SQ pushdown: Valgrind warnings (Conditional jump or move depends on uninitialised value) in best_extension_by_limited_search / greedy_search with expensive_pred_static_pushdown=on

SET optimizer_switch='expensive_pred_static_pushdown=on';

CREATE TABLE t1 (i INT) ENGINE=MyISAM;

INSERT INTO t1 VALUES (8),(18);

SELECT 1 FROM t1 WHERE i IN ( SELECT 8 UNION SELECT 8 );

==29718== Thread 4:

==29718== Conditional jump or move depends on uninitialised value(s)

==29718==    at 0x6619E3: best_extension_by_limited_search(JOIN*, unsigned long long, unsigned int, double, double, unsigned int, unsigned int, unsigned int) (sql_select.cc:7524)

==29718==    by 0x65FA54: greedy_search(JOIN*, unsigned long long, unsigned int, unsigned int, unsigned int) (sql_select.cc:6684)

==29718==    by 0x65F05A: choose_plan(JOIN*, unsigned long long) (sql_select.cc:6261)

==29718==    by 0x658F3E: make_join_statistics(JOIN*, List<TABLE_LIST>&, Item*, st_dynamic_array*) (sql_select.cc:3916)

==29718==    by 0x64FD9D: JOIN::optimize_inner() (sql_select.cc:1314)

==29718==    by 0x64ED17: JOIN::optimize() (sql_select.cc:1008)

==29718==    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)

==29718==    by 0x64D188: handle_select(THD*, LEX*, select_result*, unsigned long) (sql_select.cc:376)

==29718==    by 0x62251B: execute_sqlcom_select(THD*, TABLE_LIST*) (sql_parse.cc:4804)

==29718==    by 0x61ABBC: mysql_execute_command(THD*) (sql_parse.cc:2268)

==29718==    by 0x624D86: mysql_parse(THD*, char*, unsigned int, Parser_state*) (sql_parse.cc:5927)

==29718==    by 0x617EF7: dispatch_command(enum_server_command, THD*, char*, unsigned int) (sql_parse.cc:1091)

==29718==    by 0x617426: do_command(THD*) (sql_parse.cc:810)

==29718==    by 0x732E67: do_handle_one_connection(THD*) (sql_connect.cc:1266)

==29718==    by 0x732BD5: handle_one_connection (sql_connect.cc:1181)

==29718==    by 0x99CA4F: pfs_spawn_thread (pfs.cc:1015)

==29718== Conditional jump or move depends on uninitialised value(s)

==29718==    at 0x65FA94: greedy_search(JOIN*, unsigned long long, unsigned int, unsigned int, unsigned int) (sql_select.cc:6692)

==29718==    by 0x65F05A: choose_plan(JOIN*, unsigned long long) (sql_select.cc:6261)

==29718==    by 0x658F3E: make_join_statistics(JOIN*, List<TABLE_LIST>&, Item*, st_dynamic_array*) (sql_select.cc:3916)

==29718==    by 0x64FD9D: JOIN::optimize_inner() (sql_select.cc:1314)

==29718==    by 0x64ED17: JOIN::optimize() (sql_select.cc:1008)

==29718==    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)

==29718==    by 0x64D188: handle_select(THD*, LEX*, select_result*, unsigned long) (sql_select.cc:376)

==29718==    by 0x62251B: execute_sqlcom_select(THD*, TABLE_LIST*) (sql_parse.cc:4804)

==29718==    by 0x61ABBC: mysql_execute_command(THD*) (sql_parse.cc:2268)

==29718==    by 0x624D86: mysql_parse(THD*, char*, unsigned int, Parser_state*) (sql_parse.cc:5927)

==29718==    by 0x617EF7: dispatch_command(enum_server_command, THD*, char*, unsigned int) (sql_parse.cc:1091)

==29718==    by 0x617426: do_command(THD*) (sql_parse.cc:810)

==29718==    by 0x732E67: do_handle_one_connection(THD*) (sql_connect.cc:1266)

==29718==    by 0x732BD5: handle_one_connection (sql_connect.cc:1181)

==29718==    by 0x99CA4F: pfs_spawn_thread (pfs.cc:1015)

==29718==    by 0x545AE99: start_thread (pthread_create.c:308)

revision-id: timour@askmonty.org-20130611081135-rge7p00h8e9nhypj

revno: 3551

branch-nick: 10.0-mdev83

7522:        }

7523:

7524:        if (current_read_time < join->best_read)

7525:        {

7526:          memcpy((uchar*) join->best_positions, (uchar*) join->positions,

7527:                 sizeof(POSITION) * (idx + 1));

7528:          join->record_count= join->positions[idx].partial_join_cardinality;

7529:          join->best_read= current_read_time - 0.001;

7530:          /*

7531:            Store the current best choice of pushdown POSITIONs for all subqueries

7532:          */

6681:  do {

6682:    /* Find the extension of the current QEP with the lowest cost */

6683:    join->best_read= DBL_MAX;

6684:    if (best_extension_by_limited_search(join, remaining_tables, idx, record_count,

6685:                                         read_time, search_depth, prune_level,

6686:                                         use_cond_selectivity))

6687:      DBUG_RETURN(TRUE);

6688:    /*

6689:      'best_read < DBL_MAX' means that optimizer managed to find

6690:      some plan and updated 'best_positions' array accordingly.

6691:    */

6692:    DBUG_ASSERT(join->best_read < DBL_MAX); 

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	Using where; Subqueries: 2

2	DEPENDENT SUBQUERY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used

3	DEPENDENT UNION	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used

NULL	UNION RESULT	<union2,3>	ALL	NULL	NULL	NULL	NULL	NULL	NULL	

Warnings:

Note	1003	select 1 AS `1` from `test`.`t1` where <expr_cache><`test`.`t1`.`i`>(<in_optimizer>(`test`.`t1`.`i`,<exists>(select 8 having (<cache>(`test`.`t1`.`i`) = <ref_null_helper>(8)) union select 8 having (<cache>(`test`.`t1`.`i`) = <ref_null_helper>(8)))))