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drop table if exists t1;
create table t1 (nr int(5) not null auto_increment,b blob,str char(10), primary key (nr));
select count(*) from t1;
count(*)
0
select * from t1;
nr b str
select * from t1 limit 0;
nr b str
show status like "Empty_queries";
Variable_name Value
Empty_queries 2
drop table t1;
select * from t2;
ERROR 42S02: Table 'test.t2' doesn't exist
show status like "Empty_queries";
Variable_name Value
Empty_queries 2
# End of 4.1 tests
#
# MDEV-30333 Wrong result with not_null_range_scan and LEFT JOIN with empty table
#
set @save_optimizer_switch=@@optimizer_switch;
CREATE TABLE t1 (a INT, b INT) ENGINE=MyISAM;
INSERT INTO t1 (b) VALUES (1),(2);
CREATE TABLE t2 (c INT) ENGINE=MyISAM;
SET optimizer_switch= 'not_null_range_scan=off';
explain extended SELECT b FROM t1 LEFT JOIN t2 ON t2.c = a WHERE a IS NULL ORDER BY b;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 system NULL NULL NULL NULL 0 0.00 Const row not found
1 SIMPLE t1 ALL NULL NULL NULL NULL 2 100.00 Using where; Using filesort
Warnings:
Note 1003 select `test`.`t1`.`b` AS `b` from `test`.`t1` where `test`.`t1`.`a` is null order by `test`.`t1`.`b`
SELECT b FROM t1 LEFT JOIN t2 ON t2.c = a WHERE a IS NULL ORDER BY b;
b
1
2
SET optimizer_switch = 'not_null_range_scan=on';
explain extended SELECT b FROM t1 LEFT JOIN t2 ON t2.c = a WHERE a IS NULL ORDER BY b;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 system NULL NULL NULL NULL 0 0.00 Const row not found
1 SIMPLE t1 ALL NULL NULL NULL NULL 2 100.00 Using where; Using filesort
Warnings:
Note 1003 select `test`.`t1`.`b` AS `b` from `test`.`t1` where `test`.`t1`.`a` is null order by `test`.`t1`.`b`
SELECT b FROM t1 LEFT JOIN t2 ON t2.c = a WHERE a IS NULL ORDER BY b;
b
1
2
flush tables;
SELECT b FROM t1 LEFT JOIN t2 ON t2.c = a WHERE a IS NULL ORDER BY b;
b
1
2
drop table t1,t2;
# Second test in MDEV-30333
CREATE TABLE t1 (a int, b varchar(10)) ENGINE=MyISAM;
INSERT INTO t1 VALUES (69,'foo'),(71,'bar');
CREATE TABLE t2 (c int) ENGINE=MyISAM;
INSERT INTO t2 VALUES (1),(2);
CREATE TABLE t3 (d int, e int, KEY(e)) ENGINE=MyISAM;
SELECT * FROM t1 LEFT JOIN t2 LEFT JOIN t3 ON t3.e = t3.d ON 1;
a b c d e
69 foo 1 NULL NULL
71 bar 1 NULL NULL
69 foo 2 NULL NULL
71 bar 2 NULL NULL
SET optimizer_switch = 'not_null_range_scan=on';
SELECT * FROM t1 LEFT JOIN t2 LEFT JOIN t3 ON t3.e = t3.d ON 1;
a b c d e
69 foo 1 NULL NULL
71 bar 1 NULL NULL
69 foo 2 NULL NULL
71 bar 2 NULL NULL
DROP TABLE t1, t2, t3;
set @@optimizer_switch=@save_optimizer_switch;
End of 10.5 tests
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