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MDEV-327: SHOW EXPLAIN: Different select_type in plans produced by SHOW EXPLAIN and EXPLAIN

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- SHOW EXPLAIN actually produced correct plan
- Apply fix for lp:1013343 to make EXPLAIN and SHOW EXPLAIN uniform.
This commit is contained in:
Sergey Petrunya 2012-06-19 13:53:16 +04:00
parent fb33db5608
commit 1ce0c706b3
3 changed files with 72 additions and 1 deletions
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36
mysql-test/r/show_explain.result
View file

@ -659,4 +659,40 @@ Note 1003 SELECT a FROM t1 WHERE a IN ( SELECT 1+SLEEP(0.01) UNION SELECT 2 )
a
set debug_dbug='';
DROP TABLE t1;
#
# MDEV-327: SHOW EXPLAIN: Different select_type in plans produced by SHOW EXPLAIN
# and standard EXPLAIN: 'SUBQUERY' vs 'DEPENDENT SUBQUERY'
#
CREATE TABLE t1 (a INT) ENGINE=Aria;
INSERT INTO t1 VALUES
(4),(6),(3),(5),(3),(246),(2),(9),(3),(8),
(1),(8),(8),(5),(7),(5),(1),(6),(2),(9);
CREATE TABLE t2 (b INT) ENGINE=Aria;
INSERT INTO t2 VALUES
(1),(7),(4),(7),(0),(2),(9),(4),(0),(9),
(1),(3),(8),(8),(18),(84),(6),(3),(6),(6);
EXPLAIN
SELECT * FROM t1, ( SELECT * FROM t2 ) AS alias
WHERE a < ALL ( SELECT b FROM t1, t2 WHERE a = b );
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 20 Using where
1 PRIMARY t2 ALL NULL NULL NULL NULL 20
3 SUBQUERY t1 ALL NULL NULL NULL NULL 20
3 SUBQUERY t2 ALL NULL NULL NULL NULL 20 Using where
set @show_explain_probe_select_id=1;
set debug_dbug='d,show_explain_probe_join_exec_start';
SELECT * FROM t1, ( SELECT * FROM t2 ) AS alias
WHERE a < ALL ( SELECT b FROM t1, t2 WHERE a = b );
show explain for $thr2;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 20 Using where
1 PRIMARY t2 ALL NULL NULL NULL NULL 20
3 SUBQUERY t1 ALL NULL NULL NULL NULL 20
3 SUBQUERY t2 ALL NULL NULL NULL NULL 20 Using where
Warnings:
Note 1003 SELECT * FROM t1, ( SELECT * FROM t2 ) AS alias
WHERE a < ALL ( SELECT b FROM t1, t2 WHERE a = b )
a b
set debug_dbug='';
DROP TABLE t1, t2;
drop table t0;

35
mysql-test/t/show_explain.test
View file

@ -662,6 +662,41 @@ set debug_dbug='';
DROP TABLE t1;
--echo #
--echo # MDEV-327: SHOW EXPLAIN: Different select_type in plans produced by SHOW EXPLAIN
--echo # and standard EXPLAIN: 'SUBQUERY' vs 'DEPENDENT SUBQUERY'
--echo #
CREATE TABLE t1 (a INT) ENGINE=Aria;
INSERT INTO t1 VALUES
(4),(6),(3),(5),(3),(246),(2),(9),(3),(8),
(1),(8),(8),(5),(7),(5),(1),(6),(2),(9);
CREATE TABLE t2 (b INT) ENGINE=Aria;
INSERT INTO t2 VALUES
(1),(7),(4),(7),(0),(2),(9),(4),(0),(9),
(1),(3),(8),(8),(18),(84),(6),(3),(6),(6);
EXPLAIN
SELECT * FROM t1, ( SELECT * FROM t2 ) AS alias
WHERE a < ALL ( SELECT b FROM t1, t2 WHERE a = b );
set @show_explain_probe_select_id=1;
set debug_dbug='d,show_explain_probe_join_exec_start';
--send
SELECT * FROM t1, ( SELECT * FROM t2 ) AS alias
WHERE a < ALL ( SELECT b FROM t1, t2 WHERE a = b );
connection default;
--source include/wait_condition.inc
evalp show explain for $thr2;
connection con1;
reap;
set debug_dbug='';
DROP TABLE t1, t2;
## TODO: Test this: have several SHOW EXPLAIN requests be queued up for a
## thread and served together.

2
sql/item_subselect.cc
View file

@ -1813,7 +1813,7 @@ bool Item_allany_subselect::is_maxmin_applicable(JOIN *join)
WHERE condition.
*/
return (abort_on_null || (upper_item && upper_item->is_top_level_item())) &&
!join->select_lex->master_unit()->uncacheable && !func->eqne_op();
!(join->select_lex->master_unit()->uncacheable & ~UNCACHEABLE_EXPLAIN) && !func->eqne_op();
}