[MDEV-4657] SQ pushdown: Valgrind warnings (Conditional jump or move depends on uninitialised value) in compare_items_by_cost Created: 2013-06-13  Updated: 2013-08-09  Resolved: 2013-08-09

Status: Closed
Project: MariaDB Server
Component/s: None
Affects Version/s: None
Fix Version/s: 10.0.4

Type: Bug Priority: Major
Reporter: Elena Stepanova Assignee: Timour Katchaounov (Inactive)
Resolution: Fixed Votes: 0
Labels: None

Issue Links:
Relates
relates to MDEV-83 Cost-based choice for the pushdown of... Stalled

 Description    

==6997== Thread 4:
 
==6997== Conditional jump or move depends on uninitialised value(s)
 
==6997==    at 0x67C73D: compare_items_by_cost(Item*, Item*, void*) (sql_select.cc:18677)
 
==6997==    by 0x6913F3: void bubble_sort<Item>(List<Item>*, int (*)(Item*, Item*, void*), void*) (sql_list.h:599)
 
==6997==    by 0x67C9E5: make_cond_for_table_from_pred(THD*, Item*, Item*, unsigned long long, unsigned long long, int, bool, bool) (sql_select.cc:18737)
 
==6997==    by 0x67C68A: make_cond_for_table(THD*, Item*, unsigned long long, unsigned long long, int, bool, bool) (sql_select.cc:18666)
 
==6997==    by 0x6660D4: make_join_select(JOIN*, SQL_SELECT*, Item*) (sql_select.cc:9273)
 
==6997==    by 0x650967: JOIN::optimize_inner() (sql_select.cc:1494)
 
==6997==    by 0x64ED17: JOIN::optimize() (sql_select.cc:1008)
 
==6997==    by 0x6569FE: mysql_select(THD*, Item***, TABLE_LIST*, unsigned int, List<Item>&, Item*, unsigned int, st_order*, st_order*, Item*, st_order*, unsigned long long, select_result*, st_select_lex_unit*, st_select_lex*) (sql_select.cc:3233)
 
==6997==    by 0x64D188: handle_select(THD*, LEX*, select_result*, unsigned long) (sql_select.cc:376)
 
==6997==    by 0x62251B: execute_sqlcom_select(THD*, TABLE_LIST*) (sql_parse.cc:4804)
 
==6997==    by 0x61ABBC: mysql_execute_command(THD*) (sql_parse.cc:2268)
 
==6997==    by 0x624D86: mysql_parse(THD*, char*, unsigned int, Parser_state*) (sql_parse.cc:5927)
 
==6997==    by 0x617EF7: dispatch_command(enum_server_command, THD*, char*, unsigned int) (sql_parse.cc:1091)
 
==6997==    by 0x617426: do_command(THD*) (sql_parse.cc:810)
 
==6997==    by 0x732E67: do_handle_one_connection(THD*) (sql_connect.cc:1266)
 
==6997==    by 0x732BD5: handle_one_connection (sql_connect.cc:1181)
 
==6997== Conditional jump or move depends on uninitialised value(s)
 
==6997==    at 0x67C743: compare_items_by_cost(Item*, Item*, void*) (sql_select.cc:18677)
 
==6997==    by 0x6913F3: void bubble_sort<Item>(List<Item>*, int (*)(Item*, Item*, void*), void*) (sql_list.h:599)
 
==6997==    by 0x67C9E5: make_cond_for_table_from_pred(THD*, Item*, Item*, unsigned long long, unsigned long long, int, bool, bool) (sql_select.cc:18737)
 
==6997==    by 0x67C68A: make_cond_for_table(THD*, Item*, unsigned long long, unsigned long long, int, bool, bool) (sql_select.cc:18666)
 
==6997==    by 0x6660D4: make_join_select(JOIN*, SQL_SELECT*, Item*) (sql_select.cc:9273)
 
==6997==    by 0x650967: JOIN::optimize_inner() (sql_select.cc:1494)
 
==6997==    by 0x64ED17: JOIN::optimize() (sql_select.cc:1008)
 
==6997==    by 0x6569FE: mysql_select(THD*, Item***, TABLE_LIST*, unsigned int, List<Item>&, Item*, unsigned int, st_order*, st_order*, Item*, st_order*, unsigned long long, select_result*, st_select_lex_unit*, st_select_lex*) (sql_select.cc:3233)
 
==6997==    by 0x64D188: handle_select(THD*, LEX*, select_result*, unsigned long) (sql_select.cc:376)
 
==6997==    by 0x62251B: execute_sqlcom_select(THD*, TABLE_LIST*) (sql_parse.cc:4804)
 
==6997==    by 0x61ABBC: mysql_execute_command(THD*) (sql_parse.cc:2268)
 
==6997==    by 0x624D86: mysql_parse(THD*, char*, unsigned int, Parser_state*) (sql_parse.cc:5927)
 
==6997==    by 0x617EF7: dispatch_command(enum_server_command, THD*, char*, unsigned int) (sql_parse.cc:1091)
 
==6997==    by 0x617426: do_command(THD*) (sql_parse.cc:810)
 
==6997==    by 0x732E67: do_handle_one_connection(THD*) (sql_connect.cc:1266)
 
==6997==    by 0x732BD5: handle_one_connection (sql_connect.cc:1181)
 
==6997== Conditional jump or move depends on uninitialised value(s)
 
==6997==    at 0x67C75F: compare_items_by_cost(Item*, Item*, void*) (sql_select.cc:18679)
 
==6997==    by 0x6913F3: void bubble_sort<Item>(List<Item>*, int (*)(Item*, Item*, void*), void*) (sql_list.h:599)
 
==6997==    by 0x67C9E5: make_cond_for_table_from_pred(THD*, Item*, Item*, unsigned long long, unsigned long long, int, bool, bool) (sql_select.cc:18737)
 
==6997==    by 0x67C68A: make_cond_for_table(THD*, Item*, unsigned long long, unsigned long long, int, bool, bool) (sql_select.cc:18666)
 
==6997==    by 0x6660D4: make_join_select(JOIN*, SQL_SELECT*, Item*) (sql_select.cc:9273)
 
==6997==    by 0x650967: JOIN::optimize_inner() (sql_select.cc:1494)
 
==6997==    by 0x64ED17: JOIN::optimize() (sql_select.cc:1008)
 
==6997==    by 0x6569FE: mysql_select(THD*, Item***, TABLE_LIST*, unsigned int, List<Item>&, Item*, unsigned int, st_order*, st_order*, Item*, st_order*, unsigned long long, select_result*, st_select_lex_unit*, st_select_lex*) (sql_select.cc:3233)
 
==6997==    by 0x64D188: handle_select(THD*, LEX*, select_result*, unsigned long) (sql_select.cc:376)
 
==6997==    by 0x62251B: execute_sqlcom_select(THD*, TABLE_LIST*) (sql_parse.cc:4804)
 
==6997==    by 0x61ABBC: mysql_execute_command(THD*) (sql_parse.cc:2268)
 
==6997==    by 0x624D86: mysql_parse(THD*, char*, unsigned int, Parser_state*) (sql_parse.cc:5927)
 
==6997==    by 0x617EF7: dispatch_command(enum_server_command, THD*, char*, unsigned int) (sql_parse.cc:1091)
 
==6997==    by 0x617426: do_command(THD*) (sql_parse.cc:810)
 
==6997==    by 0x732E67: do_handle_one_connection(THD*) (sql_connect.cc:1266)
 

18670:static int compare_items_by_cost(Item* it1, Item* it2, void *arg)
 
18671:{
 
18672:  double cost1= 0, cost2= 0;
 
18673:
 
18674:  it1->walk(&Item::sum_cost_processor, false, (uchar*) &cost1);
 
18675:  it2->walk(&Item::sum_cost_processor, false, (uchar*) &cost2);
 
18676:
 
18677:  if (cost1 == cost2)
 
18678:    return 0;
 
18679:  if (cost1 > cost2)
 
18680:    return -1;
 
18681:  else
 
18682:    return 1;
 
18683:}

bzr version-info

revision-id: timour@askmonty.org-20130528122232-kisslvdw5vhrna0q
 
revno: 3550
 
branch-nick: 10.0-mdev83

Built with BUILD/compile-pentium-valgrind-max-no-ndb

Test case:

CREATE TABLE t1 (i1 INT, c1 CHAR(1)) ENGINE=MyISAM;
 
INSERT INTO t1 VALUES (1,'a'),(2,'b');
 
 
 
CREATE TABLE t2 (i2 INT, c2 CHAR(1)) ENGINE=MyISAM;
 
INSERT INTO t2 VALUES (3,'m'),(4,'n');
 
 
 
SELECT * FROM t1 STRAIGHT_JOIN t2 WHERE (i2 = i1) AND ( c2 , c1 )  IN ( SELECT 'f' , 'q' );

EXPLAIN:

SELECT * FROM t1 STRAIGHT_JOIN t2 WHERE (i2 = i1) AND ( c2 , c1 )  IN ( SELECT 'f' , 'q' );
 
id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 
1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	
1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where; Subqueries: 2; Using join buffer (flat, BNL join)
 
2	DEPENDENT SUBQUERY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
 
Warnings:
 
Note	1003	select `test`.`t1`.`i1` AS `i1`,`test`.`t1`.`c1` AS `c1`,`test`.`t2`.`i2` AS `i2`,`test`.`t2`.`c2` AS `c2` from `test`.`t1` straight_join `test`.`t2` where ((`test`.`t2`.`i2` = `test`.`t1`.`i1`) and <expr_cache><`test`.`t2`.`c2`,`test`.`t1`.`c1`>(<in_optimizer>((`test`.`t2`.`c2`,`test`.`t1`.`c1`),<exists>(select 'f','q' having (((<cache>(`test`.`t2`.`c2`) = 'f') or isnull('f')) and ((<cache>(`test`.`t1`.`c1`) = 'q') or isnull('q')) and <is_not_null_test>('f') and <is_not_null_test>('q'))))))



 Comments   
Comment by Elena Stepanova [ 2013-06-13 ]

Couldn't reproduce on current 10.0, which is why I connected it to SQ pushdown. If it's just a coincidence, please feel free to modify the summary and links and reassign to whoever it belongs.

Comment by Timour Katchaounov (Inactive) [ 2013-08-09 ]

Fix pushed to mdev-83.

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