Hi Sanja, The patch doesn't take one thing into account. Consider a query: explain select * from t12 where b>3 or exists (select max(t10.b) Z from t10 where t10.a in ( select t11.a from t11) group by t10.c having Z<100); +--+------------+-----------+------+-------------+------------+-------+----+----+-------------------------------+ |id|select_type |table |type |possible_keys|key |key_len|ref |rows|Extra | +--+------------+-----------+------+-------------+------------+-------+----+----+-------------------------------+ |1 |PRIMARY |t12 |ALL |NULL |NULL |NULL |NULL|10 | | |2 |SUBQUERY |t10 |ALL |NULL |NULL |NULL |NULL|6 |Using temporary; Using filesort| |2 |SUBQUERY |<subquery3>|eq_ref|distinct_key |distinct_key|4 |func|1 | | |3 |MATERIALIZED|t11 |ALL |NULL |NULL |NULL |NULL|6 | | +--+------------+-----------+------+-------------+------------+-------+----+----+-------------------------------+ Here, the EXISTS subquery is the one that will have the problem. I have added "in ( select t11.a from t11)" so that EXISTS subquery's join_tab array is not linear. The problem is not visible to the user, but it can be seen in debugger. Put a breakpoint in JOIN::cleanup(), with these commands: p table->alias->Ptr p table->file Run the query and you'll see: Breakpoint 5, st_join_table::cleanup (this=0x7fff280dbea0) at /home/psergey/dev2/5.5/sql/sql_select.cc:10248 $30 = 0x7fff28000af0 "t12" $31 = (ha_innobase *) 0x7fff28047198 ... Breakpoint 5, st_join_table::cleanup (this=0x7fff28053078) at /home/psergey/dev2/5.5/sql/sql_select.cc:10248 $32 = 0xd05418 "" $33 = (ha_heap *) 0x7fff2805ab98 ... Breakpoint 5, st_join_table::cleanup (this=0x7fff28051ef8) at /home/psergey/dev2/5.5/sql/sql_select.cc:10248 $36 = 0x7fff28025720 "t10" $37 = (ha_innobase *) 0x7fff28009558 ... Breakpoint 5, st_join_table::cleanup (this=0x7fff28052218) at /home/psergey/dev2/5.5/sql/sql_select.cc:10248 $38 = 0xd30a69 "sj-materialize" $39 = (ha_heap *) 0x7fff28054398 ... Note that in subquery join_tab->cleanup() was called for t10, and for sj-materialize. For t11 (which is inside the sj-materialize) it was not called. This caused by this loop being flat loop:
@@ -10646,6 +10646,12 @@ void JOIN::cleanup(bool full) { tab->cleanup(); } + if (join_tab != table_access_tabs) + { + for (uint i= 0; i < top_table_access_tabs_count; i++)a ^^^^^^^^^^^ here. + table_access_tabs[i].cleanup(); + table_access_tabs= join_tab; // avoid second cleanup() + } cleaned= true; } else
It turns out, I was incorrect with the statement that "table_access_tabs array is always flat". On Tue, May 21, 2013 at 08:30:35AM +0300, sanja@montyprogram.com wrote:
At file:///home/bell/maria/bzr/work-maria-5.5-MDEV-4536/
------------------------------------------------------------ revno: 3770 revision-id: sanja@montyprogram.com-20130521053031-xe34093yhvey0l5o parent: monty@askmonty.org-20130515132812-pnjhza9iugz89356 committer: sanja@montyprogram.com branch nick: work-maria-5.5-MDEV-4536 timestamp: Tue 2013-05-21 08:30:31 +0300 message: MDEV-4042 & MDEV-4536 fix.
Optimization JOIN tabs also should be cleaned up (in case of EXPLAIN when we cleaning up everythibng at the end of execution).
=== added file 'mysql-test/r/innodb_explain.result' --- a/mysql-test/r/innodb_explain.result 1970-01-01 00:00:00 +0000 +++ b/mysql-test/r/innodb_explain.result 2013-05-21 05:30:31 +0000 @@ -0,0 +1,34 @@ +drop table if exists t1,t2,t3; +# +# MDEV-4536: sql_base.cc:1598: bool close_thread_table(THD*, TABLE**): +# Assertion `table->key_read == 0' failed. +# +set optimizer_switch="index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_merge_sort_intersection=off,engine_condition_pushdown=off,index_condition_pushdown=on,derived_merge=on,derived_with_keys=on,firstmatch=on,loosescan=on,materialization=on,in_to_exists=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on,subquery_cache=on,mrr=off,mrr_cost_based=off,mrr_sort_keys=off,outer_join_with_cache=on,semijoin_with_cache=on,join_cache_incremental=on,join_cache_hashed=on,join_cache_bka=on,optimize_join_buffer_size=off,table_elimination=on,extended_keys=off"; +CREATE TABLE t1 (pk int auto_increment primary key, `col_int_key` int(11), +key `col_int_key` (`col_int_key`),`col_varchar_key` varchar(128), key +(col_varchar_key)) engine=innodb; +EXPLAIN SELECT 1 FROM t1 AS alias1 WHERE EXISTS ( SELECT SQ2_alias1 . col_int_key AS SQ2_field1 FROM ( t1 AS SQ2_alias1 RIGHT OUTER JOIN t1 AS SQ2_alias2 ON (SQ2_alias2 . col_int_key = SQ2_alias1 . col_int_key ) ) GROUP BY SQ2_field1 HAVING SQ2_alias1 . col_int_key >= 7 ); +id select_type table type possible_keys key key_len ref rows Extra +1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE +2 SUBQUERY SQ2_alias2 index NULL col_int_key 5 NULL 1 Using index; Using temporary; Using filesort +2 SUBQUERY SQ2_alias1 ref col_int_key col_int_key 5 test.SQ2_alias2.col_int_key 1 Using where; Using index +set optimizer_switch=default; +drop table t1; +# +# MDEV-4042: Assertion `table->key_read == 0' fails in +# close_thread_table on EXPLAIN with GROUP BY and HAVING in +# EXISTS SQ, InnoDB +# +CREATE TABLE t1 (a INT) ENGINE=InnoDB; +CREATE TABLE t2 (b INT PRIMARY KEY, c INT) ENGINE=InnoDB; +CREATE TABLE t3 (d INT) ENGINE=InnoDB; +EXPLAIN +SELECT * FROM t1 +WHERE EXISTS ( SELECT b FROM t2, t3 +GROUP BY b +HAVING b != 3 ); +id select_type table type possible_keys key key_len ref rows Extra +1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE +2 SUBQUERY t2 index NULL PRIMARY 4 NULL 1 Using index; Using temporary; Using filesort +2 SUBQUERY t3 ALL NULL NULL NULL NULL 1 Using join buffer (flat, BNL join) +drop table t1,t2,t3;
=== added file 'mysql-test/t/innodb_explain.test' --- a/mysql-test/t/innodb_explain.test 1970-01-01 00:00:00 +0000 +++ b/mysql-test/t/innodb_explain.test 2013-05-21 05:30:31 +0000 @@ -0,0 +1,41 @@ +# +# Innodb specific explains + +--disable_warnings +drop table if exists t1,t2,t3; +--enable_warnings + +--source include/have_innodb.inc + +--echo # +--echo # MDEV-4536: sql_base.cc:1598: bool close_thread_table(THD*, TABLE**): +--echo # Assertion `table->key_read == 0' failed. +--echo # +set optimizer_switch="index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_merge_sort_intersection=off,engine_condition_pushdown=off,index_condition_pushdown=on,derived_merge=on,derived_with_keys=on,firstmatch=on,loosescan=on,materialization=on,in_to_exists=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on,subquery_cache=on,mrr=off,mrr_cost_based=off,mrr_sort_keys=off,outer_join_with_cache=on,semijoin_with_cache=on,join_cache_incremental=on,join_cache_hashed=on,join_cache_bka=on,optimize_join_buffer_size=off,table_elimination=on,extended_keys=off"; + +CREATE TABLE t1 (pk int auto_increment primary key, `col_int_key` int(11), +key `col_int_key` (`col_int_key`),`col_varchar_key` varchar(128), key +(col_varchar_key)) engine=innodb; + +EXPLAIN SELECT 1 FROM t1 AS alias1 WHERE EXISTS ( SELECT SQ2_alias1 . col_int_key AS SQ2_field1 FROM ( t1 AS SQ2_alias1 RIGHT OUTER JOIN t1 AS SQ2_alias2 ON (SQ2_alias2 . col_int_key = SQ2_alias1 . col_int_key ) ) GROUP BY SQ2_field1 HAVING SQ2_alias1 . col_int_key >= 7 ); + + +set optimizer_switch=default; +drop table t1; + +--echo # +--echo # MDEV-4042: Assertion `table->key_read == 0' fails in +--echo # close_thread_table on EXPLAIN with GROUP BY and HAVING in +--echo # EXISTS SQ, InnoDB +--echo # +CREATE TABLE t1 (a INT) ENGINE=InnoDB; +CREATE TABLE t2 (b INT PRIMARY KEY, c INT) ENGINE=InnoDB; +CREATE TABLE t3 (d INT) ENGINE=InnoDB; + +EXPLAIN +SELECT * FROM t1 +WHERE EXISTS ( SELECT b FROM t2, t3 +GROUP BY b +HAVING b != 3 ); + +drop table t1,t2,t3;
=== modified file 'sql/sql_select.cc' --- a/sql/sql_select.cc 2013-05-07 11:05:09 +0000 +++ b/sql/sql_select.cc 2013-05-21 05:30:31 +0000 @@ -3680,8 +3680,8 @@ make_join_statistics(JOIN *join, List<TA if (pull_out_semijoin_tables(join)) DBUG_RETURN(TRUE);
- join->join_tab=stat; - join->top_join_tab_count= table_count; + join->table_access_tabs= join->join_tab=stat; + join->top_table_access_tabs_count= join->top_join_tab_count= table_count; join->map2table=stat_ref; join->table= table_vector; join->const_tables=const_count; @@ -10646,6 +10646,12 @@ void JOIN::cleanup(bool full) { tab->cleanup(); } + if (join_tab != table_access_tabs) + { + for (uint i= 0; i < top_table_access_tabs_count; i++) + table_access_tabs[i].cleanup(); + table_access_tabs= join_tab; // avoid second cleanup() + } cleaned= true; } else
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-- BR Sergei -- Sergei Petrunia, Software Developer Monty Program AB, http://askmonty.org Blog: http://s.petrunia.net/blog