Hi Timour, As discussed on the phone call: - Let's add a separate MDEV item to add "the assert". - Ok to push tis patch.
On Wed, May 30, 2012 at 07:12:33PM +0300, Timour Katchaounov wrote: > Sergey, > > Could you please review yet another bug fix for expensive subqueries > executed during optimiziation. > > Timour > > ------------------------------------------------------------ > revno: 3535 > revision-id: [email protected] > parent: [email protected] > fixes bug(s): https://launchpad.net/bugs/1006231 > committer: [email protected] > branch nick: 5.3 > timestamp: Wed 2012-05-30 19:10:18 +0300 > message: > Fix for bug lp:1006231 > > Analysis: > > When a subquery that needs a temp table is executed during > the prepare or optimize phase of the outer query, at the end > of the subquery execution all the JOIN_TABs of the subquery > are replaced by a new JOIN_TAB that selects from the temp table. > However that temp table has no corresponding TABLE_LIST. > Once EXPLAIN execution reaches its last phase, it tries to print > the names of the subquery tables through its TABLE_LISTs, but in > the case of this bug there is no such TABLE_LIST (it is NULL), > hence a crash. > > Solution: > The fix is to block subquery evaluation inside > Item_func_like::fix_fields and Item_func_like::select_optimize() > using the Item::is_expensive() test. > === modified file 'mysql-test/r/subselect_innodb.result' > --- a/mysql-test/r/subselect_innodb.result 2012-05-20 12:57:29 +0000 > +++ b/mysql-test/r/subselect_innodb.result 2012-05-30 16:10:18 +0000 > @@ -365,4 +365,19 @@ GROUP BY 1 > MAX( f1 ) > NULL > drop table t1, t2, t3; > +# > +# LP BUG#1006231 crash in select_describe > +# > +create table t1(a1 int) ENGINE=InnoDB; > +insert into t1 values (1); > +explain > +select 1 from t1 where 1 like (select 1 from t1 where 1 <=> (select 1 from > t1 group by a1)); > +id select_type table type possible_keys key key_len ref > rows Extra > +1 PRIMARY t1 ALL NULL NULL NULL NULL 1 > +2 SUBQUERY t1 ALL NULL NULL NULL NULL 1 > > +3 SUBQUERY t1 ALL NULL NULL NULL NULL 1 > Using temporary; Using filesort > +select 1 from t1 where 1 like (select 1 from t1 where 1 <=> (select 1 from > t1 group by a1)); > +1 > +1 > +drop table t1; > set optimizer_switch=@subselect_innodb_tmp; > > === modified file 'mysql-test/t/subselect_innodb.test' > --- a/mysql-test/t/subselect_innodb.test 2012-05-20 12:57:29 +0000 > +++ b/mysql-test/t/subselect_innodb.test 2012-05-30 16:10:18 +0000 > @@ -356,4 +356,16 @@ WHERE f2 >= ( > > drop table t1, t2, t3; > > +--echo # > +--echo # LP BUG#1006231 crash in select_describe > +--echo # > + > +create table t1(a1 int) ENGINE=InnoDB; > +insert into t1 values (1); > +explain > +select 1 from t1 where 1 like (select 1 from t1 where 1 <=> (select 1 from > t1 group by a1)); > +select 1 from t1 where 1 like (select 1 from t1 where 1 <=> (select 1 from > t1 group by a1)); > +drop table t1; > + > + > set optimizer_switch=@subselect_innodb_tmp; > > === modified file 'sql/item_cmpfunc.cc' > --- a/sql/item_cmpfunc.cc 2012-05-20 12:57:29 +0000 > +++ b/sql/item_cmpfunc.cc 2012-05-30 16:10:18 +0000 > @@ -4656,7 +4656,7 @@ longlong Item_func_like::val_int() > > Item_func::optimize_type Item_func_like::select_optimize() const > { > - if (args[1]->const_item()) > + if (args[1]->const_item() && !args[1]->is_expensive()) > { > String* res2= args[1]->val_str((String *)&cmp.value2); > const char *ptr2; > @@ -4743,7 +4743,8 @@ bool Item_func_like::fix_fields(THD *thd > We could also do boyer-more for non-const items, but as we would have > to > recompute the tables for each row it's not worth it. > */ > - if (args[1]->const_item() && !use_strnxfrm(collation.collation)) > + if (args[1]->const_item() && !use_strnxfrm(collation.collation) && > + !args[1]->is_expensive()) > { > String* res2 = args[1]->val_str(&cmp.value2); > if (!res2) > > _______________________________________________ > commits mailing list > [email protected] > https://lists.askmonty.org/cgi-bin/mailman/listinfo/commits -- BR Sergei -- Sergei Petrunia, Software Developer Monty Program AB, http://askmonty.org Blog: http://s.petrunia.net/blog _______________________________________________ Mailing list: https://launchpad.net/~maria-developers Post to : [email protected] Unsubscribe : https://launchpad.net/~maria-developers More help : https://help.launchpad.net/ListHelp
