Hello Igor, On Thu, Nov 18, 2010 at 10:04:24PM -0800, Igor Babaev wrote:

Sergey,

Please review this fix.

Ok to push after the irc feedback (lack of comments about JOIN_CACHE format) is addressed.

-------- Original Message -------- Subject: [Commits] Rev 2860: Fixed LP bug #675922. in file:///home/igor/maria/maria-5.3-mwl128-bug675922/ Date: Thu, 18 Nov 2010 22:02:41 -0800 (PST) From: Igor Babaev <igor@askmonty.org> Reply-To: maria-developers@lists.launchpad.net To: <commits@mariadb.org>

At file:///home/igor/maria/maria-5.3-mwl128-bug675922/

------------------------------------------------------------ revno: 2860 revision-id: igor@askmonty.org-20101119060240-gzh1k5gxl3aazk45 parent: igor@askmonty.org-20101118221357-zg55d3erru07ugzy committer: Igor Babaev <igor@askmonty.org> branch nick: maria-5.3-mwl128-bug675922 timestamp: Thu 2010-11-18 22:02:40 -0800 message: Fixed LP bug #675922. The bug happened when BKA join algorithm used an incremental buffer and some of the fields over which access keys were constructed - were allocated in the previous join buffers - were non-nullable - belonged to inner tables of outer joins. For such fields an offset to the field value in the record is saved in the postfix of the record, and a zero offset indicates that the value is null. Before the key using the field value is constructed the value is read into the corresponding field of the record buffer and the null bit is set for the field if the offset is 0. However if the field is non-nullable the table->null_row must be set to 1 for null values and to 0 for non-null values to ensure proper reading of the value from the record buffer.

=== modified file 'mysql-test/r/join_cache.result' --- a/mysql-test/r/join_cache.result 2010-11-18 22:13:57 +0000 +++ b/mysql-test/r/join_cache.result 2010-11-19 06:02:40 +0000 @@ -6004,4 +6004,56 @@ SET SESSION optimizer_switch = 'outer_join_with_cache=off'; SET SESSION join_cache_level = DEFAULT; DROP TABLE t1,t2,t3; +# +# Bug #675922: incremental buffer for BKA with access from previous +# buffers from non-nullable columns whose values may be null +# +CREATE TABLE t1 (a1 varchar(32)) ; +INSERT INTO t1 VALUES ('s'),('k'); +CREATE TABLE t2 (a2 int PRIMARY KEY, b2 varchar(32)) ; +INSERT INTO t2 VALUES (7,'s'); +CREATE TABLE t3 (a3 int PRIMARY KEY, b3 varchar(32)) ; +INSERT INTO t3 VALUES (7,'s'); +CREATE TABLE t4 (a4 int) ; +INSERT INTO t4 VALUES (9); +CREATE TABLE t5(a5 int PRIMARY KEY, b5 int) ; +INSERT INTO t5 VALUES (7,0); +SET SESSION optimizer_switch = 'outer_join_with_cache=on'; +SET SESSION join_cache_level = 0; +EXPLAIN +SELECT t4.a4, t5.b5 +FROM ((t1 LEFT JOIN (t2 JOIN t3 ON t2.a2 = t3.a3) ON t2.b2 = t1.a1) +LEFT JOIN t4 ON t4.a4 <> 0) LEFT JOIN t5 ON t5.a5 = t2.a2; +id select_type table type possible_keys key key_len ref rows Extra +1 SIMPLE t1 ALL NULL NULL NULL NULL 2 +1 SIMPLE t2 ALL PRIMARY NULL NULL NULL 1 Using where +1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t2.a2 1 Using index +1 SIMPLE t4 ALL NULL NULL NULL NULL 1 Using where +1 SIMPLE t5 eq_ref PRIMARY PRIMARY 4 test.t2.a2 1 Using where +SELECT t4.a4, t5.b5 +FROM ((t1 LEFT JOIN (t2 JOIN t3 ON t2.a2 = t3.a3) ON t2.b2 = t1.a1) +LEFT JOIN t4 ON t4.a4 <> 0) LEFT JOIN t5 ON t5.a5 = t2.a2; +a4 b5 +9 0 +9 NULL +SET SESSION join_cache_level = 6; +EXPLAIN +SELECT t4.a4, t5.b5 +FROM ((t1 LEFT JOIN (t2 JOIN t3 ON t2.a2 = t3.a3) ON t2.b2 = t1.a1) +LEFT JOIN t4 ON t4.a4 <> 0) LEFT JOIN t5 ON t5.a5 = t2.a2; +id select_type table type possible_keys key key_len ref rows Extra +1 SIMPLE t1 ALL NULL NULL NULL NULL 2 +1 SIMPLE t2 ALL PRIMARY NULL NULL NULL 1 Using where +1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t2.a2 1 Using index +1 SIMPLE t4 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (flat, BNL join) +1 SIMPLE t5 eq_ref PRIMARY PRIMARY 4 test.t2.a2 1 Using where; Using join buffer (incremental, BKA join) +SELECT t4.a4, t5.b5 +FROM ((t1 LEFT JOIN (t2 JOIN t3 ON t2.a2 = t3.a3) ON t2.b2 = t1.a1) +LEFT JOIN t4 ON t4.a4 <> 0) LEFT JOIN t5 ON t5.a5 = t2.a2; +a4 b5 +9 0 +9 NULL +SET SESSION optimizer_switch = 'outer_join_with_cache=off'; +SET SESSION join_cache_level = DEFAULT; +DROP TABLE t1,t2,t3,t4,t5; set @@optimizer_switch=@save_optimizer_switch;

=== modified file 'mysql-test/t/join_cache.test' --- a/mysql-test/t/join_cache.test 2010-11-18 22:13:57 +0000 +++ b/mysql-test/t/join_cache.test 2010-11-19 06:02:40 +0000 @@ -2655,5 +2655,50 @@

DROP TABLE t1,t2,t3;

+--echo # +--echo # Bug #675922: incremental buffer for BKA with access from previous +--echo # buffers from non-nullable columns whose values may be null +--echo # + +CREATE TABLE t1 (a1 varchar(32)) ; +INSERT INTO t1 VALUES ('s'),('k'); + +CREATE TABLE t2 (a2 int PRIMARY KEY, b2 varchar(32)) ; +INSERT INTO t2 VALUES (7,'s'); + +CREATE TABLE t3 (a3 int PRIMARY KEY, b3 varchar(32)) ; +INSERT INTO t3 VALUES (7,'s'); + +CREATE TABLE t4 (a4 int) ; +INSERT INTO t4 VALUES (9); + +CREATE TABLE t5(a5 int PRIMARY KEY, b5 int) ; +INSERT INTO t5 VALUES (7,0); + +SET SESSION optimizer_switch = 'outer_join_with_cache=on'; + +SET SESSION join_cache_level = 0; +EXPLAIN +SELECT t4.a4, t5.b5 + FROM ((t1 LEFT JOIN (t2 JOIN t3 ON t2.a2 = t3.a3) ON t2.b2 = t1.a1) + LEFT JOIN t4 ON t4.a4 <> 0) LEFT JOIN t5 ON t5.a5 = t2.a2; +SELECT t4.a4, t5.b5 + FROM ((t1 LEFT JOIN (t2 JOIN t3 ON t2.a2 = t3.a3) ON t2.b2 = t1.a1) + LEFT JOIN t4 ON t4.a4 <> 0) LEFT JOIN t5 ON t5.a5 = t2.a2; + +SET SESSION join_cache_level = 6; +EXPLAIN +SELECT t4.a4, t5.b5 + FROM ((t1 LEFT JOIN (t2 JOIN t3 ON t2.a2 = t3.a3) ON t2.b2 = t1.a1) + LEFT JOIN t4 ON t4.a4 <> 0) LEFT JOIN t5 ON t5.a5 = t2.a2; +SELECT t4.a4, t5.b5 + FROM ((t1 LEFT JOIN (t2 JOIN t3 ON t2.a2 = t3.a3) ON t2.b2 = t1.a1) + LEFT JOIN t4 ON t4.a4 <> 0) LEFT JOIN t5 ON t5.a5 = t2.a2; + +SET SESSION optimizer_switch = 'outer_join_with_cache=off'; +SET SESSION join_cache_level = DEFAULT; + +DROP TABLE t1,t2,t3,t4,t5; + # this must be the last command in the file set @@optimizer_switch=@save_optimizer_switch;

=== modified file 'sql/sql_join_cache.cc' --- a/sql/sql_join_cache.cc 2010-11-13 15:47:43 +0000 +++ b/sql/sql_join_cache.cc 2010-11-19 06:02:40 +0000 @@ -1805,14 +1805,21 @@ size_of_fld_ofs* (referenced_fields+1-copy->referenced_field_no)); bool is_null= FALSE; + Field *field= copy->field; if (offset == 0 && flag_fields) is_null= TRUE; if (is_null) - copy->field->set_null(); + { + field->set_null(); + if (!field->real_maybe_null()) + field->table->null_row= 1; + } else { uchar *save_pos= pos; - copy->field->set_notnull(); + field->set_notnull(); + if (!field->real_maybe_null()) + field->table->null_row= 0; pos= rec_ptr+offset; read_record_field(copy, blob_data_is_in_rec_buff(rec_ptr)); pos= save_pos;

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-- BR Sergey -- Sergey Petrunia, Software Developer Monty Program AB, http://askmonty.org Blog: http://s.petrunia.net/blog