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MDEV-411: (different results for EXPLAIN and SHOW EXPLAIN)

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- Added a testcase
This commit is contained in:
Sergey Petrunya 2013-10-04 19:09:39 +04:00
parent 5e4044e92c
commit f5fba6564b
2 changed files with 75 additions and 1 deletions
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39
mysql-test/r/show_explain.result
View File

@ -1130,6 +1130,45 @@ set names default;
# #
show explain for foo; show explain for foo;
ERROR HY000: You may only use constant expressions in this statement ERROR HY000: You may only use constant expressions in this statement
#
# MDEV-411: SHOW EXPLAIN: For dependent subquery EXPLAIN produces type=index, key, 'Using where; Using index',
# while SHOW EXPLAIN says type=ALL, no key, 'Range checked for each record'
#
CREATE TABLE t1 (a INT NOT NULL, KEY(a)) ENGINE=MyISAM;
INSERT INTO t1 VALUES (7),(0);
CREATE TABLE t2 (b INT NOT NULL) ENGINE=MyISAM;
INSERT INTO t2 VALUES (0),(8);
explain
SELECT SUM(b) FROM ( SELECT * FROM t1 ) AS alias1, t2
WHERE b <= ANY (
SELECT a FROM t1
WHERE a = b + SLEEP(0.2) OR a >= ( SELECT SUM(b) FROM t2 ));
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 index NULL a 4 NULL 2 Using index
1 PRIMARY t2 ALL NULL NULL NULL NULL 2 Using where
3 DEPENDENT SUBQUERY t1 ALL a NULL NULL NULL 2 Range checked for each record (index map: 0x1)
4 SUBQUERY t2 ALL NULL NULL NULL NULL 2
set @show_explain_probe_select_id=1;
set debug_dbug='+d,show_explain_probe_join_exec_start';
SELECT SUM(b) FROM ( SELECT * FROM t1 ) AS alias1, t2
WHERE b <= ANY (
SELECT a FROM t1
WHERE a = b + SLEEP(0.2) OR a >= ( SELECT SUM(b) FROM t2 ));
show explain for $thr2;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 index NULL a 4 NULL 2 Using index
1 PRIMARY t2 ALL NULL NULL NULL NULL 2 Using where
3 DEPENDENT SUBQUERY t1 ALL a NULL NULL NULL 2 Range checked for each record (index map: 0x1)
4 SUBQUERY t2 ALL NULL NULL NULL NULL 2
Warnings:
Note 1003 SELECT SUM(b) FROM ( SELECT * FROM t1 ) AS alias1, t2
WHERE b <= ANY (
SELECT a FROM t1
WHERE a = b + SLEEP(0.2) OR a >= ( SELECT SUM(b) FROM t2 ))
SUM(b)
0
set debug_dbug=@old_debug;
DROP TABLE t1,t2;
# End # End
drop table t0; drop table t0;
set debug_sync='RESET'; set debug_sync='RESET';

37
mysql-test/t/show_explain.test
View File

@ -1128,9 +1128,44 @@ set names default;
--error ER_SET_CONSTANTS_ONLY --error ER_SET_CONSTANTS_ONLY
show explain for foo; show explain for foo;
--echo #
--echo # MDEV-411: SHOW EXPLAIN: For dependent subquery EXPLAIN produces type=index, key, 'Using where; Using index',
--echo # while SHOW EXPLAIN says type=ALL, no key, 'Range checked for each record'
--echo #
CREATE TABLE t1 (a INT NOT NULL, KEY(a)) ENGINE=MyISAM;
INSERT INTO t1 VALUES (7),(0);
CREATE TABLE t2 (b INT NOT NULL) ENGINE=MyISAM;
INSERT INTO t2 VALUES (0),(8);
explain
SELECT SUM(b) FROM ( SELECT * FROM t1 ) AS alias1, t2
WHERE b <= ANY (
SELECT a FROM t1
WHERE a = b + SLEEP(0.2) OR a >= ( SELECT SUM(b) FROM t2 ));
set @show_explain_probe_select_id=1;
set debug_dbug='+d,show_explain_probe_join_exec_start';
send
SELECT SUM(b) FROM ( SELECT * FROM t1 ) AS alias1, t2
WHERE b <= ANY (
SELECT a FROM t1
WHERE a = b + SLEEP(0.2) OR a >= ( SELECT SUM(b) FROM t2 ));
connection default;
--source include/wait_condition.inc
evalp show explain for $thr2;
connection con1;
reap;
set debug_dbug=@old_debug;
DROP TABLE t1,t2;
--echo # End --echo # End
drop table t0; drop table t0;
connection default; connection default;
disconnect con1; disconnect con1;
set debug_sync='RESET'; set debug_sync='RESET';