSERT_ID() FROM t1 ORDER BY MIN(a) ASC LIMIT 1); DROP TABLE t1; +set @@optimizer_switch=@save_optimizer_switch; + --echo End of 5.1 tests. === modified file 'mysql-test/t/subselect3.test' --- a/mysql-test/t/subselect3.test 2010-01-17 14:51:10 +0000 +++ b/mysql-test/t/subselect3.test 2010-03-11 21:43:31 +0000 @@ -59,9 +59,13 @@ show status like 'Handler_read_rnd_next'; select ' ^ This must show 11' Z; +set @save_optimizer_switch=@@optimizer_switch; +set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off"; + # This must show trigcond: explain extended select a in (select max(ie) from t1 where oref=4 group by grp) from t3; +set @@optimizer_switch=@save_optimizer_switch; drop table t1, t2, t3; # @@ -529,6 +533,9 @@ DROP TABLE t1, t2; +# The next three test cases must be executed with the IN=>EXISTS strategy +set @save_optimizer_switch=@@optimizer_switch; +set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off"; # # Bug #27870: crash of an equijoin query with WHERE condition containing @@ -588,6 +595,8 @@ DROP TABLE t1, t2; +set @@optimizer_switch=@save_optimizer_switch; + # # Bug #34763: item_subselect.cc:1235:Item_in_subselect::row_value_transformer: # Assertion failed, unexpected error message: === modified file 'sql/item_cmpfunc.h' --- a/sql/item_cmpfunc.h 2010-03-13 20:04:52 +0000 +++ b/sql/item_cmpfunc.h 2010-03-15 14:34:56 +0000 @@ -350,6 +350,7 @@ CHARSET_INFO *compare_collation() { return cmp.cmp_collation.collation; } uint decimal_precision() const { return 1; } void top_level_item() { abort_on_null= TRUE; } + Arg_comparator *get_comparator() { return &cmp; } friend class Arg_comparator; }; === modified file 'sql/item_subselect.cc' --- a/sql/item_subselect.cc 2010-02-21 06:32:23 +0000 +++ b/sql/item_subselect.cc 2010-03-09 10:14:06 +0000 @@ -138,6 +138,7 @@ left_expr_cache= NULL; } first_execution= TRUE; + is_constant= FALSE; Item_subselect::cleanup(); DBUG_VOID_RETURN; } @@ -449,8 +450,10 @@ int res; if (thd->is_error()) - /* Do not execute subselect in case of a fatal error */ + { + /* Do not execute subselect in case of a fatal error */ return 1; + } /* Simulate a failure in sub-query execution. Used to test e.g. out of memory or query being killed conditions. @@ -475,9 +478,6 @@ bool Item_in_subselect::exec() { DBUG_ENTER("Item_in_subselect::exec"); - DBUG_ASSERT(exec_method != MATERIALIZATION || - (exec_method == MATERIALIZATION && - engine->engine_type() == subselect_engine::HASH_SJ_ENGINE)); /* Initialize the cache of the left predicate operand. This has to be done as late as now, because Cached_item directly contains a resolved field (not @@ -493,14 +493,14 @@ if (!left_expr_cache && exec_method == MATERIALIZATION) init_left_expr_cache(); - /* If the new left operand is already in the cache, reuse the old result. */ - if (left_expr_cache && test_if_item_cache_changed(*left_expr_cache) < 0) - { - /* Always compute IN for the first row as the cache is not valid for it. */ - if (!first_execution) - DBUG_RETURN(FALSE); - first_execution= FALSE; - } + /* + If the new left operand is already in the cache, reuse the old result. + Use the cached result only if this is not the first execution of IN + because the cache is not valid for the first execution. + */ + if (!first_execution && left_expr_cache && + test_if_item_cache_changed(*left_expr_cache) < 0) + DBUG_RETURN(FALSE); /* The exec() method below updates item::value, and item::null_value, thus if @@ -910,8 +910,8 @@ Item_in_subselect::Item_in_subselect(Item * left_exp, st_select_lex *select_lex): Item_exists_subselect(), left_expr_cache(0), first_execution(TRUE), - optimizer(0), pushed_cond_guards(NULL), exec_method(NOT_TRANSFORMED), - upper_item(0) + is_constant(FALSE), optimizer(0), pushed_cond_guards(NULL), + exec_method(NOT_TRANSFORMED), upper_item(0) { DBUG_ENTER("Item_in_subselect::Item_in_subselect"); left_expr= left_exp; @@ -1105,6 +1105,8 @@ { DBUG_ASSERT(fixed == 1); null_value= 0; + if (is_constant) + return value; if (exec()) { reset(); @@ -1571,9 +1573,9 @@ DBUG_ENTER("Item_in_subselect::row_value_transformer"); // psergey: duplicated_subselect_card_check - if (select_lex->item_list.elements != left_expr->cols()) + if (select_lex->item_list.elements != cols_num) { - my_error(ER_OPERAND_COLUMNS, MYF(0), left_expr->cols()); + my_error(ER_OPERAND_COLUMNS, MYF(0), cols_num); DBUG_RETURN(RES_ERROR); } @@ -1980,17 +1982,69 @@ bool Item_in_subselect::fix_fields(THD *thd_arg, Item **ref) { - bool result = 0; + uint outer_cols_num; + List<Item> *inner_cols; if (exec_method == SEMI_JOIN) return !( (*ref)= new Item_int(1)); - if (thd_arg->lex->view_prepare_mode && left_expr && !left_expr->fixed) - result = left_expr->fix_fields(thd_arg, &left_expr); - - return result || Item_subselect::fix_fields(thd_arg, ref); + /* + Check if the outer and inner IN operands match in those cases when we + will not perform IN=>EXISTS transformation. Currently this is when we + use subquery materialization. + + The condition below is true when this method was called recursively from + inside JOIN::prepare for the JOIN object created by the call chain + Item_subselect::fix_fields -> subselect_single_select_engine::prepare, + which creates a JOIN object for the subquery and calls JOIN::prepare for + the JOIN of the subquery. + Notice that in some cases, this doesn't happen, and the check_cols() + test for each Item happens later in + Item_in_subselect::row_value_in_to_exists_transformer. + The reason for this mess is that our JOIN::prepare phase works top-down + instead of bottom-up, so we first do name resoluton and semantic checks + for the outer selects, then for the inner. + */ + if (engine && + engine->engine_type() == subselect_engine::SINGLE_SELECT_ENGINE && + ((subselect_single_select_engine*)engine)->join) + { + outer_cols_num= left_expr->cols(); + + if (unit->is_union()) + inner_cols= &(unit->types); + else + inner_cols= &(unit->first_select()->item_list); + if (outer_cols_num != inner_cols->elements) + { + my_error(ER_OPERAND_COLUMNS, MYF(0), outer_cols_num); + return TRUE; + } + if (outer_cols_num > 1) + { + List_iterator<Item> inner_col_it(*inner_cols); + Item *inner_col; + for (uint i= 0; i < outer_cols_num; i++) + { + inner_col= inner_col_it++; + if (inner_col->check_cols(left_expr->element_index(i)->cols())) + return TRUE; + } + } + } + + if (thd_arg->lex->view_prepare_mode && left_expr && !left_expr->fixed && + left_expr->fix_fields(thd_arg, &left_expr)) + return TRUE; + if (Item_subselect::fix_fields(thd_arg, ref)) + return TRUE; + + fixed= TRUE; + + return FALSE; } + void Item_in_subselect::fix_after_pullout(st_select_lex *new_parent, Item **ref) { left_expr->fix_after_pullout(new_parent, &left_expr); @@ -2267,10 +2321,9 @@ void subselect_uniquesubquery_engine::cleanup() { DBUG_ENTER("subselect_uniquesubquery_engine::cleanup"); - /* - subselect_uniquesubquery_engine have not 'result' assigbed, so we do not - cleanup() it - */ + /* Tell handler we don't need the index anymore */ + if (tab->table->file->inited) + tab->table->file->ha_index_end(); DBUG_VOID_RETURN; } @@ -2291,7 +2344,7 @@ Create and prepare the JOIN object that represents the query execution plan for the subquery. - @detail + @details This method is called from Item_subselect::fix_fields. For prepared statements it is called both during the PREPARE and EXECUTE phases in the following ways: @@ -2593,14 +2646,23 @@ for (;;) { error=table->file->ha_rnd_next(table->record[0]); - if (error && error != HA_ERR_END_OF_FILE) - { - error= report_error(table, error); - break; + if (error) { + if (error == HA_ERR_RECORD_DELETED) + { + error= 0; + continue; + } + if (error == HA_ERR_END_OF_FILE) + { + error= 0; + break; + } + else + { + error= report_error(table, error); + break; + } } - /* No more rows */ - if (table->status) - break; if (!cond || cond->val_int()) { @@ -2711,6 +2773,56 @@ /* + @retval 1 A NULL was found in the outer reference, index lookup is + not applicable, the outer ref is unsusable as a lookup key, + use some other method to find a match. + @retval 0 The outer ref was copied into an index lookup key. + @retval -1 The outer ref cannot possibly match any row, IN is FALSE. +*/ +/* TIMOUR: this method is a variant of copy_ref_key(), needs refactoring. */ + +int subselect_uniquesubquery_engine::copy_ref_key_simple() +{ + for (store_key **copy= tab->ref.key_copy ; *copy ; copy++) + { + enum store_key::store_key_result store_res; + store_res= (*copy)->copy(); + tab->ref.key_err= store_res; + + /* + When there is a NULL part in the key we don't need to make index + lookup for such key thus we don't need to copy whole key. + If we later should do a sequential scan return OK. Fail otherwise. + + See also the comment for the subselect_uniquesubquery_engine::exec() + function. + */ + null_keypart= (*copy)->null_key; + if (null_keypart) + return 1; + + /* + Check if the error is equal to STORE_KEY_FATAL. This is not expressed + using the store_key::store_key_result enum because ref.key_err is a + boolean and we want to detect both TRUE and STORE_KEY_FATAL from the + space of the union of the values of [TRUE, FALSE] and + store_key::store_key_result. + TODO: fix the variable an return types. + */ + if (store_res == store_key::STORE_KEY_FATAL) + { + /* + Error converting the left IN operand to the column type of the right + IN operand. + */ + return -1; + } + } + return 0; +} + + +/* Execute subselect SYNOPSIS @@ -2750,7 +2862,13 @@ /* TODO: change to use of 'full_scan' here? */ if (copy_ref_key()) + { + /* + TIMOUR: copy_ref_key() == 1 means NULL result, not error, why return 1? + Check who reiles on this result. + */ DBUG_RETURN(1); + } if (table->status) { /* @@ -2791,6 +2909,46 @@ } +/* + TIMOUR: write comment +*/ + +int subselect_uniquesubquery_engine::index_lookup() +{ + DBUG_ENTER("subselect_uniquesubquery_engine::index_lookup"); + int error; + TABLE *table= tab->table; + + if (!table->file->inited) + table->file->ha_index_init(tab->ref.key, 0); + error= table->file->ha_index_read_map(table->record[0], + tab->ref.key_buff, + make_prev_keypart_map(tab-> + ref.key_parts), + HA_READ_KEY_EXACT); + DBUG_PRINT("info", ("lookup result: %i", error)); + + if (error && error != HA_ERR_KEY_NOT_FOUND && error != HA_ERR_END_OF_FILE) + { + /* + TIMOUR: I don't understand at all when do we need to call report_error. + In most places where we access an index, we don't do this. Why here? + */ + error= report_error(table, error); + DBUG_RETURN(error); + } + + table->null_row= 0; + if (!error && (!cond || cond->val_int())) + ((Item_in_subselect *) item)->value= 1; + else + ((Item_in_subselect *) item)->value= 0; + + DBUG_RETURN(0); +} + + + subselect_uniquesubquery_engine::~subselect_uniquesubquery_engine() { /* Tell handler we don't need the index anymore */ @@ -3225,6 +3383,7 @@ bool subselect_uniquesubquery_engine::no_tables() { /* returning value is correct, but this method should never be called */ + DBUG_ASSERT(FALSE); return 0; } @@ -3235,16 +3394,259 @@ /** + Check if an IN predicate should be executed via partial matching using + only schema information. + + @details + This test essentially has three results: + - partial matching is applicable, but cannot be executed due to a + limitation in the total number of indexes, as a result we can't + use subquery materialization at all. + - partial matching is either applicable or not, and this can be + determined by looking at 'this->max_keys'. + If max_keys > 1, then we need partial matching because there are + more indexes than just the one we use during materialization to + remove duplicates. + + @note + TIMOUR: The schema-based analysis for partial matching can be done once for + prepared statement and remembered. It is done here to remove the need to + save/restore all related variables between each re-execution, thus making + the code simpler. + + @retval PARTIAL_MATCH if a partial match should be used + @retval COMPLETE_MATCH if a complete match (index lookup) should be used +*/ + +subselect_hash_sj_engine::exec_strategy +subselect_hash_sj_engine::get_strategy_using_schema() +{ + Item_in_subselect *item_in= (Item_in_subselect *) item; + + if (item_in->is_top_level_item()) + return COMPLETE_MATCH; + else + { + List_iterator<Item> inner_col_it(*item_in->unit->get_unit_column_types()); + Item *outer_col, *inner_col; + + for (uint i= 0; i < item_in->left_expr->cols(); i++) + { + outer_col= item_in->left_expr->element_index(i); + inner_col= inner_col_it++; + + if (!inner_col->maybe_null && !outer_col->maybe_null) + bitmap_set_bit(&non_null_key_parts, i); + else + { + bitmap_set_bit(&partial_match_key_parts, i); + ++count_partial_match_columns; + } + } + } + + /* If no column contains NULLs use regular hash index lookups. */ + if (count_partial_match_columns) + return PARTIAL_MATCH; + return COMPLETE_MATCH; +} + + +/** + Test whether an IN predicate must be computed via partial matching + based on the NULL statistics for each column of a materialized subquery. + + @details The procedure analyzes column NULL statistics, updates the + matching type of columns that cannot be NULL or that contain only NULLs. + Based on this, the procedure determines the final execution strategy for + the [NOT] IN predicate. + + @retval PARTIAL_MATCH if a partial match should be used + @retval COMPLETE_MATCH if a complete match (index lookup) should be used +*/ + +subselect_hash_sj_engine::exec_strategy +subselect_hash_sj_engine::get_strategy_using_data() +{ + Item_in_subselect *item_in= (Item_in_subselect *) item; + select_materialize_with_stats *result_sink= + (select_materialize_with_stats *) result; + Item *outer_col; + + /* + If we already determined that a complete match is enough based on schema + information, nothing can be better. + */ + if (strategy == COMPLETE_MATCH) + return COMPLETE_MATCH; + + for (uint i= 0; i < item_in->left_expr->cols(); i++) + { + if (!bitmap_is_set(&partial_match_key_parts, i)) + continue; + outer_col= item_in->left_expr->element_index(i); + /* + If column 'i' doesn't contain NULLs, and the corresponding outer reference + cannot have a NULL value, then 'i' is a non-nullable column. + */ + if (result_sink->get_null_count_of_col(i) == 0 && !outer_col->maybe_null) + { + bitmap_clear_bit(&partial_match_key_parts, i); + bitmap_set_bit(&non_null_key_parts, i); + --count_partial_match_columns; + } + if (result_sink->get_null_count_of_col(i) == + tmp_table->file->stats.records) + ++count_null_only_columns; + } + + /* If no column contains NULLs use regular hash index lookups. */ + if (!count_partial_match_columns) + return COMPLETE_MATCH; + return PARTIAL_MATCH; +} + + +void +subselect_hash_sj_engine::choose_partial_match_strategy( + bool has_non_null_key, bool has_covering_null_row, + MY_BITMAP *partial_match_key_parts) +{ + size_t pm_buff_size; + + DBUG_ASSERT(strategy == PARTIAL_MATCH); + /* + Choose according to global optimizer switch. If only one of the switches is + 'ON', then the remaining strategy is the only possible one. The only cases + when this will be overriden is when the total size of all buffers for the + merge strategy is bigger than the 'rowid_merge_buff_size' system variable, + or if there isn't enough physical memory to allocate the buffers. + */ + if (!optimizer_flag(thd, OPTIMIZER_SWITCH_PARTIAL_MATCH_ROWID_MERGE) && + optimizer_flag(thd, OPTIMIZER_SWITCH_PARTIAL_MATCH_TABLE_SCAN)) + strategy= PARTIAL_MATCH_SCAN; + else if + ( optimizer_flag(thd, OPTIMIZER_SWITCH_PARTIAL_MATCH_ROWID_MERGE) && + !optimizer_flag(thd, OPTIMIZER_SWITCH_PARTIAL_MATCH_TABLE_SCAN)) + strategy= PARTIAL_MATCH_MERGE; + + /* + If both switches are ON, or both are OFF, we interpret that as "let the + optimizer decide". Perform a cost based choice between the two partial + matching strategies. + */ + /* + TIMOUR: the above interpretation of the switch values could be changed to: + - if both are ON - let the optimizer decide, + - if both are OFF - do not use partial matching, therefore do not use + materialization in non-top-level predicates. + The problem with this is that we know for sure if we need partial matching + only after the subquery is materialized, and this is too late to revert to + the IN=>EXISTS strategy. + */ + if (strategy == PARTIAL_MATCH) + { + /* + TIMOUR: Currently we use a super simplistic measure. This will be + addressed in a separate task. + */ + if (tmp_table->file->stats.records < 100) + strategy= PARTIAL_MATCH_SCAN; + else + strategy= PARTIAL_MATCH_MERGE; + } + + /* Check if there is enough memory for the rowid merge strategy. */ + if (strategy == PARTIAL_MATCH_MERGE) + { + pm_buff_size= rowid_merge_buff_size(has_non_null_key, + has_covering_null_row, + partial_match_key_parts); + if (pm_buff_size > thd->variables.rowid_merge_buff_size) + strategy= PARTIAL_MATCH_SCAN; + } +} + + +/* + Compute the memory size of all buffers proportional to the number of rows + in tmp_table. + + @details + If the result is bigger than thd->variables.rowid_merge_buff_size, partial + matching via merging is not applicable. +*/ + +size_t subselect_hash_sj_engine::rowid_merge_buff_size( + bool has_non_null_key, bool has_covering_null_row, + MY_BITMAP *partial_match_key_parts) +{ + size_t buff_size; /* Total size of all buffers used by partial matching. */ + ha_rows row_count= tmp_table->file->stats.records; + uint rowid_length= tmp_table->file->ref_length; + select_materialize_with_stats *result_sink= + (select_materialize_with_stats *) result; + + /* Size of the subselect_rowid_merge_engine::row_num_to_rowid buffer. */ + buff_size= row_count * rowid_length * sizeof(uchar); + + if (has_non_null_key) + { + /* Add the size of Ordered_key::key_buff of the only non-NULL key. */ + buff_size+= row_count * sizeof(rownum_t); + } + + if (!has_covering_null_row) + { + for (uint i= 0; i < partial_match_key_parts->n_bits; i++) + { + if (!bitmap_is_set(partial_match_key_parts, i) || + result_sink->get_null_count_of_col(i) == row_count) + continue; /* In these cases we wouldn't construct Ordered keys. */ + + /* Add the size of Ordered_key::key_buff */ + buff_size+= (row_count - result_sink->get_null_count_of_col(i)) * + sizeof(rownum_t); + /* Add the size of Ordered_key::null_key */ + buff_size+= bitmap_buffer_size(result_sink->get_max_null_of_col(i)); + } + } + + return buff_size; +} + + +/* + Initialize a MY_BITMAP with a buffer allocated on the current + memory root. + TIMOUR: move to bitmap C file? +*/ + +static my_bool +bitmap_init_memroot(MY_BITMAP *map, uint n_bits, MEM_ROOT *mem_root) +{ + my_bitmap_map *bitmap_buf; + + if (!(bitmap_buf= (my_bitmap_map*) alloc_root(mem_root, + bitmap_buffer_size(n_bits))) || + bitmap_init(map, bitmap_buf, n_bits, FALSE)) + return TRUE; + bitmap_clear_all(map); + return FALSE; +} + + +/** Create all structures needed for IN execution that can live between PS reexecution. - @detail + @param tmp_columns the items that produce the data for the temp table + + @details - Create a temporary table to store the result of the IN subquery. The temporary table has one hash index on all its columns. - Create a new result sink that sends the result stream of the subquery to the temporary table, - - Create and initialize a new JOIN_TAB, and TABLE_REF objects to perform - lookups into the indexed temporary table. @notice: Currently Item_subselect::init() already chooses and creates at parse @@ -3256,71 +3658,178 @@ bool subselect_hash_sj_engine::init_permanent(List<Item> *tmp_columns) { - /* The result sink where we will materialize the subquery result. */ - select_union *tmp_result_sink; - /* The table into which the subquery is materialized. */ - TABLE *tmp_table; - KEY *tmp_key; /* The only index on the temporary table. */ - uint tmp_key_parts; /* Number of keyparts in tmp_key. */ - Item_in_subselect *item_in= (Item_in_subselect *) item; + /* Options to create_tmp_table. */ + ulonglong tmp_create_options= thd->options | TMP_TABLE_ALL_COLUMNS; + /* | TMP_TABLE_FORCE_MYISAM; TIMOUR: force MYISAM */ DBUG_ENTER("subselect_hash_sj_engine::init_permanent"); - /* 1. Create/initialize materialization related objects. */ + if (bitmap_init_memroot(&non_null_key_parts, tmp_columns->elements, + thd->mem_root) || + bitmap_init_memroot(&partial_match_key_parts, tmp_columns->elements, + thd->mem_root)) + DBUG_RETURN(TRUE); /* Create and initialize a select result interceptor that stores the result stream in a temporary table. The temporary table itself is managed (created/filled/etc) internally by the interceptor. */ - if (!(tmp_result_sink= new select_union)) - DBUG_RETURN(TRUE); - if (tmp_result_sink->create_result_table( - thd, tmp_columns, TRUE, - thd->options | TMP_TABLE_ALL_COLUMNS, +/* + TIMOUR: + Select a more efficient result sink when we know there is no need to collect + data statistics. + + if (strategy == COMPLETE_MATCH) + { + if (!(result= new select_union)) + DBUG_RETURN(TRUE); + } + else if (strategy == PARTIAL_MATCH) + { + if (!(result= new select_materialize_with_stats)) + DBUG_RETURN(TRUE); + } +*/ + if (!(result= new select_materialize_with_stats)) + DBUG_RETURN(TRUE); + + if (((select_union*) result)->create_result_table( + thd, tmp_columns, TRUE, tmp_create_options, "materialized subselect", TRUE)) DBUG_RETURN(TRUE); - tmp_table= tmp_result_sink->table; - tmp_key= tmp_table->key_info; - tmp_key_parts= tmp_key->key_parts; + tmp_table= ((select_union*) result)->table; /* - If the subquery has blobs, or the total key lenght is bigger than some - length, then the created index cannot be used for lookups and we - can't use hash semi join. If this is the case, delete the temporary - table since it will not be used, and tell the caller we failed to - initialize the engine. + If the subquery has blobs, or the total key lenght is bigger than + some length, or the total number of key parts is more than the + allowed maximum (currently MAX_REF_PARTS == 16), then the created + index cannot be used for lookups and we can't use hash semi + join. If this is the case, delete the temporary table since it + will not be used, and tell the caller we failed to initialize the + engine. */ if (tmp_table->s->keys == 0) { -#ifndef DBUG_OFF - handlerton *tmp_table_hton= tmp_table->s->db_type(); -#ifdef USE_MARIA_FOR_TMP_TABLES - DBUG_ASSERT(tmp_table_hton == maria_hton); -#else - DBUG_ASSERT(tmp_table_hton == myisam_hton); -#endif -#endif DBUG_ASSERT( tmp_table->s->uniques || tmp_table->key_info->key_length >= tmp_table->file->max_key_length() || tmp_table->key_info->key_parts > tmp_table->file->max_key_parts()); free_tmp_table(thd, tmp_table); + tmp_table= NULL; delete result; result= NULL; DBUG_RETURN(TRUE); } - result= tmp_result_sink; /* Make sure there is only one index on the temp table, and it doesn't have the extra key part created when s->uniques > 0. */ - DBUG_ASSERT(tmp_table->s->keys == 1 && tmp_columns->elements == tmp_key_parts); - - - /* 2. Create/initialize execution related objects. */ + DBUG_ASSERT(tmp_table->s->keys == 1 && + ((Item_in_subselect *) item)->left_expr->cols() == + tmp_table->key_info->key_parts); + + if (make_semi_join_conds() || + /* A unique_engine is used both for complete and partial matching. */ + !(lookup_engine= make_unique_engine())) + DBUG_RETURN(TRUE); + + DBUG_RETURN(FALSE); +} + + +/* + Create an artificial condition to post-filter those rows matched by index + lookups that cannot be distinguished by the index lookup procedure. + + @notes + The need for post-filtering may occur e.g. because of + truncation. Prepared statements execution requires that fix_fields is + called for every execution. In order to call fix_fields we need to + create a Name_resolution_context and a corresponding TABLE_LIST for + the temporary table for the subquery, so that all column references + to the materialized subquery table can be resolved correctly. + + @returns + @retval TRUE memory allocation error occurred + @retval FALSE the conditions were created and resolved (fixed) +*/ + +bool subselect_hash_sj_engine::make_semi_join_conds() +{ + /* + Table reference for tmp_table that is used to resolve column references + (Item_fields) to columns in tmp_table. + */ + TABLE_LIST *tmp_table_ref; + /* Name resolution context for all tmp_table columns created below. */ + Name_resolution_context *context; + Item_in_subselect *item_in= (Item_in_subselect *) item; + + DBUG_ENTER("subselect_hash_sj_engine::make_semi_join_conds"); + DBUG_ASSERT(semi_join_conds == NULL); + + if (!(semi_join_conds= new Item_cond_and)) + DBUG_RETURN(TRUE); + + if (!(tmp_table_ref= (TABLE_LIST*) thd->alloc(sizeof(TABLE_LIST)))) + DBUG_RETURN(TRUE); + + tmp_table_ref->init_one_table("", "materialized subselect", TL_READ); + tmp_table_ref->table= tmp_table; + + context= new Name_resolution_context; + context->init(); + context->first_name_resolution_table= + context->last_name_resolution_table= tmp_table_ref; + + for (uint i= 0; i < item_in->left_expr->cols(); i++) + { + Item_func_eq *eq_cond; /* New equi-join condition for the current column. */ + /* Item for the corresponding field from the materialized temp table. */ + Item_field *right_col_item; + + if (!(right_col_item= new Item_field(thd, context, tmp_table->field[i])) || + !(eq_cond= new Item_func_eq(item_in->left_expr->element_index(i), + right_col_item)) || + (((Item_cond_and*)semi_join_conds)->add(eq_cond))) + { + delete semi_join_conds; + semi_join_conds= NULL; + DBUG_RETURN(TRUE); + } + } + if (semi_join_conds->fix_fields(thd, (Item**)&semi_join_conds)) + DBUG_RETURN(TRUE); + + DBUG_RETURN(FALSE); +} + + +/** + Create a new uniquesubquery engine for the execution of an IN predicate. + + @details + Create and initialize a new JOIN_TAB, and Table_ref objects to perform + lookups into the indexed temporary table. + + @retval A new subselect_hash_sj_engine object + @retval NULL if a memory allocation error occurs +*/ + +subselect_uniquesubquery_engine* +subselect_hash_sj_engine::make_unique_engine() +{ + Item_in_subselect *item_in= (Item_in_subselect *) item; + /* The only index on the temporary table. */ + KEY *tmp_key= tmp_table->key_info; + /* Number of keyparts in tmp_key. */ + uint tmp_key_parts= tmp_key->key_parts; + JOIN_TAB *tab; + + DBUG_ENTER("subselect_hash_sj_engine::make_unique_engine"); /* Create and initialize the JOIN_TAB that represents an index lookup @@ -3328,9 +3837,9 @@ - this JOIN_TAB has no corresponding JOIN (and doesn't need one), and - here we initialize only those members that are used by subselect_uniquesubquery_engine, so these objects are incomplete. - */ + */ if (!(tab= (JOIN_TAB*) thd->alloc(sizeof(JOIN_TAB)))) - DBUG_RETURN(TRUE); + DBUG_RETURN(NULL); tab->table= tmp_table; tab->ref.key= 0; /* The only temp table index. */ tab->ref.key_length= tmp_key->key_length; @@ -3341,60 +3850,18 @@ (tmp_key_parts + 1)))) || !(tab->ref.items= (Item**) thd->alloc(sizeof(Item*) * tmp_key_parts))) - DBUG_RETURN(TRUE); + DBUG_RETURN(NULL); KEY_PART_INFO *cur_key_part= tmp_key->key_part; store_key **ref_key= tab->ref.key_copy; uchar *cur_ref_buff= tab->ref.key_buff; - - /* - Create an artificial condition to post-filter those rows matched by index - lookups that cannot be distinguished by the index lookup procedure, e.g. - because of truncation. Prepared statements execution requires that - fix_fields is called for every execution. In order to call fix_fields we - need to create a Name_resolution_context and a corresponding TABLE_LIST - for the temporary table for the subquery, so that all column references - to the materialized subquery table can be resolved correctly. - */ - DBUG_ASSERT(cond == NULL); - if (!(cond= new Item_cond_and)) - DBUG_RETURN(TRUE); - /* - Table reference for tmp_table that is used to resolve column references - (Item_fields) to columns in tmp_table. - */ - TABLE_LIST *tmp_table_ref; - if (!(tmp_table_ref= (TABLE_LIST*) thd->alloc(sizeof(TABLE_LIST)))) - DBUG_RETURN(TRUE); - - tmp_table_ref->init_one_table("", "materialized subselect", TL_READ); - tmp_table_ref->table= tmp_table; - - /* Name resolution context for all tmp_table columns created below. */ - Name_resolution_context *context= new Name_resolution_context; - context->init(); - context->first_name_resolution_table= - context->last_name_resolution_table= tmp_table_ref; for (uint i= 0; i < tmp_key_parts; i++, cur_key_part++, ref_key++) { - Item_func_eq *eq_cond; /* New equi-join condition for the current column. */ - /* Item for the corresponding field from the materialized temp table. */ - Item_field *right_col_item; + tab->ref.items[i]= item_in->left_expr->element_index(i); int null_count= test(cur_key_part->field->real_maybe_null()); - tab->ref.items[i]= item_in->left_expr->element_index(i); - - if (!(right_col_item= new Item_field(thd, context, cur_key_part->field)) || - !(eq_cond= new Item_func_eq(tab->ref.items[i], right_col_item)) || - ((Item_cond_and*)cond)->add(eq_cond)) - { - delete cond; - cond= NULL; - DBUG_RETURN(TRUE); - } - *ref_key= new store_key_item(thd, cur_key_part->field, - /* TODO: + /* TIMOUR: the NULL byte is taken into account in cur_key_part->store_length, so instead of cur_ref_buff + test(maybe_null), we could @@ -3409,10 +3876,8 @@ tab->ref.key_err= 1; tab->ref.key_parts= tmp_key_parts; - if (cond->fix_fields(thd, &cond)) - DBUG_RETURN(TRUE); - - DBUG_RETURN(FALSE); + DBUG_RETURN(new subselect_uniquesubquery_engine(thd, tab, item, + semi_join_conds)); } @@ -3435,7 +3900,8 @@ Repeat name resolution for 'cond' since cond is not part of any clause of the query, and it is not 'fixed' during JOIN::prepare. */ - if (cond && !cond->fixed && cond->fix_fields(thd, &cond)) + if (semi_join_conds && !semi_join_conds->fixed && + semi_join_conds->fix_fields(thd, (Item**)&semi_join_conds)) return TRUE; /* Let our engine reuse this query plan for materialization. */ materialize_join= materialize_engine->join; @@ -3446,32 +3912,53 @@ subselect_hash_sj_engine::~subselect_hash_sj_engine() { + delete lookup_engine; delete result; - if (tab) - free_tmp_table(thd, tab->table); + if (tmp_table) + free_tmp_table(thd, tmp_table); } /** Cleanup performed after each PS execution. - @detail + @details Called in the end of JOIN::prepare for PS from Item_subselect::cleanup. */ void subselect_hash_sj_engine::cleanup() { + enum_engine_type lookup_engine_type= lookup_engine->engine_type(); is_materialized= FALSE; + bitmap_clear_all(&non_null_key_parts); + bitmap_clear_all(&partial_match_key_parts); + count_partial_match_columns= 0; + count_null_only_columns= 0; + strategy= UNDEFINED; + materialize_engine->cleanup(); + if (lookup_engine_type == TABLE_SCAN_ENGINE || + lookup_engine_type == ROWID_MERGE_ENGINE) + { + subselect_engine *inner_lookup_engine; + inner_lookup_engine= + ((subselect_partial_match_engine*) lookup_engine)->lookup_engine; + /* + Partial match engines are recreated for each PS execution inside + subselect_hash_sj_engine::exec(). + */ + delete lookup_engine; + lookup_engine= inner_lookup_engine; + } + DBUG_ASSERT(lookup_engine->engine_type() == UNIQUESUBQUERY_ENGINE); + lookup_engine->cleanup(); result->cleanup(); /* Resets the temp table as well. */ - materialize_engine->cleanup(); - subselect_uniquesubquery_engine::cleanup(); } /** Execute a subquery IN predicate via materialization. - @detail + @details If needed materialize the subquery into a temporary table, then copmpute the predicate via a lookup into this table. @@ -3482,6 +3969,9 @@ int subselect_hash_sj_engine::exec() { Item_in_subselect *item_in= (Item_in_subselect *) item; + SELECT_LEX *save_select= thd->lex->current_select; + subselect_partial_match_engine *pm_engine= NULL; + int res= 0; DBUG_ENTER("subselect_hash_sj_engine::exec"); @@ -3489,56 +3979,126 @@ Optimize and materialize the subquery during the first execution of the subquery predicate. */ - if (!is_materialized) - { - int res= 0; - SELECT_LEX *save_select= thd->lex->current_select; - thd->lex->current_select= materialize_engine->select_lex; - if ((res= materialize_join->optimize())) - goto err; /* purecov: inspected */ - materialize_join->exec(); - if ((res= test(materialize_join->error || thd->is_fatal_error))) - goto err; - - /* - TODO: - - Unlock all subquery tables as we don't need them. To implement this - we need to add new functionality to JOIN::join_free that can unlock - all tables in a subquery (and all its subqueries). - - The temp table used for grouping in the subquery can be freed - immediately after materialization (yet it's done together with - unlocking). - */ - is_materialized= TRUE; - /* - If the subquery returned no rows, the temporary table is empty, so we know - directly that the result of IN is FALSE. We first update the table - statistics, then we test if the temporary table for the query result is - empty. - */ - tab->table->file->info(HA_STATUS_VARIABLE); - if (!tab->table->file->stats.records) - { - empty_result_set= TRUE; - item_in->value= FALSE; - /* TODO: check we need this: item_in->null_value= FALSE; */ - DBUG_RETURN(FALSE); - } - /* Set tmp_param only if its usable, i.e. tmp_param->copy_field != NULL. */ - tmp_param= &(item_in->unit->outer_select()->join->tmp_table_param); - if (tmp_param && !tmp_param->copy_field) - tmp_param= NULL; + thd->lex->current_select= materialize_engine->select_lex; + if ((res= materialize_join->optimize())) + goto err; /* purecov: inspected */ + DBUG_ASSERT(!is_materialized); /* We should materialize only once. */ + materialize_join->exec(); + if ((res= test(materialize_join->error || thd->is_fatal_error))) + goto err; + + /* + TODO: + - Unlock all subquery tables as we don't need them. To implement this + we need to add new functionality to JOIN::join_free that can unlock + all tables in a subquery (and all its subqueries). + - The temp table used for grouping in the subquery can be freed + immediately after materialization (yet it's done together with + unlocking). + */ + is_materialized= TRUE; + /* + If the subquery returned no rows, the temporary table is empty, so we know + directly that the result of IN is FALSE. We first update the table + statistics, then we test if the temporary table for the query result is + empty. + */ + tmp_table->file->info(HA_STATUS_VARIABLE); + if (!tmp_table->file->stats.records) + { + item_in->value= FALSE; + /* The value of IN will not change during this execution. */ + item_in->is_constant= TRUE; + item_in->set_first_execution(); + /* TIMOUR: check if we need this: item_in->null_value= FALSE; */ + DBUG_RETURN(FALSE); + } + + /* + TIMOUR: The schema-based analysis for partial matching can be done once for + prepared statement and remembered. It is done here to remove the need to + save/restore all related variables between each re-execution, thus making + the code simpler. + */ + strategy= get_strategy_using_schema(); + /* This call may discover that we don't need partial matching at all. */ + strategy= get_strategy_using_data(); + if (strategy == PARTIAL_MATCH) + { + uint count_pm_keys; /* Total number of keys needed for partial matching. */ + MY_BITMAP *nn_key_parts; /* The key parts of the only non-NULL index. */ + uint covering_null_row_width; + select_materialize_with_stats *result_sink= + (select_materialize_with_stats *) result; + + nn_key_parts= (count_partial_match_columns < tmp_table->s->fields) ? + &non_null_key_parts : NULL; + + if (result_sink->get_max_nulls_in_row() == + tmp_table->s->fields - + (nn_key_parts ? bitmap_bits_set(nn_key_parts) : 0)) + covering_null_row_width= result_sink->get_max_nulls_in_row(); + else + covering_null_row_width= 0; + + if (covering_null_row_width) + count_pm_keys= nn_key_parts ? 1 : 0; + else + count_pm_keys= count_partial_match_columns - count_null_only_columns + + (nn_key_parts ? 1 : 0); + + choose_partial_match_strategy(test(nn_key_parts), + test(covering_null_row_width), + &partial_match_key_parts); + DBUG_ASSERT(strategy == PARTIAL_MATCH_MERGE || + strategy == PARTIAL_MATCH_SCAN); + if (strategy == PARTIAL_MATCH_MERGE) + { + pm_engine= + new subselect_rowid_merge_engine((subselect_uniquesubquery_engine*) + lookup_engine, tmp_table, + count_pm_keys, + covering_null_row_width, + item, result, + semi_join_conds->argument_list()); + if (!pm_engine || + ((subselect_rowid_merge_engine*) pm_engine)-> + init(nn_key_parts, &partial_match_key_parts)) + { + /* + The call to init() would fail if there was not enough memory to allocate + all buffers for the rowid merge strategy. In this case revert to table + scanning which doesn't need any big buffers. + */ + delete pm_engine; + pm_engine= NULL; + strategy= PARTIAL_MATCH_SCAN; + } + } + + if (strategy == PARTIAL_MATCH_SCAN) + { + if (!(pm_engine= + new subselect_table_scan_engine((subselect_uniquesubquery_engine*) + lookup_engine, tmp_table, + item, result, + semi_join_conds->argument_list(), + covering_null_row_width))) + { + /* This is an irrecoverable error. */ + res= 1; + goto err; + } + } + } + + if (pm_engine) + lookup_engine= pm_engine; + item_in->change_engine(lookup_engine); err: - thd->lex->current_select= save_select; - if (res) - DBUG_RETURN(res); - } - - /* - Lookup the left IN operand in the hash index of the materialized subquery. - */ - DBUG_RETURN(subselect_uniquesubquery_engine::exec()); + thd->lex->current_select= save_select; + DBUG_RETURN(res); } @@ -3551,10 +4111,1008 @@ str->append(STRING_WITH_LEN(" <materialize> (")); materialize_engine->print(str, query_type); str->append(STRING_WITH_LEN(" ), ")); - if (tab) - subselect_uniquesubquery_engine::print(str, query_type); + + if (lookup_engine) + lookup_engine->print(str, query_type); else str->append(STRING_WITH_LEN( - "<the access method for lookups is not yet created>" + "<engine selected at execution time>" )); } + +void subselect_hash_sj_engine::fix_length_and_dec(Item_cache** row) +{ + DBUG_ASSERT(FALSE); +} + +void subselect_hash_sj_engine::exclude() +{ + DBUG_ASSERT(FALSE); +} + +bool subselect_hash_sj_engine::no_tables() +{ + DBUG_ASSERT(FALSE); + return FALSE; +} + +bool subselect_hash_sj_engine::change_result(Item_subselect *si, + select_result_interceptor *res) +{ + DBUG_ASSERT(FALSE); + return TRUE; +} + + +Ordered_key::Ordered_key(uint keyid_arg, TABLE *tbl_arg, Item *search_key_arg, + ha_rows null_count_arg, ha_rows min_null_row_arg, + ha_rows max_null_row_arg, uchar *row_num_to_rowid_arg) + : keyid(keyid_arg), tbl(tbl_arg), search_key(search_key_arg), + row_num_to_rowid(row_num_to_rowid_arg), null_count(null_count_arg) +{ + DBUG_ASSERT(tbl->file->stats.records > null_count); + key_buff_elements= tbl->file->stats.records - null_count; + cur_key_idx= HA_POS_ERROR; + + DBUG_ASSERT((null_count && min_null_row_arg && max_null_row_arg) || + (!null_count && !min_null_row_arg && !max_null_row_arg)); + if (null_count) + { + /* The counters are 1-based, for key access we need 0-based indexes. */ + min_null_row= min_null_row_arg - 1; + max_null_row= max_null_row_arg - 1; + } + else + min_null_row= max_null_row= 0; +} + + +Ordered_key::~Ordered_key() +{ + my_free((char*) key_buff, MYF(0)); + bitmap_free(&null_key); +} + + +/* + Cleanup that needs to be done for each PS (re)execution. +*/ + +void Ordered_key::cleanup() +{ + /* + Currently these keys are recreated for each PS re-execution, thus + there is nothing to cleanup, the whole object goes away after execution + is over. All handler related initialization/deinitialization is done by + the parent subselect_rowid_merge_engine object. + */ +} + + +/* + Initialize a multi-column index. +*/ + +bool Ordered_key::init(MY_BITMAP *columns_to_index) +{ + THD *thd= tbl->in_use; + uint cur_key_col= 0; + Item_field *cur_tmp_field; + Item_func_lt *fn_less_than; + + key_column_count= bitmap_bits_set(columns_to_index); + + // TIMOUR: check for mem allocation err, revert to scan + + key_columns= (Item_field**) thd->alloc(key_column_count * + sizeof(Item_field*)); + compare_pred= (Item_func_lt**) thd->alloc(key_column_count * + sizeof(Item_func_lt*)); + + for (uint i= 0; i < columns_to_index->n_bits; i++) + { + if (!bitmap_is_set(columns_to_index, i)) + continue; + cur_tmp_field= new Item_field(tbl->field[i]); + /* Create the predicate (tmp_column[i] < outer_ref[i]). */ + fn_less_than= new Item_func_lt(cur_tmp_field, + search_key->element_index(i)); + fn_less_than->fix_fields(thd, (Item**) &fn_less_than); + key_columns[cur_key_col]= cur_tmp_field; + compare_pred[cur_key_col]= fn_less_than; + ++cur_key_col; + } + + if (alloc_keys_buffers()) + { + /* TIMOUR revert to partial match via table scan. */ + return TRUE; + } + return FALSE; +} + + +/* + Initialize a single-column index. +*/ + +bool Ordered_key::init(int col_idx) +{ + THD *thd= tbl->in_use; + + key_column_count= 1; + + // TIMOUR: check for mem allocation err, revert to scan + + key_columns= (Item_field**) thd->alloc(sizeof(Item_field*)); + compare_pred= (Item_func_lt**) thd->alloc(sizeof(Item_func_lt*)); + + key_columns[0]= new Item_field(tbl->field[col_idx]); + /* Create the predicate (tmp_column[i] < outer_ref[i]). */ + compare_pred[0]= new Item_func_lt(key_columns[0], + search_key->element_index(col_idx)); + compare_pred[0]->fix_fields(thd, (Item**)&compare_pred[0]); + + if (alloc_keys_buffers()) + { + /* TIMOUR revert to partial match via table scan. */ + return TRUE; + } + return FALSE; +} + + +/* + Allocate the buffers for both the row number, and the NULL-bitmap indexes. +*/ + +bool Ordered_key::alloc_keys_buffers() +{ + DBUG_ASSERT(key_buff_elements > 0); + + if (!(key_buff= (rownum_t*) my_malloc(key_buff_elements * sizeof(rownum_t), + MYF(MY_WME)))) + return TRUE; + + /* + TIMOUR: it is enough to create bitmaps with size + (max_null_row - min_null_row), and then use min_null_row as + lookup offset. + */ + /* Notice that max_null_row is max array index, we need count, so +1. */ + if (bitmap_init(&null_key, NULL, max_null_row + 1, FALSE)) + return TRUE; + + cur_key_idx= HA_POS_ERROR; + + return FALSE; +} + + +/* + Quick sort comparison function that compares two rows of the same table + indentfied with their row numbers. + + @retval -1 + @retval 0 + @retval +1 +*/ + +int +Ordered_key::cmp_keys_by_row_data(ha_rows a, ha_rows b) +{ + uchar *rowid_a, *rowid_b; + int error, cmp_res; + /* The length in bytes of the rowids (positions) of tmp_table. */ + uint rowid_length= tbl->file->ref_length; + + if (a == b) + return 0; + /* Get the corresponding rowids. */ + rowid_a= row_num_to_rowid + a * rowid_length; + rowid_b= row_num_to_rowid + b * rowid_length; + /* Fetch the rows for comparison. */ + error= tbl->file->ha_rnd_pos(tbl->record[0], rowid_a); + DBUG_ASSERT(!error); + error= tbl->file->ha_rnd_pos(tbl->record[1], rowid_b); + DBUG_ASSERT(!error); + /* + Compare the two rows by the corresponding values of the indexed + columns. + */ + for (uint i= 0; i < key_column_count; i++) + { + Field *cur_field= key_columns[i]->field; + if ((cmp_res= cur_field->cmp_offset(tbl->s->rec_buff_length))) + return (cmp_res > 0 ? 1 : -1); + } + return 0; +} + + +int +Ordered_key::cmp_keys_by_row_data_and_rownum(Ordered_key *key, + rownum_t* a, rownum_t* b) +{ + /* The result of comparing the two keys according to their row data. */ + int cmp_row_res= key->cmp_keys_by_row_data(*a, *b); + if (cmp_row_res) + return cmp_row_res; + return (*a < *b) ? -1 : (*a > *b) ? 1 : 0; +} + + +void Ordered_key::sort_keys() +{ + my_qsort2(key_buff, key_buff_elements, sizeof(rownum_t), + (qsort2_cmp) &cmp_keys_by_row_data_and_rownum, (void*) this); + /* Invalidate the current row position. */ + cur_key_idx= HA_POS_ERROR; +} + + +/* + The fraction of rows that do not contain NULL in the columns indexed by + this key. + + @retval 1 if there are no NULLs + @retval 0 if only NULLs +*/ + +double Ordered_key::null_selectivity() +{ + /* We should not be processing empty tables. */ + DBUG_ASSERT(tbl->file->stats.records); + return (1 - (double) null_count / (double) tbl->file->stats.records); +} + + +/* + Compare the value(s) of the current key in 'search_key' with the + data of the current table record. + + @notes The comparison result follows from the way compare_pred + is created in Ordered_key::init. Currently compare_pred compares + a field in of the current row with the corresponding Item that + contains the search key. + + @param row_num Number of the row (not index in the key_buff array) + + @retval -1 if (current row < search_key) + @retval 0 if (current row == search_key) + @retval +1 if (current row > search_key) +*/ + +int Ordered_key::cmp_key_with_search_key(rownum_t row_num) +{ + /* The length in bytes of the rowids (positions) of tmp_table. */ + uint rowid_length= tbl->file->ref_length; + uchar *cur_rowid= row_num_to_rowid + row_num * rowid_length; + int error, cmp_res; + + error= tbl->file->ha_rnd_pos(tbl->record[0], cur_rowid); + DBUG_ASSERT(!error); + + for (uint i= 0; i < key_column_count; i++) + { + cmp_res= compare_pred[i]->get_comparator()->compare(); + /* Unlike Arg_comparator::compare_row() here there should be no NULLs. */ + DBUG_ASSERT(!compare_pred[i]->null_value); + if (cmp_res) + return (cmp_res > 0 ? 1 : -1); + } + return 0; +} + + +/* + Find a key in a sorted array of keys via binary search. + + see create_subq_in_equalities() +*/ + +bool Ordered_key::lookup() +{ + DBUG_ASSERT(key_buff_elements); + + ha_rows lo= 0; + ha_rows hi= key_buff_elements - 1; + ha_rows mid; + int cmp_res; + + while (lo <= hi) + { + mid= lo + (hi - lo) / 2; + cmp_res= cmp_key_with_search_key(key_buff[mid]); + /* + In order to find the minimum match, check if the pevious element is + equal or smaller than the found one. If equal, we need to search further + to the left. + */ + if (!cmp_res && mid > 0) + cmp_res= !cmp_key_with_search_key(key_buff[mid - 1]) ? 1 : 0; + + if (cmp_res == -1) + { + /* row[mid] < search_key */ + lo= mid + 1; + } + else if (cmp_res == 1) + { + /* row[mid] > search_key */ + if (!mid) + goto not_found; + hi= mid - 1; + } + else + { + /* row[mid] == search_key */ + cur_key_idx= mid; + return TRUE; + } + } +not_found: + cur_key_idx= HA_POS_ERROR; + return FALSE; +} + + +/* + Move the current index pointer to the next key with the same column + values as the current key. Since the index is sorted, all such keys + are contiguous. +*/ + +bool Ordered_key::next_same() +{ + DBUG_ASSERT(key_buff_elements); + + if (cur_key_idx < key_buff_elements - 1) + { + /* + TIMOUR: + The below is quite inefficient, since as a result we will fetch every + row (except the last one) twice. There must be a more efficient way, + e.g. swapping record[0] and record[1], and reading only the new record. + */ + if (!cmp_keys_by_row_data(key_buff[cur_key_idx], key_buff[cur_key_idx + 1])) + { + ++cur_key_idx; + return TRUE; + } + } + return FALSE; +} + + +void Ordered_key::print(String *str) +{ + uint i; + str->append("{idx="); + str->qs_append(keyid); + str->append(", ("); + for (i= 0; i < key_column_count - 1; i++) + { + str->append(key_columns[i]->field->field_name); + str->append(", "); + } + str->append(key_columns[i]->field->field_name); + str->append("), "); + + str->append("null_bitmap: (bits="); + str->qs_append(null_key.n_bits); + str->append(", nulls= "); + str->qs_append((double)null_count); + str->append(", min_null= "); + str->qs_append((double)min_null_row); + str->append(", max_null= "); + str->qs_append((double)max_null_row); + str->append("), "); + + str->append('}'); +} + + +subselect_partial_match_engine::subselect_partial_match_engine( + subselect_uniquesubquery_engine *engine_arg, + TABLE *tmp_table_arg, Item_subselect *item_arg, + select_result_interceptor *result_arg, + List<Item> *equi_join_conds_arg, + uint covering_null_row_width_arg) + :subselect_engine(item_arg, result_arg), + tmp_table(tmp_table_arg), lookup_engine(engine_arg), + equi_join_conds(equi_join_conds_arg), + covering_null_row_width(covering_null_row_width_arg) +{} + + +int subselect_partial_match_engine::exec() +{ + Item_in_subselect *item_in= (Item_in_subselect *) item; + int res; + + /* Try to find a matching row by index lookup. */ + res= lookup_engine->copy_ref_key_simple(); + if (res == -1) + { + /* The result is FALSE based on the outer reference. */ + item_in->value= 0; + item_in->null_value= 0; + return 0; + } + else if (res == 0) + { + /* Search for a complete match. */ + if ((res= lookup_engine->index_lookup())) + { + /* An error occured during lookup(). */ + item_in->value= 0; + item_in->null_value= 0; + return res; + } + else if (item_in->value) + { + /* + A complete match was found, the result of IN is TRUE. + Notice: (this->item == lookup_engine->item) + */ + return 0; + } + } + + if (covering_null_row_width == tmp_table->s->fields) + { + /* + If there is a NULL-only row that coveres all columns the result of IN + is UNKNOWN. + */ + item_in->value= 0; + /* + TIMOUR: which one is the right way to propagate an UNKNOWN result? + Should we also set empty_result_set= FALSE; ??? + */ + //item_in->was_null= 1; + item_in->null_value= 1; + return 0; + } + + /* + There is no complete match. Look for a partial match (UNKNOWN result), or + no match (FALSE). + */ + if (tmp_table->file->inited) + tmp_table->file->ha_index_end(); + + if (partial_match()) + { + /* The result of IN is UNKNOWN. */ + item_in->value= 0; + /* + TIMOUR: which one is the right way to propagate an UNKNOWN result? + Should we also set empty_result_set= FALSE; ??? + */ + //item_in->was_null= 1; + item_in->null_value= 1; + } + else + { + /* The result of IN is FALSE. */ + item_in->value= 0; + /* + TIMOUR: which one is the right way to propagate an UNKNOWN result? + Should we also set empty_result_set= FALSE; ??? + */ + //item_in->was_null= 0; + item_in->null_value= 0; + } + + return 0; +} + + +void subselect_partial_match_engine::print(String *str, + enum_query_type query_type) +{ + /* + Should never be called as the actual engine cannot be known at query + optimization time. + */ + DBUG_ASSERT(FALSE); +} + + +/* + @param non_null_key_parts + @param partial_match_key_parts A union of all single-column NULL key parts. + @param count_partial_match_columns Number of NULL keyparts (set bits above). + + @retval FALSE the engine was initialized successfully + @retval TRUE there was some (memory allocation) error during initialization, + such errors should be interpreted as revert to other strategy +*/ + +bool +subselect_rowid_merge_engine::init(MY_BITMAP *non_null_key_parts, + MY_BITMAP *partial_match_key_parts) +{ + /* The length in bytes of the rowids (positions) of tmp_table. */ + uint rowid_length= tmp_table->file->ref_length; + ha_rows row_count= tmp_table->file->stats.records; + rownum_t cur_rownum= 0; + select_materialize_with_stats *result_sink= + (select_materialize_with_stats *) result; + uint cur_keyid= 0; + Item_in_subselect *item_in= (Item_in_subselect*) item; + int error; + + if (keys_count == 0) + { + /* There is nothing to initialize, we will only do regular lookups. */ + return FALSE; + } + + DBUG_ASSERT(!covering_null_row_width || (covering_null_row_width && + keys_count == 1 && + non_null_key_parts)); + /* + Allocate buffers to hold the merged keys and the mapping between rowids and + row numbers. + */ + if (!(merge_keys= (Ordered_key**) thd->alloc(keys_count * + sizeof(Ordered_key*))) || + !(row_num_to_rowid= (uchar*) my_malloc(row_count * rowid_length * + sizeof(uchar), MYF(MY_WME)))) + return TRUE; + + /* Create the only non-NULL key if there is any. */ + if (non_null_key_parts) + { + non_null_key= new Ordered_key(cur_keyid, tmp_table, item_in->left_expr, + 0, 0, 0, row_num_to_rowid); + if (non_null_key->init(non_null_key_parts)) + return TRUE; + merge_keys[cur_keyid]= non_null_key; + merge_keys[cur_keyid]->first(); + ++cur_keyid; + } + + /* + If there is a covering NULL row, the only key that is needed is the + only non-NULL key that is already created above. We create keys on + NULL-able columns only if there is no covering NULL row. + */ + if (!covering_null_row_width) + { + if (bitmap_init_memroot(&matching_keys, keys_count, thd->mem_root) || + bitmap_init_memroot(&matching_outer_cols, keys_count, thd->mem_root) || + bitmap_init_memroot(&null_only_columns, keys_count, thd->mem_root)) + return TRUE; + + /* + Create one single-column NULL-key for each column in + partial_match_key_parts. + */ + for (uint i= 0; i < partial_match_key_parts->n_bits; i++) + { + if (!bitmap_is_set(partial_match_key_parts, i)) + continue; + + if (result_sink->get_null_count_of_col(i) == row_count) + bitmap_set_bit(&null_only_columns, cur_keyid); + else + { + merge_keys[cur_keyid]= new Ordered_key( + cur_keyid, tmp_table, + item_in->left_expr->element_index(i), + result_sink->get_null_count_of_col(i), + result_sink->get_min_null_of_col(i), + result_sink->get_max_null_of_col(i), + row_num_to_rowid); + if (merge_keys[cur_keyid]->init(i)) + return TRUE; + merge_keys[cur_keyid]->first(); + } + ++cur_keyid; + } + } + + /* Populate the indexes with data from the temporary table. */ + tmp_table->file->ha_rnd_init(1); + tmp_table->file->extra_opt(HA_EXTRA_CACHE, + current_thd->variables.read_buff_size); + tmp_table->null_row= 0; + while (TRUE) + { + error= tmp_table->file->ha_rnd_next(tmp_table->record[0]); + if (error == HA_ERR_RECORD_DELETED) + { + /* We get this for duplicate records that should not be in tmp_table. */ + continue; + } + /* + This is a temp table that we fully own, there should be no other + cause to stop the iteration than EOF. + */ + DBUG_ASSERT(!error || error == HA_ERR_END_OF_FILE); + if (error == HA_ERR_END_OF_FILE) + { + DBUG_ASSERT(cur_rownum == tmp_table->file->stats.records); + break; + } + + /* + Save the position of this record in the row_num -> rowid mapping. + */ + tmp_table->file->position(tmp_table->record[0]); + memcpy(row_num_to_rowid + cur_rownum * rowid_length, + tmp_table->file->ref, rowid_length); + + /* Add the current row number to the corresponding keys. */ + if (non_null_key) + { + /* By definition there are no NULLs in the non-NULL key. */ + non_null_key->add_key(cur_rownum); + } + + for (uint i= (non_null_key ? 1 : 0); i < keys_count; i++) + { + /* + Check if the first and only indexed column contains NULL in the curent + row, and add the row number to the corresponding key. + */ + if (tmp_table->field[merge_keys[i]->get_field_idx(0)]->is_null()) + merge_keys[i]->set_null(cur_rownum); + else + merge_keys[i]->add_key(cur_rownum); + } + ++cur_rownum; + } + + tmp_table->file->ha_rnd_end(); + + /* Sort all the keys by their NULL selectivity. */ + my_qsort(merge_keys, keys_count, sizeof(Ordered_key*), + (qsort_cmp) cmp_keys_by_null_selectivity); + + /* Sort the keys in each of the indexes. */ + for (uint i= 0; i < keys_count; i++) + merge_keys[i]->sort_keys(); + + if (init_queue(&pq, keys_count, 0, FALSE, + subselect_rowid_merge_engine::cmp_keys_by_cur_rownum, NULL)) + return TRUE; + + return FALSE; +} + + +subselect_rowid_merge_engine::~subselect_rowid_merge_engine() +{ + /* None of the resources below is allocated if there are no ordered keys. */ + if (keys_count) + { + my_free((char*) row_num_to_rowid, MYF(0)); + for (uint i= 0; i < keys_count; i++) + delete merge_keys[i]; + delete_queue(&pq); + if (tmp_table->file->inited == handler::RND) + tmp_table->file->ha_rnd_end(); + } +} + + +void subselect_rowid_merge_engine::cleanup() +{ +} + + +/* + Quick sort comparison function to compare keys in order of decreasing bitmap + selectivity, so that the most selective keys come first. + + @param k1 first key to compare + @param k2 second key to compare + + @retval 1 if k1 is less selective than k2 + @retval 0 if k1 is equally selective as k2 + @retval -1 if k1 is more selective than k2 +*/ + +int +subselect_rowid_merge_engine::cmp_keys_by_null_selectivity(Ordered_key **k1, + Ordered_key **k2) +{ + double k1_sel= (*k1)->null_selectivity(); + double k2_sel= (*k2)->null_selectivity(); + if (k1_sel < k2_sel) + return 1; + if (k1_sel > k2_sel) + return -1; + return 0; +} + + +/* +*/ + +int +subselect_rowid_merge_engine::cmp_keys_by_cur_rownum(void *arg, + uchar *k1, uchar *k2) +{ + rownum_t r1= ((Ordered_key*) k1)->current(); + rownum_t r2= ((Ordered_key*) k2)->current(); + + return (r1 < r2) ? -1 : (r1 > r2) ? 1 : 0; +} + + +/* + Check if certain table row contains a NULL in all columns for which there is + no match in the corresponding value index. + + @retval TRUE if a NULL row exists + @retval FALSE otherwise +*/ + +bool subselect_rowid_merge_engine::test_null_row(rownum_t row_num) +{ + Ordered_key *cur_key; + uint cur_id; + for (uint i = 0; i < keys_count; i++) + { + cur_key= merge_keys[i]; + cur_id= cur_key->get_keyid(); + if (bitmap_is_set(&matching_keys, cur_id)) + { + /* + The key 'i' (with id 'cur_keyid') already matches a value in row 'row_num', + thus we skip it as it can't possibly match a NULL. + */ + continue; + } + if (!cur_key->is_null(row_num)) + return FALSE; + } + return TRUE; +} + + +/* + @retval TRUE there is a partial match (UNKNOWN) + @retval FALSE there is no match at all (FALSE) +*/ + +bool subselect_rowid_merge_engine::partial_match() +{ + Ordered_key *min_key; /* Key that contains the current minimum position. */ + rownum_t min_row_num; /* Current row number of min_key. */ + Ordered_key *cur_key; + rownum_t cur_row_num; + uint count_nulls_in_search_key= 0; + bool res= FALSE; + + /* If there is a non-NULL key, it must be the first key in the keys array. */ + DBUG_ASSERT(!non_null_key || (non_null_key && merge_keys[0] == non_null_key)); + + /* All data accesses during execution are via handler::ha_rnd_pos() */ + tmp_table->file->ha_rnd_init(0); + + /* Check if there is a match for the columns of the only non-NULL key. */ + if (non_null_key && !non_null_key->lookup()) + { + res= FALSE; + goto end; + } + + /* + If there is a NULL (sub)row that covers all NULL-able columns, + then there is a guranteed partial match, and we don't need to search + for the matching row. + */ + if (covering_null_row_width) + { + res= TRUE; + goto end; + } + + if (non_null_key) + queue_insert(&pq, (uchar *) non_null_key); + /* + Do not add the non_null_key, since it was already processed above. + */ + bitmap_clear_all(&matching_outer_cols); + for (uint i= test(non_null_key); i < keys_count; i++) + { + DBUG_ASSERT(merge_keys[i]->get_column_count() == 1); + if (merge_keys[i]->get_search_key(0)->is_null()) + { + ++count_nulls_in_search_key; + bitmap_set_bit(&matching_outer_cols, merge_keys[i]->get_keyid()); + } + else if (merge_keys[i]->lookup()) + queue_insert(&pq, (uchar *) merge_keys[i]); + } + + /* + If the outer reference consists of only NULLs, or if it has NULLs in all + nullable columns, the result is UNKNOWN. + */ + if (count_nulls_in_search_key == + ((Item_in_subselect *) item)->left_expr->cols() - + (non_null_key ? non_null_key->get_column_count() : 0)) + { + res= TRUE; + goto end; + } + + /* + If there is no NULL (sub)row that covers all NULL columns, and there is no + single match for any of the NULL columns, the result is FALSE. + */ + if (pq.elements - test(non_null_key) == 0) + { + res= FALSE; + goto end; + } + + DBUG_ASSERT(pq.elements); + + min_key= (Ordered_key*) queue_remove(&pq, 0); + min_row_num= min_key->current(); + bitmap_copy(&matching_keys, &null_only_columns); + bitmap_set_bit(&matching_keys, min_key->get_keyid()); + bitmap_union(&matching_keys, &matching_outer_cols); + if (min_key->next_same()) + queue_insert(&pq, (uchar *) min_key); + + if (pq.elements == 0) + { + /* + Check the only matching row of the only key min_key for NULL matches + in the other columns. + */ + res= test_null_row(min_row_num); + goto end; + } + + while (TRUE) + { + cur_key= (Ordered_key*) queue_remove(&pq, 0); + cur_row_num= cur_key->current(); + + if (cur_row_num == min_row_num) + bitmap_set_bit(&matching_keys, cur_key->get_keyid()); + else + { + /* Follows from the correct use of priority queue. */ + DBUG_ASSERT(cur_row_num > min_row_num); + if (test_null_row(min_row_num)) + { + res= TRUE; + goto end; + } + else + { + min_key= cur_key; + min_row_num= cur_row_num; + bitmap_copy(&matching_keys, &null_only_columns); + bitmap_set_bit(&matching_keys, min_key->get_keyid()); + bitmap_union(&matching_keys, &matching_outer_cols); + } + } + + if (cur_key->next_same()) + queue_insert(&pq, (uchar *) cur_key); + + if (pq.elements == 0) + { + /* Check the last row of the last column in PQ for NULL matches. */ + res= test_null_row(min_row_num); + goto end; + } + } + + /* We should never get here - all branches must be handled explicitly above. */ + DBUG_ASSERT(FALSE); + +end: + tmp_table->file->ha_rnd_end(); + return res; +} + + +subselect_table_scan_engine::subselect_table_scan_engine( + subselect_uniquesubquery_engine *engine_arg, + TABLE *tmp_table_arg, + Item_subselect *item_arg, + select_result_interceptor *result_arg, + List<Item> *equi_join_conds_arg, + uint covering_null_row_width_arg) + :subselect_partial_match_engine(engine_arg, tmp_table_arg, item_arg, + result_arg, equi_join_conds_arg, + covering_null_row_width_arg) +{} + + +/* + TIMOUR: + This method is based on subselect_uniquesubquery_engine::scan_table(). + Consider refactoring somehow, 80% of the code is the same. + + for each row_i in tmp_table + { + count_matches= 0; + for each row element row_i[j] + { + if (outer_ref[j] is NULL || row_i[j] is NULL || outer_ref[j] == row_i[j]) + ++count_matches; + } + if (count_matches == outer_ref.elements) + return TRUE + } + return FALSE +*/ + +bool subselect_table_scan_engine::partial_match() +{ + List_iterator_fast<Item> equality_it(*equi_join_conds); + Item *cur_eq; + uint count_matches; + int error; + bool res; + + tmp_table->file->ha_rnd_init(1); + tmp_table->file->extra_opt(HA_EXTRA_CACHE, + current_thd->variables.read_buff_size); + /* + TIMOUR: + scan_table() also calls "table->null_row= 0;", why, do we need it? + */ + for (;;) + { + error= tmp_table->file->ha_rnd_next(tmp_table->record[0]); + if (error) { + if (error == HA_ERR_RECORD_DELETED) + { + error= 0; + continue; + } + if (error == HA_ERR_END_OF_FILE) + { + error= 0; + break; + } + else + { + error= report_error(tmp_table, error); + break; + } + } + + equality_it.rewind(); + count_matches= 0; + while ((cur_eq= equality_it++)) + { + DBUG_ASSERT(cur_eq->type() == Item::FUNC_ITEM && + ((Item_func*)cur_eq)->functype() == Item_func::EQ_FUNC); + if (!cur_eq->val_int() && !cur_eq->null_value) + break; + ++count_matches; + } + if (count_matches == tmp_table->s->fields) + { + res= TRUE; /* Found a matching row. */ + goto end; + } + } + + res= FALSE; +end: + tmp_table->file->ha_rnd_end(); + return res; +} + + +void subselect_table_scan_engine::cleanup() +{ +} === modified file 'sql/item_subselect.h' --- a/sql/item_subselect.h 2010-02-11 23:59:58 +0000 +++ b/sql/item_subselect.h 2010-03-09 10:14:06 +0000 @@ -297,7 +297,7 @@ Representation of IN subquery predicates of the form "left_expr IN (SELECT ...)". - @detail + @details This class has: - A "subquery execution engine" (as a subclass of Item_subselect) that allows it to evaluate subqueries. (and this class participates in execution by @@ -319,6 +319,12 @@ */ List<Cached_item> *left_expr_cache; bool first_execution; + /* + Set to TRUE if at query execution time we determine that this item's + value is a constant during this execution. We need this member because + it is not possible to substitute 'this' with a constant item. + */ + bool is_constant; /* expr & optimizer used in subselect rewriting to store Item for @@ -387,8 +393,8 @@ Item_in_subselect(Item * left_expr, st_select_lex *select_lex); Item_in_subselect() :Item_exists_subselect(), left_expr_cache(0), first_execution(TRUE), - optimizer(0), abort_on_null(0), pushed_cond_guards(NULL), - exec_method(NOT_TRANSFORMED), upper_item(0) + is_constant(FALSE), optimizer(0), abort_on_null(0), + pushed_cond_guards(NULL), exec_method(NOT_TRANSFORMED), upper_item(0) {} void cleanup(); subs_type substype() { return IN_SUBS; } @@ -421,6 +427,8 @@ void update_used_tables(); bool setup_engine(); bool init_left_expr_cache(); + /* Inform 'this' that it was computed, and contains a valid result. */ + void set_first_execution() { if (first_execution) first_execution= FALSE; } bool is_expensive_processor(uchar *arg); friend class Item_ref_null_helper; @@ -428,6 +436,7 @@ friend class Item_in_optimizer; friend class subselect_indexsubquery_engine; friend class subselect_hash_sj_engine; + friend class subselect_partial_match_engine; }; @@ -462,7 +471,8 @@ enum enum_engine_type {ABSTRACT_ENGINE, SINGLE_SELECT_ENGINE, UNION_ENGINE, UNIQUESUBQUERY_ENGINE, - INDEXSUBQUERY_ENGINE, HASH_SJ_ENGINE}; + INDEXSUBQUERY_ENGINE, HASH_SJ_ENGINE, + ROWID_MERGE_ENGINE, TABLE_SCAN_ENGINE}; subselect_engine(Item_subselect *si, select_result_interceptor *res) :thd(0) @@ -635,8 +645,10 @@ virtual void print (String *str, enum_query_type query_type); bool change_result(Item_subselect *si, select_result_interceptor *result); bool no_tables(); + int index_lookup(); /* TIMOUR: this method needs refactoring. */ int scan_table(); bool copy_ref_key(); + int copy_ref_key_simple(); /* TIMOUR: this method needs refactoring. */ bool no_rows() { return empty_result_set; } virtual enum_engine_type engine_type() { return UNIQUESUBQUERY_ENGINE; } }; @@ -705,50 +717,439 @@ /** - Compute an IN predicate via a hash semi-join. The subquery is materialized - during the first evaluation of the IN predicate. The IN predicate is executed - via the functionality inherited from subselect_uniquesubquery_engine. + Compute an IN predicate via a hash semi-join. This class is responsible for + the materialization of the subquery, and the selection of the correct and + optimal execution method (e.g. direct index lookup, or partial matching) for + the IN predicate. */ -class subselect_hash_sj_engine: public subselect_uniquesubquery_engine +class subselect_hash_sj_engine : public subselect_engine { protected: + /* The table into which the subquery is materialized. */ + TABLE *tmp_table; /* TRUE if the subquery was materialized into a temp table. */ bool is_materialized; /* The old engine already chosen at parse time and stored in permanent memory. Through this member we can re-create and re-prepare materialize_join for - each execution of a prepared statement. We akso resuse the functionality + each execution of a prepared statement. We also reuse the functionality of subselect_single_select_engine::[prepare | cols]. */ subselect_single_select_engine *materialize_engine; + /* The engine used to compute the IN predicate. */ + subselect_engine *lookup_engine; /* QEP to execute the subquery and materialize its result into a temporary table. Created during the first call to exec(). */ JOIN *materialize_join; - /* Temp table context of the outer select's JOIN. */ - TMP_TABLE_PARAM *tmp_param; + + /* Keyparts of the only non-NULL composite index in a rowid merge. */ + MY_BITMAP non_null_key_parts; + /* Keyparts of the single column indexes with NULL, one keypart per index. */ + MY_BITMAP partial_match_key_parts; + uint count_partial_match_columns; + uint count_null_only_columns; + /* + A conjunction of all the equality condtions between all pairs of expressions + that are arguments of an IN predicate. We need these to post-filter some + IN results because index lookups sometimes match values that are actually + not equal to the search key in SQL terms. + */ + Item_cond_and *semi_join_conds; + /* Possible execution strategies that can be used to compute hash semi-join.*/ + enum exec_strategy { + UNDEFINED, + COMPLETE_MATCH, /* Use regular index lookups. */ + PARTIAL_MATCH, /* Use some partial matching strategy. */ + PARTIAL_MATCH_MERGE, /* Use partial matching through index merging. */ + PARTIAL_MATCH_SCAN, /* Use partial matching through table scan. */ + IMPOSSIBLE /* Subquery materialization is not applicable. */ + }; + /* The chosen execution strategy. Computed after materialization. */ + exec_strategy strategy; +protected: + exec_strategy get_strategy_using_schema(); + exec_strategy get_strategy_using_data(); + size_t rowid_merge_buff_size(bool has_non_null_key, + bool has_covering_null_row, + MY_BITMAP *partial_match_key_parts); + void choose_partial_match_strategy(bool has_non_null_key, + bool has_covering_null_row, + MY_BITMAP *partial_match_key_parts); + bool make_semi_join_conds(); + subselect_uniquesubquery_engine* make_unique_engine(); public: subselect_hash_sj_engine(THD *thd, Item_subselect *in_predicate, - subselect_single_select_engine *old_engine) - :subselect_uniquesubquery_engine(thd, NULL, in_predicate, NULL), - is_materialized(FALSE), materialize_engine(old_engine), - materialize_join(NULL), tmp_param(NULL) - {} + subselect_single_select_engine *old_engine) + :subselect_engine(in_predicate, NULL), tmp_table(NULL), + is_materialized(FALSE), materialize_engine(old_engine), lookup_engine(NULL), + materialize_join(NULL), count_partial_match_columns(0), + count_null_only_columns(0), semi_join_conds(NULL), strategy(UNDEFINED) + { + set_thd(thd); + } ~subselect_hash_sj_engine(); bool init_permanent(List<Item> *tmp_columns); bool init_runtime(); void cleanup(); - int prepare() { return 0; } + int prepare() { return 0; } /* Override virtual function in base class. */ int exec(); - virtual void print (String *str, enum_query_type query_type); + virtual void print(String *str, enum_query_type query_type); uint cols() { return materialize_engine->cols(); } + uint8 uncacheable() { return UNCACHEABLE_DEPENDENT; } + table_map upper_select_const_tables() { return 0; } + bool no_rows() { return !tmp_table->file->stats.records; } virtual enum_engine_type engine_type() { return HASH_SJ_ENGINE; } -}; - + /* + TODO: factor out all these methods in a base subselect_index_engine class + because all of them have dummy implementations and should never be called. + */ + void fix_length_and_dec(Item_cache** row);//=>base class + void exclude(); //=>base class + //=>base class + bool change_result(Item_subselect *si, select_result_interceptor *result); + bool no_tables();//=>base class +}; + + +/* + Distinguish the type od (0-based) row numbers from the type of the index into + an array of row numbers. +*/ +typedef ha_rows rownum_t; + + +/* + An Ordered_key is an in-memory table index that allows O(log(N)) time + lookups of a multi-part key. + + If the index is over a single column, then this column may contain NULLs, and + the NULLs are stored and tested separately for NULL in O(1) via is_null(). + Multi-part indexes assume that the indexed columns do not contain NULLs. + + TODO: + = Due to the unnatural assymetry between single and multi-part indexes, it + makes sense to somehow refactor or extend the class. + + = This class can be refactored into a base abstract interface, and two + subclasses: + - one to represent single-column indexes, and + - another to represent multi-column indexes. + Such separation would allow slightly more efficient implementation of + the single-column indexes. + = The current design requires such indexes to be fully recreated for each + PS (re)execution, however most of the comprising objects can be reused. +*/ + +class Ordered_key : public Sql_alloc +{ +protected: + /* + Index of the key in an array of keys. This index allows to + construct (sub)sets of keys represented by bitmaps. + */ + uint keyid; + /* The table being indexed. */ + TABLE *tbl; + /* The columns being indexed. */ + Item_field **key_columns; + /* Number of elements in 'key_columns' (number of key parts). */ + uint key_column_count; + /* + An expression, or sequence of expressions that forms the search key. + The search key is a sequence when it is Item_row. Each element of the + sequence is accessible via Item::element_index(int i). + */ + Item *search_key; + +/* Value index related members. */ + /* + The actual value index, consists of a sorted sequence of row numbers. + */ + rownum_t *key_buff; + /* Number of elements in key_buff. */ + ha_rows key_buff_elements; + /* Current element in 'key_buff'. */ + ha_rows cur_key_idx; + /* + Mapping from row numbers to row ids. The element row_num_to_rowid[i] + contains a buffer with the rowid for the row numbered 'i'. + The memory for this member is not maintanined by this class because + all Ordered_key indexes of the same table share the same mapping. + */ + uchar *row_num_to_rowid; + /* + A sequence of predicates to compare the search key with the corresponding + columns of a table row from the index. + */ + Item_func_lt **compare_pred; + +/* Null index related members. */ + MY_BITMAP null_key; + /* Count of NULLs per column. */ + ha_rows null_count; + /* The row number that contains the first NULL in a column. */ + ha_rows min_null_row; + /* The row number that contains the last NULL in a column. */ + ha_rows max_null_row; + +protected: + bool alloc_keys_buffers(); + /* + Quick sort comparison function that compares two rows of the same table + indentfied with their row numbers. + */ + int cmp_keys_by_row_data(rownum_t a, rownum_t b); + static int cmp_keys_by_row_data_and_rownum(Ordered_key *key, + rownum_t* a, rownum_t* b); + + int cmp_key_with_search_key(rownum_t row_num); + +public: + Ordered_key(uint keyid_arg, TABLE *tbl_arg, + Item *search_key_arg, ha_rows null_count_arg, + ha_rows min_null_row_arg, ha_rows max_null_row_arg, + uchar *row_num_to_rowid_arg); + ~Ordered_key(); + void cleanup(); + /* Initialize a multi-column index. */ + bool init(MY_BITMAP *columns_to_index); + /* Initialize a single-column index. */ + bool init(int col_idx); + + uint get_column_count() { return key_column_count; } + uint get_keyid() { return keyid; } + uint get_field_idx(uint i) + { + DBUG_ASSERT(i < key_column_count); + return key_columns[i]->field->field_index; + } + /* + Get the search key element that corresponds to the i-th key part of this + index. + */ + Item *get_search_key(uint i) + { + return search_key->element_index(key_columns[i]->field->field_index); + } + void add_key(rownum_t row_num) + { + /* The caller must know how many elements to add. */ + DBUG_ASSERT(key_buff_elements && cur_key_idx < key_buff_elements); + key_buff[cur_key_idx]= row_num; + ++cur_key_idx; + } + + void sort_keys(); + double null_selectivity(); + + /* + Position the current element at the first row that matches the key. + The key itself is propagated by evaluating the current value(s) of + this->search_key. + */ + bool lookup(); + /* Move the current index cursor to the first key. */ + void first() + { + DBUG_ASSERT(key_buff_elements); + cur_key_idx= 0; + } + /* TODO */ + bool next_same(); + /* Move the current index cursor to the next key. */ + bool next() + { + DBUG_ASSERT(key_buff_elements); + if (cur_key_idx < key_buff_elements - 1) + { + ++cur_key_idx; + return TRUE; + } + return FALSE; + }; + /* Return the current index element. */ + rownum_t current() + { + DBUG_ASSERT(key_buff_elements && cur_key_idx < key_buff_elements); + return key_buff[cur_key_idx]; + } + + void set_null(rownum_t row_num) + { + bitmap_set_bit(&null_key, row_num); + } + bool is_null(rownum_t row_num) + { + /* + Indexes consisting of only NULLs do not have a bitmap buffer at all. + Their only initialized member is 'n_bits', which is equal to the number + of temp table rows. + */ + if (null_count == tbl->file->stats.records) + { + DBUG_ASSERT(tbl->file->stats.records == null_key.n_bits); + return TRUE; + } + if (row_num > max_null_row || row_num < min_null_row) + return FALSE; + return bitmap_is_set(&null_key, row_num); + } + void print(String *str); +}; + + +class subselect_partial_match_engine : public subselect_engine +{ +protected: + /* The temporary table that contains a materialized subquery. */ + TABLE *tmp_table; + /* + The engine used to check whether an IN predicate is TRUE or not. If not + TRUE, then subselect_rowid_merge_engine further distinguishes between + FALSE and UNKNOWN. + */ + subselect_uniquesubquery_engine *lookup_engine; + /* A list of equalities between each pair of IN operands. */ + List<Item> *equi_join_conds; + /* + If there is a row, such that all its NULL-able components are NULL, this + member is set to the number of covered columns. If there is no covering + row, then this is 0. + */ + uint covering_null_row_width; +protected: + virtual bool partial_match()= 0; +public: + subselect_partial_match_engine(subselect_uniquesubquery_engine *engine_arg, + TABLE *tmp_table_arg, Item_subselect *item_arg, + select_result_interceptor *result_arg, + List<Item> *equi_join_conds_arg, + uint covering_null_row_width_arg); + int prepare() { return 0; } + int exec(); + void fix_length_and_dec(Item_cache**) {} + uint cols() { /* TODO: what is the correct value? */ return 1; } + uint8 uncacheable() { return UNCACHEABLE_DEPENDENT; } + void exclude() {} + table_map upper_select_const_tables() { return 0; } + bool change_result(Item_subselect*, select_result_interceptor*) + { DBUG_ASSERT(FALSE); return false; } + bool no_tables() { return false; } + bool no_rows() + { + /* + TODO: It is completely unclear what is the semantics of this + method. The current result is computed so that the call to no_rows() + from Item_in_optimizer::val_int() sets Item_in_optimizer::null_value + correctly. + */ + return !(((Item_in_subselect *) item)->null_value); + } + void print(String*, enum_query_type); + + friend void subselect_hash_sj_engine::cleanup(); +}; + + +class subselect_rowid_merge_engine: public subselect_partial_match_engine +{ +protected: + /* + Mapping from row numbers to row ids. The rowids are stored sequentially + in the array - rowid[i] is located in row_num_to_rowid + i * rowid_length. + */ + uchar *row_num_to_rowid; + /* + A subset of all the keys for which there is a match for the same row. + Used during execution. Computed for each outer reference + */ + MY_BITMAP matching_keys; + /* + The columns of the outer reference that are NULL. Computed for each + outer reference. + */ + MY_BITMAP matching_outer_cols; + /* + Columns that consist of only NULLs. Such columns match any value. + Computed once per query execution. + */ + MY_BITMAP null_only_columns; + /* + Indexes of row numbers, sorted by <column_value, row_number>. If an + index may contain NULLs, the NULLs are stored efficiently in a bitmap. + + The indexes are sorted by the selectivity of their NULL sub-indexes, the + one with the fewer NULLs is first. Thus, if there is any index on + non-NULL columns, it is contained in keys[0]. + */ + Ordered_key **merge_keys; + /* The number of elements in keys. */ + uint keys_count; + /* + An index on all non-NULL columns of 'tmp_table'. The index has the + logical form: <[v_i1 | ... | v_ik], rownum>. It allows to find the row + number where the columns c_i1,...,c1_k contain the values v_i1,...,v_ik. + If such an index exists, it is always the first element of 'keys'. + */ + Ordered_key *non_null_key; + /* + Priority queue of Ordered_key indexes, one per NULLable column. + This queue is used by the partial match algorithm in method exec(). + */ + QUEUE pq; +protected: + /* + Comparison function to compare keys in order of decreasing bitmap + selectivity. + */ + static int cmp_keys_by_null_selectivity(Ordered_key **k1, Ordered_key **k2); + /* + Comparison function used by the priority queue pq, the 'smaller' key + is the one with the smaller current row number. + */ + static int cmp_keys_by_cur_rownum(void *arg, uchar *k1, uchar *k2); + + bool test_null_row(rownum_t row_num); + bool partial_match(); +public: + subselect_rowid_merge_engine(subselect_uniquesubquery_engine *engine_arg, + TABLE *tmp_table_arg, uint keys_count_arg, + uint covering_null_row_width_arg, + Item_subselect *item_arg, + select_result_interceptor *result_arg, + List<Item> *equi_join_conds_arg) + :subselect_partial_match_engine(engine_arg, tmp_table_arg, item_arg, + result_arg, equi_join_conds_arg, + covering_null_row_width_arg), + keys_count(keys_count_arg), non_null_key(NULL) + { + thd= lookup_engine->get_thd(); + } + ~subselect_rowid_merge_engine(); + bool init(MY_BITMAP *non_null_key_parts, MY_BITMAP *partial_match_key_parts); + void cleanup(); + virtual enum_engine_type engine_type() { return ROWID_MERGE_ENGINE; } +}; + + +class subselect_table_scan_engine: public subselect_partial_match_engine +{ +protected: + bool partial_match(); +public: + subselect_table_scan_engine(subselect_uniquesubquery_engine *engine_arg, + TABLE *tmp_table_arg, Item_subselect *item_arg, + select_result_interceptor *result_arg, + List<Item> *equi_join_conds_arg, + uint covering_null_row_width_arg); + void cleanup(); + virtual enum_engine_type engine_type() { return TABLE_SCAN_ENGINE; } +}; === modified file 'sql/mysql_priv.h' --- a/sql/mysql_priv.h 2010-01-17 14:55:08 +0000 +++ b/sql/mysql_priv.h 2010-03-09 10:14:06 +0000 @@ -552,12 +552,14 @@ #define OPTIMIZER_SWITCH_LOOSE_SCAN 64 #define OPTIMIZER_SWITCH_MATERIALIZATION 128 #define OPTIMIZER_SWITCH_SEMIJOIN 256 +#define OPTIMIZER_SWITCH_PARTIAL_MATCH_ROWID_MERGE 512 +#define OPTIMIZER_SWITCH_PARTIAL_MATCH_TABLE_SCAN 1024 #ifdef DBUG_OFF -# define OPTIMIZER_SWITCH_LAST 512 +# define OPTIMIZER_SWITCH_LAST 2048 #else -# define OPTIMIZER_SWITCH_TABLE_ELIMINATION 512 -# define OPTIMIZER_SWITCH_LAST 1024 +# define OPTIMIZER_SWITCH_TABLE_ELIMINATION 2048 +# define OPTIMIZER_SWITCH_LAST 4096 #endif #ifdef DBUG_OFF @@ -570,8 +572,10 @@ OPTIMIZER_SWITCH_FIRSTMATCH | \ OPTIMIZER_SWITCH_LOOSE_SCAN | \ OPTIMIZER_SWITCH_MATERIALIZATION | \ - OPTIMIZER_SWITCH_SEMIJOIN) -#else + OPTIMIZER_SWITCH_SEMIJOIN | \ + OPTIMIZER_SWITCH_PARTIAL_MATCH_ROWID_MERGE|\ + OPTIMIZER_SWITCH_PARTIAL_MATCH_TABLE_SCAN) +#else # define OPTIMIZER_SWITCH_DEFAULT (OPTIMIZER_SWITCH_INDEX_MERGE | \ OPTIMIZER_SWITCH_INDEX_MERGE_UNION | \ OPTIMIZER_SWITCH_INDEX_MERGE_SORT_UNION | \ @@ -581,7 +585,9 @@ OPTIMIZER_SWITCH_FIRSTMATCH | \ OPTIMIZER_SWITCH_LOOSE_SCAN | \ OPTIMIZER_SWITCH_MATERIALIZATION | \ - OPTIMIZER_SWITCH_SEMIJOIN) + OPTIMIZER_SWITCH_SEMIJOIN | \ + OPTIMIZER_SWITCH_PARTIAL_MATCH_ROWID_MERGE|\ + OPTIMIZER_SWITCH_PARTIAL_MATCH_TABLE_SCAN) #endif /* === modified file 'sql/mysqld.cc' --- a/sql/mysqld.cc 2010-01-17 14:55:08 +0000 +++ b/sql/mysqld.cc 2010-03-09 10:14:06 +0000 @@ -301,7 +301,9 @@ "index_merge","index_merge_union","index_merge_sort_union", "index_merge_intersection", "index_condition_pushdown", - "firstmatch","loosescan","materialization", "semijoin", + "firstmatch","loosescan","materialization", "semijoin", + "partial_match_rowid_merge", + "partial_match_table_scan", #ifndef DBUG_OFF "table_elimination", #endif @@ -320,6 +322,8 @@ sizeof("loosescan") - 1, sizeof("materialization") - 1, sizeof("semijoin") - 1, + sizeof("partial_match_rowid_merge") - 1, + sizeof("partial_match_table_scan") - 1, #ifndef DBUG_OFF sizeof("table_elimination") - 1, #endif @@ -5794,7 +5798,8 @@ OPT_RECORD_RND_BUFFER, OPT_DIV_PRECINCREMENT, OPT_RELAY_LOG_SPACE_LIMIT, OPT_RELAY_LOG_PURGE, OPT_SLAVE_NET_TIMEOUT, OPT_SLAVE_COMPRESSED_PROTOCOL, OPT_SLOW_LAUNCH_TIME, - OPT_SLAVE_TRANS_RETRIES, OPT_READONLY, OPT_DEBUGGING, OPT_DEBUG_FLUSH, + OPT_SLAVE_TRANS_RETRIES, OPT_READONLY, OPT_ROWID_MERGE_BUFF_SIZE, + OPT_DEBUGGING, OPT_DEBUG_FLUSH, OPT_SORT_BUFFER, OPT_TABLE_OPEN_CACHE, OPT_TABLE_DEF_CACHE, OPT_THREAD_CONCURRENCY, OPT_THREAD_CACHE_SIZE, OPT_TMP_TABLE_SIZE, OPT_THREAD_STACK, @@ -7130,6 +7135,11 @@ (uchar**) &max_system_variables.range_alloc_block_size, 0, GET_ULONG, REQUIRED_ARG, RANGE_ALLOC_BLOCK_SIZE, RANGE_ALLOC_BLOCK_SIZE, (longlong) ULONG_MAX, 0, 1024, 0}, + {"rowid_merge_buff_size", OPT_ROWID_MERGE_BUFF_SIZE, + "The size of the buffers used [NOT] IN evaluation via partial matching.", + (uchar**) &global_system_variables.rowid_merge_buff_size, + (uchar**) &max_system_variables.rowid_merge_buff_size, 0, GET_ULONG, + REQUIRED_ARG, 8*1024*1024L, 0, MAX_MEM_TABLE_SIZE/2, 0, 1, 0}, {"read_buffer_size", OPT_RECORD_BUFFER, "Each thread that does a sequential scan allocates a buffer of this size for each table it scans. If you do many sequential scans, you may want to increase this value.", (uchar**) &global_system_variables.read_buff_size, === modified file 'sql/opt_subselect.cc' --- a/sql/opt_subselect.cc 2010-03-15 06:32:54 +0000 +++ b/sql/opt_subselect.cc 2010-03-15 15:09:35 +0000 @@ -187,10 +187,10 @@ does not call setup_subquery_materialization(). We could make SELECT ... FROM DUAL call that function but that doesn't seem to be the case that is worth handling. - 4. Subquery predicate is a top-level predicate - (this implies it is not negated) - TODO: this is a limitation that should be lifted once we - implement correct NULL semantics (WL#3830) + 4. Either the subquery predicate is a top-level predicate, or at + least one partial match strategy is enabled. If no partial match + strategy is enabled, then materialization cannot be used for + non-top-level queries because it cannot handle NULLs correctly. 5. Subquery is non-correlated TODO: This is an overly restrictive condition. It can be extended to: @@ -204,8 +204,8 @@ (*) The subquery must be part of a SELECT statement. The current condition also excludes multi-table update statements. - We have to determine whether we will perform subquery materialization - before calling the IN=>EXISTS transformation, so that we know whether to + Determine whether we will perform subquery materialization before + calling the IN=>EXISTS transformation, so that we know whether to perform the whole transformation or only that part of it which wraps Item_in_subselect in an Item_in_optimizer. */ @@ -215,12 +215,14 @@ select_lex->master_unit()->first_select()->leaf_tables && // 3 thd->lex->sql_command == SQLCOM_SELECT && // * select_lex->outer_select()->leaf_tables && // 3A - subquery_types_allow_materialization(in_subs)) + subquery_types_allow_materialization(in_subs) && + // psergey-todo: duplicated_subselect_card_check: where it's done? + (in_subs->is_top_level_item() || + optimizer_flag(thd, OPTIMIZER_SWITCH_PARTIAL_MATCH_ROWID_MERGE) || + optimizer_flag(thd, OPTIMIZER_SWITCH_PARTIAL_MATCH_TABLE_SCAN)) &&//4 + !in_subs->is_correlated && // 5 + in_subs->exec_method == Item_in_subselect::NOT_TRANSFORMED) // 6 { - // psergey-todo: duplicated_subselect_card_check: where it's done? - if (in_subs->is_top_level_item() && // 4 - !in_subs->is_correlated && // 5 - in_subs->exec_method == Item_in_subselect::NOT_TRANSFORMED) // 6 in_subs->exec_method= Item_in_subselect::MATERIALIZATION; } === modified file 'sql/set_var.cc' --- a/sql/set_var.cc 2009-12-22 12:49:15 +0000 +++ b/sql/set_var.cc 2010-03-09 10:14:06 +0000 @@ -540,6 +540,9 @@ static sys_var_thd_ulong sys_range_alloc_block_size(&vars, "range_alloc_block_size", &SV::range_alloc_block_size); +static sys_var_thd_ulong sys_rowid_merge_buff_size(&vars, "rowid_merge_buff_size", + &SV::rowid_merge_buff_size); + static sys_var_thd_ulong sys_query_alloc_block_size(&vars, "query_alloc_block_size", &SV::query_alloc_block_size, 0, fix_thd_mem_root); === modified file 'sql/sql_class.cc' --- a/sql/sql_class.cc 2010-02-17 21:59:41 +0000 +++ b/sql/sql_class.cc 2010-02-19 21:55:57 +0000 @@ -42,6 +42,7 @@ #include "sp_rcontext.h" #include "sp_cache.h" +#include "sql_select.h" /* declares create_tmp_table() */ /* The following is used to initialise Table_ident with a internal @@ -2877,6 +2878,71 @@ return 0; } + +bool +select_materialize_with_stats:: +create_result_table(THD *thd_arg, List<Item> *column_types, + bool is_union_distinct, ulonglong options, + const char *table_alias, bool bit_fields_as_long) +{ + DBUG_ASSERT(table == 0); + tmp_table_param.field_count= column_types->elements; + tmp_table_param.bit_fields_as_long= bit_fields_as_long; + + if (! (table= create_tmp_table(thd_arg, &tmp_table_param, *column_types, + (ORDER*) 0, is_union_distinct, 1, + options, HA_POS_ERROR, (char*) table_alias))) + return TRUE; + + col_stat= (Column_statistics*) table->in_use->alloc(table->s->fields * + sizeof(Column_statistics)); + if (!stat) + return TRUE; + + cleanup(); + + table->file->extra(HA_EXTRA_WRITE_CACHE); + table->file->extra(HA_EXTRA_IGNORE_DUP_KEY); + return FALSE; +} + + +/** + Override select_union::send_data to analyze each row for NULLs and to + update null_statistics before sending data to the client. + + @return TRUE if fatal error when sending data to the client + @return FALSE on success +*/ + +bool select_materialize_with_stats::send_data(List<Item> &items) +{ + List_iterator_fast<Item> item_it(items); + Item *cur_item; + Column_statistics *cur_col_stat= col_stat; + uint nulls_in_row= 0; + + ++count_rows; + + while ((cur_item= item_it++)) + { + if (cur_item->is_null()) + { + ++cur_col_stat->null_count; + cur_col_stat->max_null_row= count_rows; + if (!cur_col_stat->min_null_row) + cur_col_stat->min_null_row= count_rows; + ++nulls_in_row; + } + ++cur_col_stat; + } + if (nulls_in_row > max_nulls_in_row) + max_nulls_in_row= nulls_in_row; + + return select_union::send_data(items); +} + + /**************************************************************************** TMP_TABLE_PARAM ****************************************************************************/ === modified file 'sql/sql_class.h' --- a/sql/sql_class.h 2010-02-17 21:59:41 +0000 +++ b/sql/sql_class.h 2010-03-09 10:14:06 +0000 @@ -343,6 +343,8 @@ ulong mrr_buff_size; ulong div_precincrement; ulong sortbuff_size; + /* Total size of all buffers used by the subselect_rowid_merge_engine. */ + ulong rowid_merge_buff_size; ulong thread_handling; ulong tx_isolation; ulong completion_type; @@ -2740,19 +2742,20 @@ class select_union :public select_result_interceptor { +protected: TMP_TABLE_PARAM tmp_table_param; public: TABLE *table; - select_union() :table(0) {} + select_union() :table(0) { tmp_table_param.init(); } int prepare(List<Item> &list, SELECT_LEX_UNIT *u); bool send_data(List<Item> &items); bool send_eof(); bool flush(); - bool create_result_table(THD *thd, List<Item> *column_types, - bool is_distinct, ulonglong options, - const char *alias, bool bit_fields_as_long); + virtual bool create_result_table(THD *thd, List<Item> *column_types, + bool is_distinct, ulonglong options, + const char *alias, bool bit_fields_as_long); }; /* Base subselect interface class */ @@ -2776,6 +2779,74 @@ bool send_data(List<Item> &items); }; + +/* + This class specializes select_union to collect statistics about the + data stored in the temp table. Currently the class collects statistcs + about NULLs. +*/ + +class select_materialize_with_stats : public select_union +{ +protected: + class Column_statistics + { + public: + /* Count of NULLs per column. */ + ha_rows null_count; + /* The row number that contains the first NULL in a column. */ + ha_rows min_null_row; + /* The row number that contains the last NULL in a column. */ + ha_rows max_null_row; + }; + + /* Array of statistics data per column. */ + Column_statistics* col_stat; + + /* + The number of columns in the biggest sub-row that consists of only + NULL values. + */ + ha_rows max_nulls_in_row; + /* + Count of rows writtent to the temp table. This is redundant as it is + already stored in handler::stats.records, however that one is relatively + expensive to compute (given we need that for evry row). + */ + ha_rows count_rows; + +public: + select_materialize_with_stats() {} + virtual bool create_result_table(THD *thd, List<Item> *column_types, + bool is_distinct, ulonglong options, + const char *alias, bool bit_fields_as_long); + bool init_result_table(ulonglong select_options); + bool send_data(List<Item> &items); + void cleanup() + { + memset(col_stat, 0, table->s->fields * sizeof(Column_statistics)); + max_nulls_in_row= 0; + count_rows= 0; + } + ha_rows get_null_count_of_col(uint idx) + { + DBUG_ASSERT(idx < table->s->fields); + return col_stat[idx].null_count; + } + ha_rows get_max_null_of_col(uint idx) + { + DBUG_ASSERT(idx < table->s->fields); + return col_stat[idx].max_null_row; + } + ha_rows get_min_null_of_col(uint idx) + { + DBUG_ASSERT(idx < table->s->fields); + return col_stat[idx].min_null_row; + } + ha_rows get_max_nulls_in_row() { return max_nulls_in_row; } +}; + + /* used in independent ALL/ANY optimisation */ class select_max_min_finder_subselect :public select_subselect { === modified file 'sql/sql_select.cc' --- a/sql/sql_select.cc 2010-03-14 18:25:43 +0000 +++ b/sql/sql_select.cc 2010-03-15 14:34:56 +0000 @@ -874,6 +874,9 @@ { DBUG_PRINT("info",("No tables")); error= 0; + /* Create all structures needed for materialized subquery execution. */ + if (setup_subquery_materialization()) + DBUG_RETURN(1); DBUG_RETURN(0); } error= -1; // Error is sent to client @@ -11258,7 +11261,7 @@ param->group_buff=group_buff; share->keys=1; share->uniques= test(using_unique_constraint); - table->key_info=keyinfo; + table->key_info= table->s->key_info= keyinfo; keyinfo->key_part=key_part_info; keyinfo->flags=HA_NOSAME; keyinfo->usable_key_parts=keyinfo->key_parts= param->group_parts; @@ -11344,7 +11347,7 @@ keyinfo->key_parts * sizeof(KEY_PART_INFO)))) goto err; bzero((void*) key_part_info, keyinfo->key_parts * sizeof(KEY_PART_INFO)); - table->key_info=keyinfo; + table->key_info= table->s->key_info= keyinfo; keyinfo->key_part=key_part_info; keyinfo->flags=HA_NOSAME | HA_NULL_ARE_EQUAL; keyinfo->key_length= 0; // Will compute the sum of the parts below.

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Re: [Maria-developers] options for CREATE TABLE (MWL#43)
by Michael Widenius 15 Mar '10

15 Mar '10

Hi! >>>>> "Sergei" == Sergei Golubchik <serg(a)askmonty.org> writes: <cut> >>> 2. Unknown option should be an error by default. >> >> OK. The only problem is that it is contradict to Monty requirements. >> Our initial decision was issue error if option was added explicitly. >> The only problem is that it is very difficult to implement - we write >> options to .frm first then read them and pass to engine. I have no >> idea how to pass this information via/over frm. Sergei> I hope you've seen my reasoning below about optimizing for a common Sergei> case. Monty wants boundary cases to work - like changing engines back Sergei> and forth and replication. I am saying that by default unknown options Sergei> should be an error, but one should be able to disable that. Sergei> "An error if opion as added explicitly" does not solve all boundary Sergei> cases, for example, restoring a dump into a different engine. Sergei> Monty would probably want to cover that too. As almost all options are just 'extra information', I prefer that by default one doesn't get an error if the engine doesn't recognize the option. This is otherwise it's hell for automatic create table tools to work. It's much easier if one can just choose engine and then different options, some which are supported and others that may not be supported. Otherwise each tool would need to have a list of all existing engines and what options each support, which would be real hell. >>> 3. use something my_getopt-like as we discussed, don't force every >>> engine to parse its options >> >> I can add such function for users to use, but it will be thier choice >> use it or do not, is it OK? Sergei> What was the problem with doing it automatically ? Beccause the engine will still needs to do a switch over all options it supports, so it's hard to do it automatically. >>> 4. make options immutable to avoid copying them in ::clone >> >> I do not know way to do it if they should be allocated in different >> mem_roots. Sergei> Example ? Where are they allocated in different memroots ? This should work if we create the new table and reopen it before the old table is closed (which should be the case). >>> 5. don't check for changed options in alter table with your >>> check_if_incompatible_data. let the engine do that. >> >> This and 8 require big changes engine and ALTER TABLE. Monty's >> requirement was do not touch current code. I would be glad if you >> discuss it and make some non contradicting requirement. No comments, but I think this is easier to do on the top level than in the engine (but I don't remember Sanjas code exactly regarding this). >>> 7. parser: make the equal sign optional >> >> I have some doubts that it is doable >> >> DATA DIRECTORY TEST VALUE ... >> >> Does it mean: >> >> DATA = DIRECTORY TEST = VALUE ... >> >> or >> >> DATA DIRECTORY = TEST VALUE ... ? - error >> (ALTER TABLE uses create_table_options_space_separated list of options) Sergei> did you try the code from my previous email ? Agree with sanja that not having = can lead to parse problems. Also using = is more readable so I would prefer to over time start deprecate space between keyword and value. <cut> >>>> === modified file 'sql/sql_table.cc' >>>> --- sql/sql_table.cc 2010-02-12 08:47:31 +0000 >>>> +++ sql/sql_table.cc 2010-03-04 20:46:55 +0000 >>>> @@ -5789,6 +5791,15 @@ compare_tables(TABLE *table, >>>> DBUG_RETURN(0); >>>> } >>>> >>>> + if (!is_equal_create_options(tmp_new_field->create_options.first, >>>> + field->create_options.first)) >>>> + { >>> >>> I am not sure this should be checked on MySQL level, we don't know the >>> semantics of options. I'd say this check belong to >>> handler::check_if_incompatible_data() and should be implemented in the >>> storage engine internally. >> >> Monty even requested me to recreate .frm even if case of KEY was chenged >> (which is clear do not chengr semantic) - i.e. any change == rewriting >> .frm. So your requests contradict here it should be discussed (I do not see >> sens nor harm in such rewriting policy) Sergei> recreating frm is one thing, doing a full alter with copying the data is Sergei> another. I'm saying that it's not MySQL that should decide what change Sergei> in table options requires copy_data_between_tables - but the engine Sergei> itself. Agree that it's only the engine that knows if we need to copy the data or not. >>>> +plugin_option_value: >>>> + DEFAULT >>>> + { >>>> + $$.str= NULL; /* We are going to remove the option */ >>>> + $$.length= 0; >>>> + } >>>> + | NULL_SYM >>> >>> I don't like this trick. >>> If you don't support NULLs, dont't allow users to specify them >> >> how it can be stored as parameter value? Such semantic prevent users of >> thinking that assigning NULL will make it really NULL not "NULL". Sergei> It won't be "NULL", IDENT_sys that you use in plugin_option_value Sergei> will not treat NULL as an ident. I think if you simply remove Sergei> NULL alternative from the plugin_option_value rule, you'll end up Sergei> having a syntax error for option=NULL, which is better than what you Sergei> have now. Ok with me that we delete the =NULL syntax to remove options. >>>> +++ sql/sql_create_options.cc 2010-03-04 20:46:55 +0000 >>>> +my_bool create_option_add(CREATE_OPTION_LIST *options, MEM_ROOT *root, >>>> + const LEX_STRING *str_key, >>>> + const LEX_STRING *str_val, >>>> + my_bool *changed) >>>> +{ >>>> + CREATE_OPTION *cur_option, **option; >>>> + char *key, *val; >>>> + my_bool not_used; >>>> + my_bool copy= FALSE; >>>> + my_bool replace= FALSE; >>>> + DBUG_ENTER("create_option_add"); >>>> + DBUG_PRINT("enter", ("key: '%s' value: '%s'", >>>> + str_key->str, str_val->str)); >>>> + if (changed) >>>> + copy= TRUE; >>>> + else >>>> + changed= &not_used; >>>> + >>>> + DBUG_ASSERT(options->first || >>>> + (!options->first && options->last == &options->first)); >>>> + *changed= FALSE; >>> >>> Hmm, strange. From the way you use 'changed' I thought it should >>> accumulate >>> the results - I mean, it's one variable that is passed into >>> create_option_add() for all options. Apparently at the end it should be >>> true if *any* of the options has changed. >>> >>> But then, why do you set it to false inside create_option_add() ? >> >> It was special case for call from ALTER TABLE and from parser. Only ALTER >> TABLE was interested in changes and so required copying parameters. Sergei> I don't understand. I also in my review thought it would be much more logical if 'changed' would be reset (if needed) on the outer level, not in the function. >>>> + >>>> + /* try to find the option first */ >>>> + for (option= &(options->first); >>>> + *option && my_strcasecmp(system_charset_info, >>>> + str_key->str, (*option)->key.str); >>>> + option= &((*option)->next)) ; >>>> + if (str_val->str) >>>> + { >>>> + /* add / replace */ >>>> + if (*option) >>>> + { >>>> + /* replace */ >>>> + cur_option= *option; >>>> + if (!(*changed) && >>>> + (cur_option->val.length != str_val->length || >>>> + memcmp(cur_option->val.str, str_val->str, str_val->length))) >>>> + { >>>> + *changed= TRUE; >>>> + } >>>> + replace= TRUE; >>>> + } >>>> + else >>>> + { Sergei> ... >>>> +CREATE_OPTION_LIST *create_create_options_array(MEM_ROOT *root, uint n) >>> >>> "create_create" is not a good name :( >> >> I did not found better but open for suggestion. Sergei> make_create_options_array ? Sergei> construct_create_options_array ? construct_create_options_array sounds nice to me. >>>> +my_bool create_options_read(const uchar *buff, uint length, MEM_ROOT >>>> *root, >>>> + TABLE_OPTIONS *opt) >>>> +{ >>>> + const uchar *buff_end= buff + length; >>>> + DBUG_ENTER("create_options_read"); >>>> + while (buff < buff_end) >>>> + { >>>> + CREATE_OPTION *option; >>>> + CREATE_OPTION_TYPES type; >>>> + uint index= 0; >>>> + >>>> + if (!(option= (CREATE_OPTION *) alloc_root(root, >>>> sizeof(CREATE_OPTION)))) >>>> + DBUG_RETURN(TRUE); >>>> + >>>> + DBUG_ASSERT(buff + 4 <= buff_end); >>>> + option->val.length= uint2korr(buff); >>>> + option->key.length= buff[2]; >>>> + option->next= NULL; >>>> + type= (CREATE_OPTION_TYPES)buff[3]; >>>> + buff+= 4; >>>> + switch (type) { >>>> + case CREATE_OPTION_FIELD: >>> >>> interesting encoding. so basically you support the case when field, >>> key, and table options are all written interleaved: >>> >>> <table option><key 1 option><field 5 option><table option><field 3 option> <key 4 option>... >>> >>> why the heck do you want to support it ? >> >> Could you propose other encoding taking into account that some fields, keys >> and tables do not have parameters and some has several ones? Sergei> Sure. Many :) Sergei> For example Sergei> <number of table options> Sergei> <length-encoded strings for table options> Sergei> <number of field 1 options> Sergei> <length-encoded strings for field 1 options> Sergei> <number of field 2 options> Sergei> <length-encoded strings for field 2 options> Sergei> ... Sergei> <number of key 1 options> Sergei> <length-encoded strings for key 1 options> Sergei> <number of key 2 options> Sergei> <length-encoded strings for key 2 options> Sergei> Assuming a table with three fields and two keys that would be Sergei> 0x02 0x05 "topt1" 0x03 "val" 0x03 "to2" 0x04 "val2" Sergei> 0x00 Sergei> 0x01 0x04 "fil1" 0x01 "1" Sergei> 0x03 0x01 "A" 0x02 "bb" 0x01 "B" 0x02 "CC" 0x02 "de" 0x01 "0" Sergei> 0x01 0x06 "packed" 0x03 "yes" Sergei> 0x00 I also originally thought about this (I would probably have stored things the above way if I would have coded this). However, I am not sure that the code would be shorter than Sanjas code. The fact that the code can handle cases that never happens in reality didn't bother me. Regards, Monty

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[Maria-developers] Progress (by Knielsen): New replication APIs (107)
by worklog-noreply＠askmonty.org 15 Mar '10

15 Mar '10

----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: New replication APIs CREATION DATE..: Mon, 15 Mar 2010, 13:55 SUPERVISOR.....: Knielsen IMPLEMENTOR....: Knielsen COPIES TO......: Sergei CATEGORY.......: Server-Sprint TASK ID........: 107 (http://askmonty.org/worklog/?tid=107) VERSION........: Server-9.x STATUS.........: Un-Assigned PRIORITY.......: 60 WORKED HOURS...: 25 ESTIMATE.......: 0 (hours remain) ORIG. ESTIMATE.: 0 PROGRESS NOTES: -=-=(Knielsen - Mon, 15 Mar 2010, 14:28)=-=- Research into the problem, and discussions on phone/mailing list Worked 25 hours and estimate 0 hours remain (original estimate increased by 25 hours). -=-=(Guest - Mon, 15 Mar 2010, 14:18)=-=- High-Level Specification modified. --- /tmp/wklog.107.old.9086 2010-03-15 14:18:18.000000000 +0000 +++ /tmp/wklog.107.new.9086 2010-03-15 14:18:18.000000000 +0000 @@ -1 +1,43 @@ +Current ideas/status after discussions on the mailing list: + + - Implement a set of plugin APIs and use them to move all of the existing + MySQL replication into a (set of) plugins. + + - Design the APIs so that they can support full MySQL replication, but also + so that they do not hardcode assumptions about how this replication + implementation is done, and so that they will be suitable for other types of + replication (Tungsten, Galera, parallel replication, ...). + + - APIs need to include the concept of a global transaction ID. Need to + determine the extent to which the semantics of such ID will be defined + by the API, and to which extend it will be defined by the plugin + implementations. + + - APIs should properly support reliable crash-recovery with decent + performance (eg. not require multiple mandatory fsync()s per commit, and + not make group commit impossible). + + - Would be nice if the API provided facilities for implementing good + consistency checking support (mainly checking master tables against slave + tables is hard here I think, but also applying wrong binlog data and + individual event checksums). + + +Steps to make this more concrete: + + - Investigate the current MySQL replication, and list all of the places where + a plugin implementation will need to connect/hook into the MySQL server. + * handler::{write,update,delete}_row() + * Statement execution + * Transaction start/commit + * Table open + * Query safe/not/safe for statement based replication + * Statement-based logging details (user variables, random seed, etc.) + * ... + + - Use this list to make an initial sketch of the set of APIs we need. + + - Use the list to determine the feasibility of this project and the level of + detail in the API needed to support a full replication implementation as a + plugin. -=-=(Serg - Mon, 15 Mar 2010, 14:13)=-=- Observers changed: Sergei DESCRIPTION: This is a top-level task for the project of designing a new set of replication APIs for MariaDB. This task is for the initial discussion of what to do and where to focus. The project is started in this email thread: https://lists.launchpad.net/maria-developers/msg01998.html HIGH-LEVEL SPECIFICATION: Current ideas/status after discussions on the mailing list: - Implement a set of plugin APIs and use them to move all of the existing MySQL replication into a (set of) plugins. - Design the APIs so that they can support full MySQL replication, but also so that they do not hardcode assumptions about how this replication implementation is done, and so that they will be suitable for other types of replication (Tungsten, Galera, parallel replication, ...). - APIs need to include the concept of a global transaction ID. Need to determine the extent to which the semantics of such ID will be defined by the API, and to which extend it will be defined by the plugin implementations. - APIs should properly support reliable crash-recovery with decent performance (eg. not require multiple mandatory fsync()s per commit, and not make group commit impossible). - Would be nice if the API provided facilities for implementing good consistency checking support (mainly checking master tables against slave tables is hard here I think, but also applying wrong binlog data and individual event checksums). Steps to make this more concrete: - Investigate the current MySQL replication, and list all of the places where a plugin implementation will need to connect/hook into the MySQL server. * handler::{write,update,delete}_row() * Statement execution * Transaction start/commit * Table open * Query safe/not/safe for statement based replication * Statement-based logging details (user variables, random seed, etc.) * ... - Use this list to make an initial sketch of the set of APIs we need. - Use the list to determine the feasibility of this project and the level of detail in the API needed to support a full replication implementation as a plugin. ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v3.5.9)

1 0

[Maria-developers] Progress (by Knielsen): New replication APIs (107)
by worklog-noreply＠askmonty.org 15 Mar '10

15 Mar '10

----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: New replication APIs CREATION DATE..: Mon, 15 Mar 2010, 13:55 SUPERVISOR.....: Knielsen IMPLEMENTOR....: Knielsen COPIES TO......: Sergei CATEGORY.......: Server-Sprint TASK ID........: 107 (http://askmonty.org/worklog/?tid=107) VERSION........: Server-9.x STATUS.........: Un-Assigned PRIORITY.......: 60 WORKED HOURS...: 25 ESTIMATE.......: 0 (hours remain) ORIG. ESTIMATE.: 0 PROGRESS NOTES: -=-=(Knielsen - Mon, 15 Mar 2010, 14:28)=-=- Research into the problem, and discussions on phone/mailing list Worked 25 hours and estimate 0 hours remain (original estimate increased by 25 hours). -=-=(Guest - Mon, 15 Mar 2010, 14:18)=-=- High-Level Specification modified. --- /tmp/wklog.107.old.9086 2010-03-15 14:18:18.000000000 +0000 +++ /tmp/wklog.107.new.9086 2010-03-15 14:18:18.000000000 +0000 @@ -1 +1,43 @@ +Current ideas/status after discussions on the mailing list: + + - Implement a set of plugin APIs and use them to move all of the existing + MySQL replication into a (set of) plugins. + + - Design the APIs so that they can support full MySQL replication, but also + so that they do not hardcode assumptions about how this replication + implementation is done, and so that they will be suitable for other types of + replication (Tungsten, Galera, parallel replication, ...). + + - APIs need to include the concept of a global transaction ID. Need to + determine the extent to which the semantics of such ID will be defined + by the API, and to which extend it will be defined by the plugin + implementations. + + - APIs should properly support reliable crash-recovery with decent + performance (eg. not require multiple mandatory fsync()s per commit, and + not make group commit impossible). + + - Would be nice if the API provided facilities for implementing good + consistency checking support (mainly checking master tables against slave + tables is hard here I think, but also applying wrong binlog data and + individual event checksums). + + +Steps to make this more concrete: + + - Investigate the current MySQL replication, and list all of the places where + a plugin implementation will need to connect/hook into the MySQL server. + * handler::{write,update,delete}_row() + * Statement execution + * Transaction start/commit + * Table open + * Query safe/not/safe for statement based replication + * Statement-based logging details (user variables, random seed, etc.) + * ... + + - Use this list to make an initial sketch of the set of APIs we need. + + - Use the list to determine the feasibility of this project and the level of + detail in the API needed to support a full replication implementation as a + plugin. -=-=(Serg - Mon, 15 Mar 2010, 14:13)=-=- Observers changed: Sergei DESCRIPTION: This is a top-level task for the project of designing a new set of replication APIs for MariaDB. This task is for the initial discussion of what to do and where to focus. The project is started in this email thread: https://lists.launchpad.net/maria-developers/msg01998.html HIGH-LEVEL SPECIFICATION: Current ideas/status after discussions on the mailing list: - Implement a set of plugin APIs and use them to move all of the existing MySQL replication into a (set of) plugins. - Design the APIs so that they can support full MySQL replication, but also so that they do not hardcode assumptions about how this replication implementation is done, and so that they will be suitable for other types of replication (Tungsten, Galera, parallel replication, ...). - APIs need to include the concept of a global transaction ID. Need to determine the extent to which the semantics of such ID will be defined by the API, and to which extend it will be defined by the plugin implementations. - APIs should properly support reliable crash-recovery with decent performance (eg. not require multiple mandatory fsync()s per commit, and not make group commit impossible). - Would be nice if the API provided facilities for implementing good consistency checking support (mainly checking master tables against slave tables is hard here I think, but also applying wrong binlog data and individual event checksums). Steps to make this more concrete: - Investigate the current MySQL replication, and list all of the places where a plugin implementation will need to connect/hook into the MySQL server. * handler::{write,update,delete}_row() * Statement execution * Transaction start/commit * Table open * Query safe/not/safe for statement based replication * Statement-based logging details (user variables, random seed, etc.) * ... - Use this list to make an initial sketch of the set of APIs we need. - Use the list to determine the feasibility of this project and the level of detail in the API needed to support a full replication implementation as a plugin. ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v3.5.9)

1 0

[Maria-developers] Updated (by Guest): New replication APIs (107)
by worklog-noreply＠askmonty.org 15 Mar '10

15 Mar '10

----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: New replication APIs CREATION DATE..: Mon, 15 Mar 2010, 13:55 SUPERVISOR.....: Knielsen IMPLEMENTOR....: Knielsen COPIES TO......: Sergei CATEGORY.......: Server-Sprint TASK ID........: 107 (http://askmonty.org/worklog/?tid=107) VERSION........: Server-9.x STATUS.........: Un-Assigned PRIORITY.......: 60 WORKED HOURS...: 0 ESTIMATE.......: 0 (hours remain) ORIG. ESTIMATE.: 0 PROGRESS NOTES: -=-=(Guest - Mon, 15 Mar 2010, 14:18)=-=- High-Level Specification modified. --- /tmp/wklog.107.old.9086 2010-03-15 14:18:18.000000000 +0000 +++ /tmp/wklog.107.new.9086 2010-03-15 14:18:18.000000000 +0000 @@ -1 +1,43 @@ +Current ideas/status after discussions on the mailing list: + + - Implement a set of plugin APIs and use them to move all of the existing + MySQL replication into a (set of) plugins. + + - Design the APIs so that they can support full MySQL replication, but also + so that they do not hardcode assumptions about how this replication + implementation is done, and so that they will be suitable for other types of + replication (Tungsten, Galera, parallel replication, ...). + + - APIs need to include the concept of a global transaction ID. Need to + determine the extent to which the semantics of such ID will be defined + by the API, and to which extend it will be defined by the plugin + implementations. + + - APIs should properly support reliable crash-recovery with decent + performance (eg. not require multiple mandatory fsync()s per commit, and + not make group commit impossible). + + - Would be nice if the API provided facilities for implementing good + consistency checking support (mainly checking master tables against slave + tables is hard here I think, but also applying wrong binlog data and + individual event checksums). + + +Steps to make this more concrete: + + - Investigate the current MySQL replication, and list all of the places where + a plugin implementation will need to connect/hook into the MySQL server. + * handler::{write,update,delete}_row() + * Statement execution + * Transaction start/commit + * Table open + * Query safe/not/safe for statement based replication + * Statement-based logging details (user variables, random seed, etc.) + * ... + + - Use this list to make an initial sketch of the set of APIs we need. + + - Use the list to determine the feasibility of this project and the level of + detail in the API needed to support a full replication implementation as a + plugin. -=-=(Serg - Mon, 15 Mar 2010, 14:13)=-=- Observers changed: Sergei DESCRIPTION: This is a top-level task for the project of designing a new set of replication APIs for MariaDB. This task is for the initial discussion of what to do and where to focus. The project is started in this email thread: https://lists.launchpad.net/maria-developers/msg01998.html HIGH-LEVEL SPECIFICATION: Current ideas/status after discussions on the mailing list: - Implement a set of plugin APIs and use them to move all of the existing MySQL replication into a (set of) plugins. - Design the APIs so that they can support full MySQL replication, but also so that they do not hardcode assumptions about how this replication implementation is done, and so that they will be suitable for other types of replication (Tungsten, Galera, parallel replication, ...). - APIs need to include the concept of a global transaction ID. Need to determine the extent to which the semantics of such ID will be defined by the API, and to which extend it will be defined by the plugin implementations. - APIs should properly support reliable crash-recovery with decent performance (eg. not require multiple mandatory fsync()s per commit, and not make group commit impossible). - Would be nice if the API provided facilities for implementing good consistency checking support (mainly checking master tables against slave tables is hard here I think, but also applying wrong binlog data and individual event checksums). Steps to make this more concrete: - Investigate the current MySQL replication, and list all of the places where a plugin implementation will need to connect/hook into the MySQL server. * handler::{write,update,delete}_row() * Statement execution * Transaction start/commit * Table open * Query safe/not/safe for statement based replication * Statement-based logging details (user variables, random seed, etc.) * ... - Use this list to make an initial sketch of the set of APIs we need. - Use the list to determine the feasibility of this project and the level of detail in the API needed to support a full replication implementation as a plugin. ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v3.5.9)

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[Maria-developers] Updated (by Guest): New replication APIs (107)
by worklog-noreply＠askmonty.org 15 Mar '10

15 Mar '10

----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: New replication APIs CREATION DATE..: Mon, 15 Mar 2010, 13:55 SUPERVISOR.....: Knielsen IMPLEMENTOR....: Knielsen COPIES TO......: Sergei CATEGORY.......: Server-Sprint TASK ID........: 107 (http://askmonty.org/worklog/?tid=107) VERSION........: Server-9.x STATUS.........: Un-Assigned PRIORITY.......: 60 WORKED HOURS...: 0 ESTIMATE.......: 0 (hours remain) ORIG. ESTIMATE.: 0 PROGRESS NOTES: -=-=(Guest - Mon, 15 Mar 2010, 14:18)=-=- High-Level Specification modified. --- /tmp/wklog.107.old.9086 2010-03-15 14:18:18.000000000 +0000 +++ /tmp/wklog.107.new.9086 2010-03-15 14:18:18.000000000 +0000 @@ -1 +1,43 @@ +Current ideas/status after discussions on the mailing list: + + - Implement a set of plugin APIs and use them to move all of the existing + MySQL replication into a (set of) plugins. + + - Design the APIs so that they can support full MySQL replication, but also + so that they do not hardcode assumptions about how this replication + implementation is done, and so that they will be suitable for other types of + replication (Tungsten, Galera, parallel replication, ...). + + - APIs need to include the concept of a global transaction ID. Need to + determine the extent to which the semantics of such ID will be defined + by the API, and to which extend it will be defined by the plugin + implementations. + + - APIs should properly support reliable crash-recovery with decent + performance (eg. not require multiple mandatory fsync()s per commit, and + not make group commit impossible). + + - Would be nice if the API provided facilities for implementing good + consistency checking support (mainly checking master tables against slave + tables is hard here I think, but also applying wrong binlog data and + individual event checksums). + + +Steps to make this more concrete: + + - Investigate the current MySQL replication, and list all of the places where + a plugin implementation will need to connect/hook into the MySQL server. + * handler::{write,update,delete}_row() + * Statement execution + * Transaction start/commit + * Table open + * Query safe/not/safe for statement based replication + * Statement-based logging details (user variables, random seed, etc.) + * ... + + - Use this list to make an initial sketch of the set of APIs we need. + + - Use the list to determine the feasibility of this project and the level of + detail in the API needed to support a full replication implementation as a + plugin. -=-=(Serg - Mon, 15 Mar 2010, 14:13)=-=- Observers changed: Sergei DESCRIPTION: This is a top-level task for the project of designing a new set of replication APIs for MariaDB. This task is for the initial discussion of what to do and where to focus. The project is started in this email thread: https://lists.launchpad.net/maria-developers/msg01998.html HIGH-LEVEL SPECIFICATION: Current ideas/status after discussions on the mailing list: - Implement a set of plugin APIs and use them to move all of the existing MySQL replication into a (set of) plugins. - Design the APIs so that they can support full MySQL replication, but also so that they do not hardcode assumptions about how this replication implementation is done, and so that they will be suitable for other types of replication (Tungsten, Galera, parallel replication, ...). - APIs need to include the concept of a global transaction ID. Need to determine the extent to which the semantics of such ID will be defined by the API, and to which extend it will be defined by the plugin implementations. - APIs should properly support reliable crash-recovery with decent performance (eg. not require multiple mandatory fsync()s per commit, and not make group commit impossible). - Would be nice if the API provided facilities for implementing good consistency checking support (mainly checking master tables against slave tables is hard here I think, but also applying wrong binlog data and individual event checksums). Steps to make this more concrete: - Investigate the current MySQL replication, and list all of the places where a plugin implementation will need to connect/hook into the MySQL server. * handler::{write,update,delete}_row() * Statement execution * Transaction start/commit * Table open * Query safe/not/safe for statement based replication * Statement-based logging details (user variables, random seed, etc.) * ... - Use this list to make an initial sketch of the set of APIs we need. - Use the list to determine the feasibility of this project and the level of detail in the API needed to support a full replication implementation as a plugin. ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v3.5.9)

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[Maria-developers] Updated (by Serg): New replication APIs (107)
by worklog-noreply＠askmonty.org 15 Mar '10

15 Mar '10

----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: New replication APIs CREATION DATE..: Mon, 15 Mar 2010, 13:55 SUPERVISOR.....: Knielsen IMPLEMENTOR....: Knielsen COPIES TO......: Sergei CATEGORY.......: Server-Sprint TASK ID........: 107 (http://askmonty.org/worklog/?tid=107) VERSION........: Server-9.x STATUS.........: Un-Assigned PRIORITY.......: 60 WORKED HOURS...: 0 ESTIMATE.......: 0 (hours remain) ORIG. ESTIMATE.: 0 PROGRESS NOTES: -=-=(Serg - Mon, 15 Mar 2010, 14:13)=-=- Observers changed: Sergei DESCRIPTION: This is a top-level task for the project of designing a new set of replication APIs for MariaDB. This task is for the initial discussion of what to do and where to focus. The project is started in this email thread: https://lists.launchpad.net/maria-developers/msg01998.html ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v3.5.9)

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[Maria-developers] Updated (by Serg): New replication APIs (107)
by worklog-noreply＠askmonty.org 15 Mar '10

15 Mar '10

----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: New replication APIs CREATION DATE..: Mon, 15 Mar 2010, 13:55 SUPERVISOR.....: Knielsen IMPLEMENTOR....: Knielsen COPIES TO......: Sergei CATEGORY.......: Server-Sprint TASK ID........: 107 (http://askmonty.org/worklog/?tid=107) VERSION........: Server-9.x STATUS.........: Un-Assigned PRIORITY.......: 60 WORKED HOURS...: 0 ESTIMATE.......: 0 (hours remain) ORIG. ESTIMATE.: 0 PROGRESS NOTES: -=-=(Serg - Mon, 15 Mar 2010, 14:13)=-=- Observers changed: Sergei DESCRIPTION: This is a top-level task for the project of designing a new set of replication APIs for MariaDB. This task is for the initial discussion of what to do and where to focus. The project is started in this email thread: https://lists.launchpad.net/maria-developers/msg01998.html ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v3.5.9)

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[Maria-developers] New (by Knielsen): New replication APIs (107)
by worklog-noreply＠askmonty.org 15 Mar '10

15 Mar '10

----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: New replication APIs CREATION DATE..: Mon, 15 Mar 2010, 13:55 SUPERVISOR.....: Knielsen IMPLEMENTOR....: Knielsen COPIES TO......: CATEGORY.......: Server-Sprint TASK ID........: 107 (http://askmonty.org/worklog/?tid=107) VERSION........: Server-9.x STATUS.........: Un-Assigned PRIORITY.......: 60 WORKED HOURS...: 0 ESTIMATE.......: 0 (hours remain) ORIG. ESTIMATE.: 0 PROGRESS NOTES: DESCRIPTION: This is a top-level task for the project of designing a new set of replication APIs for MariaDB. This task is for the initial discussion of what to do and where to focus. The project is started in this email thread: https://lists.launchpad.net/maria-developers/msg01998.html ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v3.5.9)

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[Maria-developers] Rev 2778: Merge in file:///home/psergey/dev/maria-5.3-subqueries-r7-rel/
by Sergey Petrunya 15 Mar '10

15 Mar '10

At file:///home/psergey/dev/maria-5.3-subqueries-r7-rel/ ------------------------------------------------------------ revno: 2778 [merge] revision-id: psergey(a)askmonty.org-20100315063535-jsp4jgya6lfqt8e6 parent: psergey(a)askmonty.org-20100315063254-z1ctm7srl0573s5c parent: psergey(a)askmonty.org-20100315060659-0spqc4jdav12ja2u committer: Sergey Petrunya <psergey(a)askmonty.org> branch nick: maria-5.3-subqueries-r7-rel timestamp: Mon 2010-03-15 09:35:35 +0300 message: Merge modified: mysql-test/r/type_datetime.result sp1f-type_datetime.result-20001228015634-jrgwqpilnfn4kvdp6wm5hp5imvf3tkek === modified file 'mysql-test/r/type_datetime.result' --- a/mysql-test/r/type_datetime.result 2010-02-11 21:59:32 +0000 +++ b/mysql-test/r/type_datetime.result 2010-03-15 06:06:59 +0000 @@ -516,7 +516,7 @@ 1 PRIMARY NULL NULL NULL NULL NULL NULL NULL NULL Impossible WHERE noticed after reading const tables Warnings: Note 1276 Field or reference 'test.t1.cur_date' of SELECT #2 was resolved in SELECT #1 -Note 1003 select '1' AS `id`,'2007-04-25 18:30:22' AS `cur_date` from `test`.`t1` `x1` join `test`.`t1` where (('2007-04-25 18:30:22' = 0)) +Note 1003 select '1' AS `id`,'2007-04-25 18:30:22' AS `cur_date` from `test`.`t1` semi join (`test`.`t1` `x1`) where (('2007-04-25 18:30:22' = 0)) select * from t1 where id in (select id from t1 as x1 where (t1.cur_date is null)); id cur_date @@ -527,7 +527,7 @@ 1 PRIMARY NULL NULL NULL NULL NULL NULL NULL NULL Impossible WHERE noticed after reading const tables Warnings: Note 1276 Field or reference 'test.t2.cur_date' of SELECT #2 was resolved in SELECT #1 -Note 1003 select '1' AS `id`,'2007-04-25' AS `cur_date` from `test`.`t2` `x1` join `test`.`t2` where (('2007-04-25' = 0)) +Note 1003 select '1' AS `id`,'2007-04-25' AS `cur_date` from `test`.`t2` semi join (`test`.`t2` `x1`) where (('2007-04-25' = 0)) select * from t2 where id in (select id from t2 as x1 where (t2.cur_date is null)); id cur_date

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