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Fixed LP bug #892725.

Browse Source 
A non-first execution of a prepared statement missed a call of the
TABLE_LIST::process_index_hints() method in the code of the function
setup_tables().
At some scenarios this could lead to the choice of a quite inefficient
execution plan for the base query of the prepared statement.
This commit is contained in:
Igor Babaev
2011-11-20 04:53:07 -08:00
parent 5a4c91003a
commit 3c496ea9ad
3 changed files with 86 additions and 0 deletions
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57
mysql-test/r/ps.result
View File

@ -3058,3 +3058,60 @@ date('2010-10-10') between '2010-09-09' and ?
execute stmt using @a;
date('2010-10-10') between '2010-09-09' and ?
0
#
# Bug #892725: look-up is changed for a full scan when executing PS
#
create table t1 (a int primary key, b int);
insert into t1 values
(7,70), (3,40), (4,40), (8,70), (1,70), (9,50), (2,70);
prepare st from 'select * from t1 where a=8';
flush status;
execute st;
a b
8 70
show status like '%Handler_read%';
Variable_name Value
Handler_read_first 0
Handler_read_key 1
Handler_read_next 0
Handler_read_prev 0
Handler_read_rnd 0
Handler_read_rnd_next 0
flush status;
execute st;
a b
8 70
show status like '%Handler_read%';
Variable_name Value
Handler_read_first 0
Handler_read_key 1
Handler_read_next 0
Handler_read_prev 0
Handler_read_rnd 0
Handler_read_rnd_next 0
flush status;
select * from t1 use index() where a=3;
a b
3 40
show status like '%Handler_read%';
Variable_name Value
Handler_read_first 0
Handler_read_key 0
Handler_read_next 0
Handler_read_prev 0
Handler_read_rnd 0
Handler_read_rnd_next 8
flush status;
execute st;
a b
8 70
show status like '%Handler_read%';
Variable_name Value
Handler_read_first 0
Handler_read_key 1
Handler_read_next 0
Handler_read_prev 0
Handler_read_rnd 0
Handler_read_rnd_next 0
deallocate prepare st;
drop table t1;

27
mysql-test/t/ps.test
View File

@ -3119,3 +3119,30 @@ set @a='2010-08-08';
execute stmt using @a;
execute stmt using @a;
--echo #
--echo # Bug #892725: look-up is changed for a full scan when executing PS
--echo #
create table t1 (a int primary key, b int);
insert into t1 values
(7,70), (3,40), (4,40), (8,70), (1,70), (9,50), (2,70);
prepare st from 'select * from t1 where a=8';
flush status;
execute st;
show status like '%Handler_read%';
flush status;
execute st;
show status like '%Handler_read%';
flush status;
select * from t1 use index() where a=3;
show status like '%Handler_read%';
flush status;
execute st;
show status like '%Handler_read%';
deallocate prepare st;
drop table t1;

2
sql/sql_base.cc
View File

@ -7864,6 +7864,8 @@ bool setup_tables(THD *thd, Name_resolution_context *context,
table_list->table->map= table_list->map_exec;
table_list->table->maybe_null= table_list->maybe_null_exec;
table_list->table->pos_in_table_list= table_list;
if (table_list->process_index_hints(table_list->table))
DBUG_RETURN(1);
}
select_lex->leaf_tables.push_back(table_list);
}