From bd39e4ba2e7fb34e00027e0f1e9a2b048d1ce5c2 Mon Sep 17 00:00:00 2001 From: unknown <igor@olga.mysql.com> Date: Sun, 11 Mar 2007 23:34:40 -0700 Subject: [PATCH] Fixed bug #26963: invalid optimization of the pushdown conditions after single-row table substitution could lead to a wrong result set. The bug happened because the function Item_field::replace_equal_field erroniously assumed that any field included in a multiple equality with a constant has been already substituted for this constant. This not true for fields becoming constant after row substitutions for constant tables. mysql-test/r/select.result: Added a test case for bug #26963. mysql-test/t/select.test: Added a test case for bug #26963. sql/item.cc: Fixed bug #26963: invalid optimization of the pushdown conditions after single-row table substitution could lead to a wrong result set. The bug happened because the function Item_field::replace_equal_field erroneously assumed that any field included in a multiple equality with a constant has been already substituted for this constant. This not true for fields becoming constant after row substitutions for constant tables. --- mysql-test/r/select.result | 38 ++++++++++++++++++++++++++++++ mysql-test/t/select.test | 47 ++++++++++++++++++++++++++++++++++++++ sql/item.cc | 15 ++++++++++-- 3 files changed, 98 insertions(+), 2 deletions(-) diff --git a/mysql-test/r/select.result b/mysql-test/r/select.result index c3132a1b5f6..ae32607973a 100644 --- a/mysql-test/r/select.result +++ b/mysql-test/r/select.result @@ -3933,4 +3933,42 @@ cc cc 7 aa aa 2 aa aa 2 DROP TABLE t1,t2; +CREATE TABLE t1 ( +access_id int NOT NULL default '0', +name varchar(20) default NULL, +rank int NOT NULL default '0', +KEY idx (access_id) +); +CREATE TABLE t2 ( +faq_group_id int NOT NULL default '0', +faq_id int NOT NULL default '0', +access_id int default NULL, +UNIQUE KEY idx1 (faq_id), +KEY idx2 (faq_group_id,faq_id) +); +INSERT INTO t1 VALUES +(1,'Everyone',2),(2,'Help',3),(3,'Technical Support',1),(4,'Chat User',4); +INSERT INTO t2 VALUES +(261,265,1),(490,494,1); +SELECT t2.faq_id +FROM t1 INNER JOIN t2 IGNORE INDEX (idx1) +ON (t1.access_id = t2.access_id) +LEFT JOIN t2 t +ON (t.faq_group_id = t2.faq_group_id AND +find_in_set(t.access_id, '1,4') < find_in_set(t2.access_id, '1,4')) +WHERE +t2.access_id IN (1,4) AND t.access_id IS NULL AND t2.faq_id in (265); +faq_id +265 +SELECT t2.faq_id +FROM t1 INNER JOIN t2 +ON (t1.access_id = t2.access_id) +LEFT JOIN t2 t +ON (t.faq_group_id = t2.faq_group_id AND +find_in_set(t.access_id, '1,4') < find_in_set(t2.access_id, '1,4')) +WHERE +t2.access_id IN (1,4) AND t.access_id IS NULL AND t2.faq_id in (265); +faq_id +265 +DROP TABLE t1,t2; End of 5.0 tests diff --git a/mysql-test/t/select.test b/mysql-test/t/select.test index ea5fadb2e1b..8442a073620 100644 --- a/mysql-test/t/select.test +++ b/mysql-test/t/select.test @@ -3299,4 +3299,51 @@ SELECT * FROM t1 LEFT JOIN t2 ON t1.name=t2.name; DROP TABLE t1,t2; + +# +# Bug #26963: join with predicates that contain fields from equalities evaluated +# to constants after constant table substitution +# + +CREATE TABLE t1 ( + access_id int NOT NULL default '0', + name varchar(20) default NULL, + rank int NOT NULL default '0', + KEY idx (access_id) +); + +CREATE TABLE t2 ( + faq_group_id int NOT NULL default '0', + faq_id int NOT NULL default '0', + access_id int default NULL, + UNIQUE KEY idx1 (faq_id), + KEY idx2 (faq_group_id,faq_id) +); + +INSERT INTO t1 VALUES + (1,'Everyone',2),(2,'Help',3),(3,'Technical Support',1),(4,'Chat User',4); +INSERT INTO t2 VALUES + (261,265,1),(490,494,1); + + +SELECT t2.faq_id + FROM t1 INNER JOIN t2 IGNORE INDEX (idx1) + ON (t1.access_id = t2.access_id) + LEFT JOIN t2 t + ON (t.faq_group_id = t2.faq_group_id AND + find_in_set(t.access_id, '1,4') < find_in_set(t2.access_id, '1,4')) + WHERE + t2.access_id IN (1,4) AND t.access_id IS NULL AND t2.faq_id in (265); + +SELECT t2.faq_id + FROM t1 INNER JOIN t2 + ON (t1.access_id = t2.access_id) + LEFT JOIN t2 t + ON (t.faq_group_id = t2.faq_group_id AND + find_in_set(t.access_id, '1,4') < find_in_set(t2.access_id, '1,4')) + WHERE + t2.access_id IN (1,4) AND t.access_id IS NULL AND t2.faq_id in (265); + +DROP TABLE t1,t2; + --echo End of 5.0 tests diff --git a/sql/item.cc b/sql/item.cc index ec33bf1ddc7..11a5039ca19 100644 --- a/sql/item.cc +++ b/sql/item.cc @@ -4075,7 +4075,9 @@ bool Item_field::set_no_const_sub(byte *arg) DESCRIPTION The function returns a pointer to an item that is taken from the very beginning of the item_equal list which the Item_field - object refers to (belongs to). + object refers to (belongs to) unless item_equal contains a constant + item. In this case the function returns this constant item, + (if the substitution does not require conversion). If the Item_field object does not refer any Item_equal object 'this' is returned @@ -4084,7 +4086,8 @@ bool Item_field::set_no_const_sub(byte *arg) of the thransformer method. RETURN VALUES - pointer to a replacement Item_field if there is a better equal item; + pointer to a replacement Item_field if there is a better equal item or + a pointer to a constant equal item; this - otherwise. */ @@ -4092,6 +4095,14 @@ Item *Item_field::replace_equal_field(byte *arg) { if (item_equal) { + Item *const_item= item_equal->get_const(); + if (const_item) + { + if (cmp_context != (Item_result)-1 && + const_item->cmp_context != cmp_context) + return this; + return const_item; + } Item_field *subst= item_equal->get_first(); if (subst && !field->eq(subst->field)) return subst; -- 2.30.9