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[SHOW] EXPLAIN UPDATE/DELETE, code re-structuring

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- If a subquery is correlated wrt a const table, it will change from
  being a "DEPENDENT SUBQUERY" into "SUBQUERY", at the end of its parent's 
  JOIN::optimize() call.  Handle this, update the subquery's QPF.
- Make show_explain.test to work
   = "Query plan already deleted" does not happen anymore.
   = Handle special case of queries that don't have top-level selects, like 
     SET x = (SELECT ...)
This commit is contained in:
Sergey Petrunya
2013-06-27 18:52:47 +04:00
parent 8b7bbcf4dc
commit d634638c56
4 changed files with 46 additions and 14 deletions
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33
mysql-test/r/show_explain.result
View File

@ -165,7 +165,11 @@ set @show_explain_probe_select_id=1;
set debug_dbug='+d,show_explain_probe_join_exec_end';
select a, (select max(a) from t0 b where b.a+a.a<10) from t0 a where a<1;
show explain for $thr2;
ERROR HY000: Target is not running an EXPLAINable command
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY a ALL NULL NULL NULL NULL 10 Using where
2 DEPENDENT SUBQUERY b ALL NULL NULL NULL NULL 10 Using where
Warnings:
Note 1003 select a, (select max(a) from t0 b where b.a+a.a<10) from t0 a where a<1
a (select max(a) from t0 b where b.a+a.a<10)
0 9
set debug_dbug=@old_debug;
@ -343,7 +347,11 @@ SELECT alias.a FROM t2, ( SELECT * FROM t2 ) AS alias GROUP BY alias.a;
# FIXED by "conservative assumptions about when QEP is available" fix:
# NOTE: current code will not show "Using join buffer":
show explain for $thr2;
ERROR HY000: Target is not running an EXPLAINable command
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 5 Using temporary; Using filesort
1 SIMPLE t2 ALL NULL NULL NULL NULL 5 Using join buffer (flat, BNL join)
Warnings:
Note 1003 SELECT alias.a FROM t2, ( SELECT * FROM t2 ) AS alias GROUP BY alias.a
a
1
2
@ -428,7 +436,10 @@ set @show_explain_probe_select_id=1;
set debug_dbug='+d,show_explain_probe_join_exec_end';
select * from t0 where 1>10;
show explain for $thr2;
ERROR HY000: Target is not running an EXPLAINable command
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Impossible WHERE
Warnings:
Note 1003 select * from t0 where 1>10
a
set debug_dbug=@old_debug;
#
@ -440,7 +451,10 @@ set @show_explain_probe_select_id=1;
set debug_dbug='+d,show_explain_probe_join_exec_end';
select * from t0,t3 where t3.a=112233;
show explain for $thr2;
ERROR HY000: Target is not running an EXPLAINable command
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE NULL NULL NULL NULL NULL NULL NULL no matching row in const table
Warnings:
Note 1003 select * from t0,t3 where t3.a=112233
a a
set debug_dbug=@old_debug;
drop table t3;
@ -545,7 +559,12 @@ set @show_explain_probe_select_id=1;
set debug_dbug='+d,show_explain_probe_join_exec_end';
SELECT * FROM t2 WHERE (5, 78) IN (SELECT `a1`, MAX(`a1`) FROM t2 GROUP BY `a1`);
show explain for $thr2;
ERROR HY000: Target is not running an EXPLAINable command
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY <subquery2> const distinct_key distinct_key 8 const,const 1
1 PRIMARY t2 ALL NULL NULL NULL NULL 20 Using join buffer (flat, BNL join)
2 MATERIALIZED t2 index NULL a1 4 NULL 20 Using index
Warnings:
Note 1003 SELECT * FROM t2 WHERE (5, 78) IN (SELECT `a1`, MAX(`a1`) FROM t2 GROUP BY `a1`)
pk a1
set debug_dbug=@old_debug;
DROP TABLE t2;
@ -651,7 +670,7 @@ SELECT a + 1 FROM v1;
show explain for $thr2;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY <derived2> ALL NULL NULL NULL NULL 2
2 DERIVED NULL NULL NULL NULL NULL NULL NULL Query plan already deleted
2 DERIVED t1 ALL NULL NULL NULL NULL 2
Warnings:
Note 1003 SELECT a + 1 FROM v1
a + 1
@ -1061,7 +1080,7 @@ show explain for $thr2;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY alias1 ALL NULL NULL NULL NULL 14
1 PRIMARY t2 ALL NULL NULL NULL NULL 20
3 SUBQUERY NULL NULL NULL NULL NULL NULL NULL Query plan already deleted
3 SUBQUERY t3 ALL NULL NULL NULL NULL 20 Using where
Warnings:
Note 1003 SELECT max(a+b+c) FROM t1 AS alias1, ( SELECT * FROM t2 ) AS alias
WHERE EXISTS ( SELECT * FROM t3 WHERE b = c ) OR a <= 10

9
mysql-test/t/show_explain.test
View File

@ -202,7 +202,6 @@ set debug_dbug='+d,show_explain_probe_join_exec_end';
send select a, (select max(a) from t0 b where b.a+a.a<10) from t0 a where a<1;
connection default;
--source include/wait_condition.inc
--error ER_TARGET_NOT_EXPLAINABLE
evalp show explain for $thr2;
connection con1;
reap;
@ -349,7 +348,7 @@ connection default;
--source include/wait_condition.inc
--echo # FIXED by "conservative assumptions about when QEP is available" fix:
--echo # NOTE: current code will not show "Using join buffer":
--error ER_TARGET_NOT_EXPLAINABLE
#--error ER_TARGET_NOT_EXPLAINABLE
evalp show explain for $thr2;
connection con1;
reap;
@ -428,7 +427,7 @@ set debug_dbug='+d,show_explain_probe_join_exec_end';
send select * from t0 where 1>10;
connection default;
--source include/wait_condition.inc
--error ER_TARGET_NOT_EXPLAINABLE
#--error ER_TARGET_NOT_EXPLAINABLE
evalp show explain for $thr2;
connection con1;
reap;
@ -444,7 +443,7 @@ set debug_dbug='+d,show_explain_probe_join_exec_end';
send select * from t0,t3 where t3.a=112233;
connection default;
--source include/wait_condition.inc
--error ER_TARGET_NOT_EXPLAINABLE
# --error ER_TARGET_NOT_EXPLAINABLE
evalp show explain for $thr2;
connection con1;
reap;
@ -540,7 +539,7 @@ send
SELECT * FROM t2 WHERE (5, 78) IN (SELECT `a1`, MAX(`a1`) FROM t2 GROUP BY `a1`);
connection default;
--source include/wait_condition.inc
--error ER_TARGET_NOT_EXPLAINABLE
# --error ER_TARGET_NOT_EXPLAINABLE
evalp show explain for $thr2;
connection con1;
reap;