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BUG#884184: Wrong result with RIGHT JOIN + derived_merge

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- Make eliminate_tables_for_list() take into account that it is not possible
  to eliminate a table if it is used in the upper-side ON expressions. Example:

    xxx JOIN (t1 LEFT JOIN t2 ON cond ) ON func(t2.columns)

  Here it would eliminate t2 which is not possible because of use of t2.columns.
This commit is contained in:
Sergey Petrunya 2011-11-01 12:36:43 +04:00
parent aa327cdd48
commit f2b6f4e3df
3 changed files with 39 additions and 0 deletions
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19
mysql-test/r/table_elim.result
View File

@ -566,3 +566,22 @@ id select_type table type possible_keys key key_len ref rows Extra
# ^^ The above must not produce a QEP of t3,t5,t2,t4
# as that violates the "no interleaving of outer join nests" rule.
DROP TABLE t1,t2,t3,t4,t5;
#
# BUG#884184: Wrong result with RIGHT JOIN + derived_merge
#
CREATE TABLE t1 (a int(11), b varchar(1)) ;
INSERT IGNORE INTO t1 VALUES (0,'g');
CREATE TABLE t3 ( a varchar(1)) ;
INSERT IGNORE INTO t3 VALUES ('g');
CREATE TABLE t2 ( a int(11) NOT NULL, PRIMARY KEY (a)) ;
create view v1 as SELECT t1.* FROM t1 LEFT JOIN t2 ON ( t1.a = t2.a ) WHERE t2.a <> 0;
SELECT alias1.* FROM t3 LEFT JOIN v1 as alias1 ON ( t3.a = alias1.b );
a b
NULL NULL
EXPLAIN SELECT alias1.* FROM t3 LEFT JOIN v1 as alias1 ON ( t3.a = alias1.b );
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t3 system NULL NULL NULL NULL 1
1 SIMPLE t1 ALL NULL NULL NULL NULL 1
1 SIMPLE t2 eq_ref PRIMARY PRIMARY 4 test.t1.a 1 Using index
drop view v1;
DROP TABLE t1,t2,t3;

18
mysql-test/t/table_elim.test
View File

@ -499,3 +499,21 @@ WHERE t3.f2 ;
DROP TABLE t1,t2,t3,t4,t5;
--echo #
--echo # BUG#884184: Wrong result with RIGHT JOIN + derived_merge
--echo #
CREATE TABLE t1 (a int(11), b varchar(1)) ;
INSERT IGNORE INTO t1 VALUES (0,'g');
CREATE TABLE t3 ( a varchar(1)) ;
INSERT IGNORE INTO t3 VALUES ('g');
CREATE TABLE t2 ( a int(11) NOT NULL, PRIMARY KEY (a)) ;
create view v1 as SELECT t1.* FROM t1 LEFT JOIN t2 ON ( t1.a = t2.a ) WHERE t2.a <> 0;
SELECT alias1.* FROM t3 LEFT JOIN v1 as alias1 ON ( t3.a = alias1.b );
EXPLAIN SELECT alias1.* FROM t3 LEFT JOIN v1 as alias1 ON ( t3.a = alias1.b );
drop view v1;
DROP TABLE t1,t2,t3;

2
sql/opt_table_elimination.cc
View File

@ -695,6 +695,8 @@ eliminate_tables_for_list(JOIN *join, List<TABLE_LIST> *join_list,
{
table_map outside_used_tables= tables_used_elsewhere |
tables_used_on_left;
if (on_expr)
outside_used_tables |= on_expr->used_tables();
if (tbl->nested_join)
{
/* This is "... LEFT JOIN (join_nest) ON cond" */