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Fixed LP bug #953649.

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Do not call, directly or indirectly, SQL_SELECT::test_quick_select()
for derived materialized tables / views when optimizing joins referring
to these tables / views to get cost estimates of materialization.
The current code does not create B-tree indexes for materialized 
derived tables / views. So now it's not possible to get any estimates
for ranges conditions over the results of the materialization.

The function mysql_derived_create() must take into account the fact
that array of the KEY structures specifying the keys over a derived
table / view may be moved after the optimization phase if the
derived table / view  is materialized.
This commit is contained in:
Igor Babaev
2012-03-13 13:34:20 -07:00
parent 223483aedf
commit c1f5e25c04
4 changed files with 81 additions and 7 deletions
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38
mysql-test/r/derived_view.result
View File

@ -1960,6 +1960,42 @@ ON ( COLUMNS.TABLE_SCHEMA = UNIQUES.TABLE_SCHEMA);
COUNT(*) > 0
1
DROP TABLE t1;
set SESSION optimizer_switch= @save_optimizer_switch;
SET SESSION optimizer_switch= @save_optimizer_switch;
#
# LP BUG#953649: crash when estimating the cost of a look-up
# into a derived table to be materialized
#
CREATE TABLE t1 (a int);
INSERT INTO t1 VALUES (132);
CREATE TABLE t2 (b int, c varchar(256));
INSERT INTO t2 VALUES (132,'test1'), (120,'text2'), (132,'text3');
CREATE VIEW v AS
SELECT b, GROUP_CONCAT(c) AS gc FROM t2 GROUP BY b;
SET @save_optimizer_switch=@@optimizer_switch;
SET SESSION optimizer_switch='derived_merge=off';
SET SESSION optimizer_switch='derived_with_keys=off';
EXPLAIN
SELECT * FROM t1, v WHERE a = b;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 system NULL NULL NULL NULL 1
1 PRIMARY <derived2> ALL NULL NULL NULL NULL 3 Using where
2 DERIVED t2 ALL NULL NULL NULL NULL 3 Using filesort
SELECT * FROM t1, v WHERE a = b;
a b gc
132 132 test1,text3
SET SESSION optimizer_switch='derived_merge=on';
SET SESSION optimizer_switch='derived_with_keys=on';
EXPLAIN
SELECT * FROM t1, v WHERE a = b;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 system NULL NULL NULL NULL 1
1 PRIMARY <derived2> ref key0 key0 5 const 0
2 DERIVED t2 ALL NULL NULL NULL NULL 3 Using filesort
SELECT * FROM t1, v WHERE a = b;
a b gc
132 132 test1,text3
SET SESSION optimizer_switch= @save_optimizer_switch;
DROP VIEW v;
DROP TABLE t1,t2;
set optimizer_switch=@exit_optimizer_switch;
set join_cache_level=@exit_join_cache_level;

35
mysql-test/t/derived_view.test
View File

@ -1345,7 +1345,40 @@ SELECT COUNT(*) > 0
DROP TABLE t1;
set SESSION optimizer_switch= @save_optimizer_switch;
SET SESSION optimizer_switch= @save_optimizer_switch;
--echo #
--echo # LP BUG#953649: crash when estimating the cost of a look-up
--echo # into a derived table to be materialized
--echo #
CREATE TABLE t1 (a int);
INSERT INTO t1 VALUES (132);
CREATE TABLE t2 (b int, c varchar(256));
INSERT INTO t2 VALUES (132,'test1'), (120,'text2'), (132,'text3');
CREATE VIEW v AS
SELECT b, GROUP_CONCAT(c) AS gc FROM t2 GROUP BY b;
SET @save_optimizer_switch=@@optimizer_switch;
SET SESSION optimizer_switch='derived_merge=off';
SET SESSION optimizer_switch='derived_with_keys=off';
EXPLAIN
SELECT * FROM t1, v WHERE a = b;
SELECT * FROM t1, v WHERE a = b;
SET SESSION optimizer_switch='derived_merge=on';
SET SESSION optimizer_switch='derived_with_keys=on';
EXPLAIN
SELECT * FROM t1, v WHERE a = b;
SELECT * FROM t1, v WHERE a = b;
SET SESSION optimizer_switch= @save_optimizer_switch;
DROP VIEW v;
DROP TABLE t1,t2;
# The following command must be the last one the file
set optimizer_switch=@exit_optimizer_switch;

1
sql/sql_derived.cc
View File

@ -811,6 +811,7 @@ bool mysql_derived_create(THD *thd, LEX *lex, TABLE_LIST *derived)
select_union *result= (select_union*)unit->result;
if (table->s->db_type() == TMP_ENGINE_HTON)
{
result->tmp_table_param.keyinfo= table->s->key_info;
if (create_internal_tmp_table(table, result->tmp_table_param.keyinfo,
result->tmp_table_param.start_recinfo,
&result->tmp_table_param.recinfo,

6
sql/sql_select.cc
View File

@ -3513,12 +3513,16 @@ make_join_statistics(JOIN *join, List<TABLE_LIST> &tables_list,
Perform range analysis if there are keys it could use (1).
Don't do range analysis if we're on the inner side of an outer join (2).
Do range analysis if we're on the inner side of a semi-join (3).
Don't do range analysis for materialized subqueries (4).
Don't do range analysis for materialized derived tables (5)
*/
if (!s->const_keys.is_clear_all() && // (1)
(!s->table->pos_in_table_list->embedding || // (2)
(s->table->pos_in_table_list->embedding && // (3)
s->table->pos_in_table_list->embedding->sj_on_expr)) && // (3)
!s->table->is_filled_at_execution())
!s->table->is_filled_at_execution() && // (4)
!(s->table->pos_in_table_list->derived && // (5)
s->table->pos_in_table_list->is_materialized_derived())) // (5)
{
ha_rows records;
SQL_SELECT *select;