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This commit is contained in:
Igor Babaev 2012-01-18 15:28:13 -08:00
commit d92e84e083
7 changed files with 38 additions and 5 deletions
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17
mysql-test/r/derived_view.result
View file

@ -1889,5 +1889,22 @@ ORDER BY CONCAT(alias2.col_varchar_nokey);
col_varchar_key pk col_varchar_key col_varchar_nokey
set max_heap_table_size= @tmp_882994;
drop table t1,t2,t3;
#
# LP bug #917990: Bad estimate of #rows for derived table with LIMIT
#
CREATE TABLE t1 (a int);
INSERT INTO t1 VALUES
(8), (3), (4), (7), (9), (5), (1), (2);
SELECT * FROM (SELECT * FROM t1 LIMIT 3) t;
a
8
3
4
EXPLAIN
SELECT * FROM (SELECT * FROM t1 LIMIT 3) t;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY <derived2> ALL NULL NULL NULL NULL 3
2 DERIVED t1 ALL NULL NULL NULL NULL 8
DROP TABLE t1;
set optimizer_switch=@exit_optimizer_switch;
set join_cache_level=@exit_join_cache_level;

2
mysql-test/r/view.result
View file

@ -304,7 +304,7 @@ a+1
4
explain select * from v1;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY <derived2> ALL NULL NULL NULL NULL 4
1 PRIMARY <derived2> ALL NULL NULL NULL NULL 2
2 DERIVED t1 ALL NULL NULL NULL NULL 4 Using filesort
drop view v1;
drop table t1;

4
mysql-test/suite/vcol/r/vcol_view_innodb.result
View file

@ -107,7 +107,7 @@ MariaDB-5.3: the following EXPLAIN produces incorrect #rows for table t1.
MariaDB-5.3: this is expected to go away when FROM subquery optimizations are pushed
explain select * from v1;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY <derived2> ALL NULL NULL NULL NULL 4
1 PRIMARY <derived2> ALL NULL NULL NULL NULL 2
2 DERIVED t1 ALL NULL NULL NULL NULL 4 Using filesort
drop view v1;
create view v1 as select c+1 from t1 order by 1 desc limit 2;
@ -119,7 +119,7 @@ MariaDB-5.3: the following EXPLAIN produces incorrect #rows for table t1.
MariaDB-5.3: this is expected to go away when FROM subquery optimizations are pushed
explain select * from v1;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY <derived2> ALL NULL NULL NULL NULL 4
1 PRIMARY <derived2> ALL NULL NULL NULL NULL 2
2 DERIVED t1 ALL NULL NULL NULL NULL 4 Using filesort
drop view v1;
drop table t1;

4
mysql-test/suite/vcol/r/vcol_view_myisam.result
View file

@ -107,7 +107,7 @@ MariaDB-5.3: the following EXPLAIN produces incorrect #rows for table t1.
MariaDB-5.3: this is expected to go away when FROM subquery optimizations are pushed
explain select * from v1;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY <derived2> ALL NULL NULL NULL NULL 4
1 PRIMARY <derived2> ALL NULL NULL NULL NULL 2
2 DERIVED t1 ALL NULL NULL NULL NULL 4 Using filesort
drop view v1;
create view v1 as select c+1 from t1 order by 1 desc limit 2;
@ -119,7 +119,7 @@ MariaDB-5.3: the following EXPLAIN produces incorrect #rows for table t1.
MariaDB-5.3: this is expected to go away when FROM subquery optimizations are pushed
explain select * from v1;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY <derived2> ALL NULL NULL NULL NULL 4
1 PRIMARY <derived2> ALL NULL NULL NULL NULL 2
2 DERIVED t1 ALL NULL NULL NULL NULL 4 Using filesort
drop view v1;
drop table t1;

14
mysql-test/t/derived_view.test
View file

@ -1277,6 +1277,20 @@ ORDER BY CONCAT(alias2.col_varchar_nokey);
set max_heap_table_size= @tmp_882994;
drop table t1,t2,t3;
--echo #
--echo # LP bug #917990: Bad estimate of #rows for derived table with LIMIT
--echo #
CREATE TABLE t1 (a int);
INSERT INTO t1 VALUES
(8), (3), (4), (7), (9), (5), (1), (2);
SELECT * FROM (SELECT * FROM t1 LIMIT 3) t;
EXPLAIN
SELECT * FROM (SELECT * FROM t1 LIMIT 3) t;
DROP TABLE t1;
# The following command must be the last one the file
set optimizer_switch=@exit_optimizer_switch;
set join_cache_level=@exit_join_cache_level;

1
sql/sql_derived.cc
View file

@ -753,6 +753,7 @@ bool mysql_derived_optimize(THD *thd, LEX *lex, TABLE_LIST *derived)
if (!derived->is_merged_derived())
{
JOIN *join= first_select->join;
unit->set_limit(first_select);
unit->optimized= TRUE;
if ((res= join->optimize()))
goto err;

1
sql/sql_select.cc
View file

@ -3581,6 +3581,7 @@ make_join_statistics(JOIN *join, List<TABLE_LIST> &tables_list,
for (i= 0; i < join->table_count ; i++)
records*= join->best_positions[i].records_read ?
(ha_rows)join->best_positions[i].records_read : 1;
set_if_smaller(records, unit->select_limit_cnt);
join->select_lex->increase_derived_records(records);
}
}