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BUG#919878: Assertion `!eliminated_tables...

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- In MySQL 5.5, print_join() was re-worked to print "FROM dual" when all
  tables are constant. This change didn't work together with table 
  elimination.
This commit is contained in:
Sergey Petrunya
2012-02-21 01:08:22 +04:00
parent 150f238538
commit 0099593562
3 changed files with 62 additions and 2 deletions
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19
mysql-test/r/table_elim.result
View File

@ -588,4 +588,23 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 eq_ref PRIMARY PRIMARY 4 test.t1.a 1 Using where; Using index
drop view v1;
DROP TABLE t1,t2,t3;
#
# BUG#919878: Assertion `!eliminated_tables...
#
CREATE TABLE t1 ( a INT );
INSERT INTO t1 VALUES (1);
CREATE TABLE t2
( b INT, UNIQUE INDEX(b) );
INSERT INTO t2 VALUES (1),(2);
EXPLAIN EXTENDED
SELECT * FROM t2
WHERE b IN (
SELECT SUM(a) FROM t1 LEFT JOIN t2 ON b=a
);
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t2 index NULL b 5 NULL 2 100.00 Using where; Using index
2 DEPENDENT SUBQUERY t1 system NULL NULL NULL NULL 1 100.00
Warnings:
Note 1003 select `test`.`t2`.`b` AS `b` from `test`.`t2` where <expr_cache><`test`.`t2`.`b`>(<in_optimizer>(`test`.`t2`.`b`,<exists>(select sum(1) from dual where 1 having (<cache>(`test`.`t2`.`b`) = <ref_null_helper>(sum(1))))))
DROP TABLE t1,t2;
SET optimizer_switch=@save_optimizer_switch;

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

@ -521,4 +521,22 @@ EXPLAIN SELECT alias1.* FROM t3 LEFT JOIN v1 as alias1 ON ( t3.a = alias1.b );
drop view v1;
DROP TABLE t1,t2,t3;
--echo #
--echo # BUG#919878: Assertion `!eliminated_tables...
--echo #
CREATE TABLE t1 ( a INT );
INSERT INTO t1 VALUES (1);
CREATE TABLE t2
( b INT, UNIQUE INDEX(b) );
INSERT INTO t2 VALUES (1),(2);
EXPLAIN EXTENDED
SELECT * FROM t2
WHERE b IN (
SELECT SUM(a) FROM t1 LEFT JOIN t2 ON b=a
);
DROP TABLE t1,t2;
SET optimizer_switch=@save_optimizer_switch;

27
sql/sql_select.cc
View File

@ -21442,6 +21442,8 @@ static void print_table_array(THD *thd,
(curr->nested_join && !(curr->nested_join->used_tables &
~eliminated_tables))))
{
/* as of 5.5, print_join doesnt put eliminated elements into array */
DBUG_ASSERT(0);
continue;
}
@ -21467,6 +21469,21 @@ static void print_table_array(THD *thd,
}
/*
Check if the passed table is
- a base table which was eliminated, or
- a join nest which only contained eliminated tables (and so was eliminated,
too)
*/
static bool is_eliminated_table(table_map eliminated_tables, TABLE_LIST *tbl)
{
return eliminated_tables &&
((tbl->table && (tbl->table->map & eliminated_tables)) ||
(tbl->nested_join && !(tbl->nested_join->used_tables &
~eliminated_tables)));
}
/**
Print joins from the FROM clause.
@ -21488,8 +21505,14 @@ static void print_join(THD *thd,
uint non_const_tables= 0;
for (TABLE_LIST *t= ti++; t ; t= ti++)
if (!t->optimized_away)
{
/*
See comment in print_table_array() about the second part of the
condition
*/
if (!t->optimized_away && !is_eliminated_table(eliminated_tables, t))
non_const_tables++;
}
if (!non_const_tables)
{
str->append(STRING_WITH_LEN("dual"));
@ -21504,7 +21527,7 @@ static void print_join(THD *thd,
TABLE_LIST *tmp, **t= table + (non_const_tables - 1);
while ((tmp= ti++))
{
if (tmp->optimized_away)
if (tmp->optimized_away || is_eliminated_table(eliminated_tables, tmp))
continue;
*t--= tmp;
}