| Bug #48052 | Valgrind warning - uninitialized value in init_read_record() - (records.cc:274) | ||
|---|---|---|---|
| Submitted: | 14 Oct 2009 18:58 | Modified: | 12 Mar 2010 17:14 |
| Reporter: | Patrick Crews | Email Updates: | |
| Status: | Closed | Impact on me: | |
| Category: | MySQL Server: Optimizer | Severity: | S3 (Non-critical) |
| Version: | 5.1,6.0 | OS: | Any |
| Assigned to: | Jørgen Løland | CPU Architecture: | Any |
| Tags: | uninitialised value, valgrind, warning | ||
[14 Oct 2009 18:58]
Patrick Crews
[27 Oct 2009 17:39]
Patrick Crews
MTR test case. Run with the --valgrind switch to repeat the error.
Attachment: bug48052_test.txt (text/plain), 8.05 KiB.
[6 Nov 2009 9:45]
Jørgen Løland
Very simplified testcase that fails in the same way: /*!50400 SET SESSION optimizer_switch = 'firstmatch=off,index_merge=off,index_merge_union=off,index_merge_sort_union=off,index_merge_intersection=off,loosescan=off,materialization=off,semijoin=off' */; /*!50400 SET SESSION engine_condition_pushdown = 'OFF' */; CREATE TABLE t1 ( pk int(11) NOT NULL, i int(11) DEFAULT NULL, v varchar(1) DEFAULT NULL, PRIMARY KEY (pk) ) ENGINE=MyISAM; INSERT INTO t1 VALUES (2,7,'m'); INSERT INTO t1 VALUES (3,9,'m'); SELECT v FROM t1 WHERE NOT pk > 0 HAVING v <= 't' ORDER BY pk; DROP TABLE t1;
[6 Nov 2009 13:44]
Jørgen Løland
The uninitialized variable is
select->cond->used_tables_cache
accessed through (item_cmpfunc.cc):
table_map
Item_cond::used_tables() const
{ // This caches used_tables
return used_tables_cache;
}
This Item_cond is an Item_cond_and item created in JOIN::exec() (sql_select.cc around line 2810):
if (!curr_table->select->cond)
curr_table->select->cond= sort_table_cond;
else // This should never happen
{
if (!(curr_table->select->cond=
new Item_cond_and(curr_table->select->cond, // ** HERE **
sort_table_cond)))
DBUG_VOID_RETURN;
/*
Item_cond_and do not need fix_fields for execution, its parameters
are fixed or do not need fix_fields, too
*/
curr_table->select->cond->quick_fix_field();
}
The correct value for used_tables_cache table_map is "OR" of the two arguments to the Item_cond_and constructor.
I see two possible solutions:
1) call fix_fields instead of quick_fix_field.
2) set used_tables_cache directly:
curr_table->select->cond->used_tables_cache= "item1"->u_t_c | "item2"->u_t_c
[9 Nov 2009 7:14]
Jørgen Løland
Another alternative: 3) Call curr_table->select->cond->update_used_tables() after quick_fix_field() Alternative 3 will update only the used_tables_cache variable in the item. However, although alternative 3 seems to be cheaper than 1, update_used_tables() recursively calls update_used_tables() on it's "sub-items". fix_fields() is only recursive if the "sub-items" have not already been fixed (and they have been fixed at this point).
[9 Nov 2009 9:35]
Bugs System
A patch for this bug has been committed. After review, it may be pushed to the relevant source trees for release in the next version. You can access the patch from: http://lists.mysql.com/commits/89746 3202 Jorgen Loland 2009-11-09 Bug#48052: Valgrind warning - uninitialized value in init_read_record() - (records.cc:274) Item_cond::used_tables_cache was accessed in records.cc#init_read_record() without being initialized. It had not been initialized because it was wrongly assumed that the Item's variables would not be accessed, and hence quick_fix_field() was used instead of fix_fields() to save a few CPU cycles at creation time. The fix is to properly initilize the Item by replacing quick_fix_field() with fix_fields(). @ mysql-test/r/select.result Add test for BUG#48052 @ mysql-test/t/select.test Add test for BUG#48052 @ sql/sql_select.cc Properly initialize Item_cond_and by calling fix_fields (instead of quick_fix_field) when the Item that "ANDs" WHERE clause conditions with HAVING clause conditions is created.
[13 Nov 2009 10:17]
Bugs System
A patch for this bug has been committed. After review, it may be pushed to the relevant source trees for release in the next version. You can access the patch from: http://lists.mysql.com/commits/90322 3200 Jorgen Loland 2009-11-13 Bug#48052: Valgrind warning - uninitialized value in init_read_record() - (records.cc:274) Item_cond::used_tables_cache was accessed in records.cc#init_read_record() without being initialized. It had not been initialized because it was wrongly assumed that the Item's variables would not be accessed, and hence quick_fix_field() was used instead of fix_fields() to save a few CPU cycles at creation time. The fix is to properly initilize the Item by replacing quick_fix_field() with fix_fields(). @ mysql-test/r/select.result Add test for BUG#48052 @ mysql-test/t/select.test Add test for BUG#48052 @ sql/sql_select.cc Properly initialize Item_cond_and by calling fix_fields (instead of quick_fix_field) when the Item that "ANDs" WHERE clause conditions with HAVING clause conditions is created.
[13 Nov 2009 11:22]
Bugs System
A patch for this bug has been committed. After review, it may be pushed to the relevant source trees for release in the next version. You can access the patch from: http://lists.mysql.com/commits/90332 3200 Jorgen Loland 2009-11-13 Bug#48052: Valgrind warning - uninitialized value in init_read_record() - (records.cc:274) Item_cond::used_tables_cache was accessed in records.cc#init_read_record() without being initialized. It had not been initialized because it was wrongly assumed that the Item's variables would not be accessed, and hence quick_fix_field() was used instead of fix_fields() to save a few CPU cycles at creation time. The fix is to properly initilize the Item by replacing quick_fix_field() with fix_fields(). @ mysql-test/r/select.result Add test for BUG#48052 @ mysql-test/t/select.test Add test for BUG#48052 @ sql/sql_select.cc Properly initialize Item_cond_and by calling fix_fields (instead of quick_fix_field) when the Item that "ANDs" WHERE clause conditions with HAVING clause conditions is created.
[13 Nov 2009 11:26]
Bugs System
A patch for this bug has been committed. After review, it may be pushed to the relevant source trees for release in the next version. You can access the patch from: http://lists.mysql.com/commits/90334 3681 Jorgen Loland 2009-11-13 [merge] Merge BUG#48052 from mysql-5.1-bugteam to mysql-pe
[13 Nov 2009 11:32]
Bugs System
A patch for this bug has been committed. After review, it may be pushed to the relevant source trees for release in the next version. You can access the patch from: http://lists.mysql.com/commits/90335 3682 Jorgen Loland 2009-11-13 Turning engine_condition_pushdown off for test of BUG#48052 in the 6.0 codebase
[13 Nov 2009 11:34]
Jørgen Løland
Pushed to mysql-5.1-bugteam and mysql-pe
[2 Dec 2009 8:03]
Bugs System
Pushed into 5.1.42 (revid:joro@sun.com-20091202080033-mndu4sxwx19lz2zs) (version source revid:davi.arnaut@sun.com-20091125130912-d7hrln14ef7y5d7i) (merge vers: 5.1.42) (pib:13)
[16 Dec 2009 8:35]
Bugs System
Pushed into 6.0.14-alpha (revid:alik@sun.com-20091216083311-xorsasf5kopjxshf) (version source revid:alik@sun.com-20091214191830-wznm8245ku8xo702) (merge vers: 6.0.14-alpha) (pib:14)
[16 Dec 2009 8:42]
Bugs System
Pushed into 5.5.0-beta (revid:alik@sun.com-20091216082430-s0gtzibcgkv4pqul) (version source revid:alexey.kopytov@sun.com-20091124083136-iqm136jm31sfdwg3) (merge vers: 5.5.0-beta) (pib:14)
[16 Dec 2009 8:48]
Bugs System
Pushed into mysql-next-mr (revid:alik@sun.com-20091216083231-rp8ecpnvkkbhtb27) (version source revid:alik@sun.com-20091212203859-fx4rx5uab47wwuzd) (merge vers: 5.6.0-beta) (pib:14)
[18 Dec 2009 1:53]
Paul DuBois
No changelog entry needed. Little user impact.
[16 Feb 2010 15:05]
Bugs System
A patch for this bug has been committed. After review, it may be pushed to the relevant source trees for release in the next version. You can access the patch from: http://lists.mysql.com/commits/100517 3344 Sergey Glukhov 2010-02-16 Bug#50995 Having clause on subquery result produces incorrect results. This is the result of bug#48052 fix. The problem is that we can not use cond->fix_fields(thd, 0) here as it will break condition if it's AND condition. In our case fix_fields() cuts off 'having' condition. The fix: reverted fix_fields() to quick_fix_field() and updated cond->used_tables_cache with appropriate value. @ mysql-test/r/having.result test result @ mysql-test/t/having.test test case @ sql/sql_select.cc reverted fix_fields() to quick_fix_field() and updated cond->used_tables_cache with appropriate value.
[12 Mar 2010 14:06]
Bugs System
Pushed into 5.1.44-ndb-7.0.14 (revid:jonas@mysql.com-20100312135944-t0z8s1da2orvl66x) (version source revid:jonas@mysql.com-20100312115609-woou0te4a6s4ae9y) (merge vers: 5.1.44-ndb-7.0.14) (pib:16)
[12 Mar 2010 14:22]
Bugs System
Pushed into 5.1.44-ndb-6.2.19 (revid:jonas@mysql.com-20100312134846-tuqhd9w3tv4xgl3d) (version source revid:jonas@mysql.com-20100312060623-mx6407w2vx76h3by) (merge vers: 5.1.44-ndb-6.2.19) (pib:16)
[12 Mar 2010 14:36]
Bugs System
Pushed into 5.1.44-ndb-6.3.33 (revid:jonas@mysql.com-20100312135724-xcw8vw2lu3mijrhn) (version source revid:jonas@mysql.com-20100312103652-snkltsd197l7q2yg) (merge vers: 5.1.44-ndb-6.3.33) (pib:16)
[12 Mar 2010 17:14]
Paul DuBois
No changelog entry needed.
