path: root/mysql-test/main/explain.test

#
# Test of different EXPLAINs

--disable_warnings
drop table if exists t1;
--enable_warnings
create table t1 (id int not null, str char(10), unique(str));
explain select * from t1;
insert into t1 values (1, null),(2, null),(3, "foo"),(4, "bar");
select * from t1 where str is null;
select * from t1 where str="foo";
explain select * from t1 where str is null;
explain select * from t1 where str="foo";
explain select * from t1 ignore key (str) where str="foo";
explain select * from t1 use key (str,str) where str="foo";

#The following should give errors
--error 1176
explain select * from t1 use key (str,str,foo) where str="foo";
--error 1176
explain select * from t1 ignore key (str,str,foo) where str="foo";
drop table t1;

explain select 1;

create table t1 (a int not null);
explain select count(*) from t1;
insert into t1 values(1);
explain select count(*) from t1;
insert into t1 values(1);
explain select count(*) from t1;
drop table t1;

#
# Bug #3403 Wrong encoding in EXPLAIN SELECT output
#
set names koi8r;
create table ��� (���0 int, ���1 int, key ���0 (���0), key ���01 (���0,���1));
insert into ��� (���0) values (1);
insert into ��� (���0) values (2);
explain select ���0 from ��� where ���0=1;
drop table ���;
set names latin1;

# End of 4.1 tests


#
# Bug#15463: EXPLAIN SELECT..INTO hangs the client (QB, command line)
#
select 3 into @v1;
explain select 3 into @v1;

#
# Bug#22331: Wrong WHERE in EXPLAIN EXTENDED when all expressions were
#            optimized away.
#
create table t1(f1 int, f2 int);
insert into t1 values (1,1);
create view v1 as select * from t1 where f1=1;
explain extended select * from v1 where f2=1;
explain extended select * from t1 where 0;
explain extended select * from t1 where 1;
explain extended select * from t1 having 0;
explain extended select * from t1 having 1;
drop view v1;
drop table t1;

#
# Bug #32241: memory corruption due to large index map in 'Range checked for 
#             each record'
#

CREATE TABLE t1(c INT);
INSERT INTO t1 VALUES (),();

CREATE TABLE t2 (b INT,
KEY(b),KEY(b),KEY(b),KEY(b),KEY(b),
KEY(b),KEY(b),KEY(b),KEY(b),KEY(b),
KEY(b),KEY(b),KEY(b),KEY(b),KEY(b),
KEY(b),KEY(b),KEY(b),KEY(b),KEY(b),
KEY(b),KEY(b),KEY(b),KEY(b),KEY(b),
KEY(b),KEY(b),KEY(b),KEY(b),KEY(b),
KEY(b),KEY(b),KEY(b),KEY(b),KEY(b),
KEY(b),KEY(b),KEY(b),KEY(b),KEY(b));

INSERT INTO t2 VALUES (),(),();

# We only need to make sure that there is no buffer overrun and the index map
# is displayed correctly
--replace_column 1 X 2 X 3 X 4 X 5 X 6 X 7 X 8 X 9 X
EXPLAIN SELECT 1 FROM
  (SELECT 1 FROM t2,t1 WHERE b < c GROUP BY 1 LIMIT 1) AS d2;
DROP TABLE t2;
DROP TABLE t1;

#
# Bug #34773: query with explain extended and derived table / other table
# crashes server
#

CREATE TABLE t1(a INT);
CREATE TABLE t2(a INT);
INSERT INTO t1 VALUES (1),(2);
INSERT INTO t2 VALUES (1),(2);

EXPLAIN EXTENDED SELECT 1
 FROM (SELECT COUNT(DISTINCT t1.a) FROM t1,t2 GROUP BY t1.a) AS s1;

EXPLAIN EXTENDED SELECT 1
 FROM (SELECT COUNT(DISTINCT t1.a) FROM t1,t2 GROUP BY t1.a) AS s1;

prepare s1 from 
'EXPLAIN EXTENDED SELECT 1  
 FROM (SELECT COUNT(DISTINCT t1.a) FROM t1,t2 GROUP BY t1.a) AS s1';
execute s1;

prepare s1 from 
'EXPLAIN EXTENDED SELECT 1  
 FROM (SELECT COUNT(DISTINCT t1.a) FROM t1,t2 GROUP BY t1.a) AS s1';
execute s1;
execute s1;

DROP TABLE t1,t2;


#
# Bug #43354: Use key hint can crash server in explain extended query
#

CREATE TABLE t1 (a INT PRIMARY KEY);

--error ER_KEY_DOES_NOT_EXISTS
EXPLAIN EXTENDED SELECT COUNT(a) FROM t1 USE KEY(a);

DROP TABLE t1;

#
# Bug#45989 memory leak after explain encounters an error in the query
#
CREATE TABLE t1(a LONGTEXT);
INSERT INTO t1 VALUES (repeat('a',@@global.max_allowed_packet));
INSERT INTO t1 VALUES (repeat('b',@@global.max_allowed_packet));
--error ER_BAD_FIELD_ERROR
EXPLAIN SELECT DISTINCT 1 FROM t1,
        (SELECT DISTINCTROW a AS away FROM t1 GROUP BY a WITH ROLLUP) as d1
         WHERE t1.a = d1.a;
DROP TABLE t1;

--echo #
--echo # Bug#48295:
--echo # explain extended crash with subquery and ONLY_FULL_GROUP_BY sql_mode
--echo #

CREATE TABLE t1 (f1 INT not null);

SELECT @@session.sql_mode INTO @old_sql_mode;
SET SESSION sql_mode='ONLY_FULL_GROUP_BY';

# EXPLAIN EXTENDED (with subselect). used to crash. should give NOTICE.
# Before moving max/min optimization to optimize phase this statement
# generated error, but as far as original query do not contain aggregate
# function user should not see error
#  --error ER_MIX_OF_GROUP_FUNC_AND_FIELDS
EXPLAIN EXTENDED SELECT 1 FROM t1
                          WHERE f1 > ALL( SELECT t.f1 FROM t1,t1 AS t );

SET SESSION sql_mode=@old_sql_mode;

DROP TABLE t1;

--echo End of 5.0 tests.

--echo #
--echo # Bug#37870: Usage of uninitialized value caused failed assertion.
--echo #
create table t1 (dt datetime not null, t time not null);
create table t2 (dt datetime not null);
insert into t1 values ('2001-01-01 1:1:1', '1:1:1'),
('2001-01-01 1:1:1', '1:1:1');
insert into t2 values ('2001-01-01 1:1:1'), ('2001-01-01 1:1:1');
SET @save_join_cache_level=@@join_cache_level;
SET join_cache_level=0;
flush tables;
EXPLAIN SELECT OUTR.dt FROM t1 AS OUTR WHERE OUTR.dt IN (SELECT INNR.dt FROM t2 AS INNR WHERE OUTR.dt IS NULL );
flush tables;
SELECT OUTR.dt FROM t1 AS OUTR WHERE OUTR.dt IN (SELECT INNR.dt FROM t2 AS INNR WHERE OUTR.dt IS NULL );
flush tables;
EXPLAIN SELECT OUTR.dt FROM t1 AS OUTR WHERE OUTR.dt IN ( SELECT INNR.dt FROM t2 AS INNR WHERE OUTR.t < '2005-11-13 7:41:31' ); 
flush tables;
SELECT OUTR.dt FROM t1 AS OUTR WHERE OUTR.dt IN ( SELECT INNR.dt FROM t2 AS INNR WHERE OUTR.t < '2005-11-13 7:41:31' );
SET join_cache_level=@save_join_cache_level;
drop tables t1, t2;

--echo #
--echo # Bug#47669: Query showed by EXPLAIN EXTENDED gives different result from original query
--echo #

CREATE TABLE t1 (c int);
INSERT INTO t1 VALUES (NULL);
CREATE TABLE t2 (d int);
INSERT INTO t2 VALUES (NULL), (0);
EXPLAIN EXTENDED SELECT (SELECT 1 FROM t2 WHERE d = c) FROM t1;
DROP TABLE t1, t2;

--echo #
--echo # Bug#30302: Tables that were optimized away are printed in the
--echo #            EXPLAIN EXTENDED warning.
--echo #
create table t1(f1 int);
create table t2(f2 int);
insert into t1 values(1);
insert into t2 values(1),(2);
explain extended select * from t1 where f1=1;
explain extended select * from t1 join t2 on f1=f2 where f1=1;
drop table t1,t2;

--echo #
--echo # Bug #48419: another explain crash..
--echo #
CREATE TABLE t1 (a INT);
CREATE TABLE t2 (b BLOB, KEY b(b(100)));
INSERT INTO t2 VALUES ('1'), ('2'), ('3');

FLUSH TABLES;

EXPLAIN SELECT 1 FROM t1 WHERE a = (SELECT 1 FROM t1 t JOIN t2 WHERE b <= 1 AND t.a);

DROP TABLE t1, t2;

--echo #
--echo # Bug #48573: difference of index selection between rpm binary and
--echo #             .tar.gz, windows vs linux..
--echo #

CREATE TABLE t1(c1 INT, c2 INT, c4 INT, c5 INT, KEY(c2, c5), KEY(c2, c4, c5));
INSERT INTO t1 VALUES(4, 1, 1, 1);
INSERT INTO t1 VALUES(3, 1, 1, 1);
INSERT INTO t1 VALUES(2, 1, 1, 1);
INSERT INTO t1 VALUES(1, 1, 1, 1);
INSERT INTO t1 VALUES(5, 2, 1, 1);
INSERT INTO t1 VALUES(6, 2, 1, 1);
INSERT INTO t1 VALUES(7, 3, 1, 1);
INSERT INTO t1 VALUES(9, 3, 1, 1);
INSERT INTO t1 VALUES(10, 4, 1, 1);
INSERT INTO t1 VALUES(11, 4, 1, 1);

EXPLAIN SELECT c1 FROM t1 WHERE c2 = 1 AND c4 = 1 AND c5 = 1;

DROP TABLE t1;

--echo #
--echo # Bug#56814 Explain + subselect + fulltext crashes server
--echo #

CREATE TABLE t1(f1 VARCHAR(6) NOT NULL,
FULLTEXT KEY(f1),UNIQUE(f1));
INSERT INTO t1 VALUES ('test');

EXPLAIN SELECT 1 FROM t1
WHERE 1 > ALL((SELECT t1.f1 FROM t1 JOIN t1 a ON (MATCH(t1.f1) AGAINST (""))
WHERE t1.f1 GROUP BY t1.f1));

PREPARE stmt FROM
'EXPLAIN SELECT 1 FROM t1
 WHERE 1 > ALL((SELECT t1.f1 FROM t1 RIGHT OUTER JOIN t1 a
 ON (MATCH(t1.f1) AGAINST (""))
 WHERE t1.f1 GROUP BY t1.f1))';

EXECUTE stmt;
EXECUTE stmt;

DEALLOCATE PREPARE stmt;

PREPARE stmt FROM
'EXPLAIN SELECT 1 FROM t1
 WHERE 1 > ALL((SELECT t1.f1 FROM t1 JOIN t1 a
 ON (MATCH(t1.f1) AGAINST (""))
 WHERE t1.f1 GROUP BY t1.f1))';

EXECUTE stmt;
EXECUTE stmt;

DEALLOCATE PREPARE stmt;

DROP TABLE t1;

--echo End of 5.1 tests.

--echo #
--echo # Bug#11829785 EXPLAIN EXTENDED CRASH WITH RIGHT OUTER JOIN, SUBQUERIES
--echo #

CREATE TABLE t1(a INT);

INSERT INTO t1 VALUES (0), (0);

PREPARE s FROM 
'EXPLAIN EXTENDED
SELECT SUBSTRING(1, (SELECT 1 FROM t1 a1 RIGHT OUTER JOIN t1 ON 0)) AS d
FROM t1 WHERE 0 > ANY (SELECT @a FROM t1)';

--error ER_SUBQUERY_NO_1_ROW
EXECUTE s;

DEALLOCATE PREPARE s;
DROP TABLE t1;

--echo #
--echo # Bug#776295: EXPLAIN EXTENDED with always false multiple equality
--echo #             in the WHERE condition of a derived table
--echo #

CREATE TABLE t1 (a int) ;

CREATE TABLE t2 (a int) ;
INSERT INTO t2 VALUES (8);

set @tmp_optimizer_switch=@@optimizer_switch;
set optimizer_switch='derived_merge=off,derived_with_keys=off';
EXPLAIN EXTENDED
SELECT * FROM ( SELECT t1.a FROM t1,t2 WHERE t2.a = t1.a ) AS t;
set optimizer_switch=@tmp_optimizer_switch;

DROP TABLE t1,t2;

--echo #
--echo # MDEV-7215: EXPLAIN REPLACE produces an error:
--echo # Column count doesn't match value count 
--echo #
create table t1 (a int);
insert into t1 values (1);
create table t2 (b int, c int);

replace into t2 select 100, (select a from t1);
explain replace into t2 select 100, (select a from t1);
#analyze replace into t2 select 100, (select a from t1);

drop table t1, t2;

--echo # End of 10.1 tests

--echo #
--echo # End of 10.2 test
--echo #

--echo #
--echo # MDEV-25564: Server crashed on running some EXPLAIN statements
--echo #

EXPLAIN (SELECT 1,3) UNION (SELECT 2,1) ORDER BY (SELECT 2);

--echo #
--echo # MDEV-23160: SIGSEGV in Explain_node::print_explain_for_children on UNION SELECT
--echo #

CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1),(2),(3);

EXPLAIN
SELECT *
FROM t1
WHERE
  a IN (SELECT a FROM t1
        UNION
        SELECT a FROM t1 ORDER BY (SELECT a))
UNION
  SELECT * FROM t1 ORDER BY (SELECT a);
drop table t1;

--disable_ps_protocol
explain
VALUES ( (VALUES (2))) UNION VALUES ( (SELECT 3));
--enable_ps_protocol

--echo #
--echo # End of 10.4 tests
--echo #

CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1),(2);
CREATE TABLE t2 (b INT);
INSERT INTO t2 VALUES (3),(4);

EXPLAIN SELECT * FROM t1, t2 WHERE t2.b IN (SELECT 5 UNION SELECT 6);
EXPLAIN DELETE t2 FROM t1, t2 WHERE t2.b IN (SELECT 5 UNION SELECT 6);
prepare stmt from "EXPLAIN DELETE t2 FROM t1, t2 WHERE t2.b IN (SELECT 5 UNION SELECT 6)";
execute stmt;
execute stmt;

# Cleanup

DROP TABLE t1, t2;

--echo #
--echo # End of 10.5 tests
--echo #