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96e092dc73
WL#2474 "Multi Range Read: Change the default MRR implementation to implement new MRR interface"
WL#2475 "Batched range read functions for MyISAM/InnoDb"
"Index condition pushdown for MyISAM/InnoDB"
Igor's fix from sp1r-igor@olga.mysql.com-20080330055902-07614:
There could be observed the following problems:
1. EXPLAIN did not mention pushdown conditions from on expressions in the
'extra' column. As a result if a query had no where conditions pushed
down to a table, but had on conditions pushed to this table the 'extra'
column in the EXPLAIN for the table missed 'using where'.
2. Conditions for ref access were not eliminated from on expressions
though such conditions were eliminated from the where condition.
190 lines
8.8 KiB
Plaintext
190 lines
8.8 KiB
Plaintext
drop table if exists t1;
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create table t1 (id int not null, str char(10), unique(str));
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explain select * from t1;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 system NULL NULL NULL NULL 0 const row not found
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insert into t1 values (1, null),(2, null),(3, "foo"),(4, "bar");
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select * from t1 where str is null;
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id str
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1 NULL
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2 NULL
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select * from t1 where str="foo";
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id str
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3 foo
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explain select * from t1 where str is null;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 ref str str 11 const 1 Using index condition
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explain select * from t1 where str="foo";
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 const str str 11 const 1
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explain select * from t1 ignore key (str) where str="foo";
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 ALL NULL NULL NULL NULL 4 Using where
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explain select * from t1 use key (str,str) where str="foo";
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 const str str 11 const 1
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explain select * from t1 use key (str,str,foo) where str="foo";
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ERROR 42000: Key 'foo' doesn't exist in table 't1'
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explain select * from t1 ignore key (str,str,foo) where str="foo";
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ERROR 42000: Key 'foo' doesn't exist in table 't1'
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drop table t1;
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explain select 1;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE NULL NULL NULL NULL NULL NULL NULL No tables used
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create table t1 (a int not null);
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explain select count(*) from t1;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Select tables optimized away
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insert into t1 values(1);
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explain select count(*) from t1;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Select tables optimized away
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insert into t1 values(1);
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explain select count(*) from t1;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Select tables optimized away
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drop table t1;
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set names koi8r;
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create table <20><><EFBFBD> (<28><><EFBFBD>0 int, <20><><EFBFBD>1 int, key <20><><EFBFBD>0 (<28><><EFBFBD>0), key <20><><EFBFBD>01 (<28><><EFBFBD>0,<2C><><EFBFBD>1));
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insert into <20><><EFBFBD> (<28><><EFBFBD>0) values (1);
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insert into <20><><EFBFBD> (<28><><EFBFBD>0) values (2);
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explain select <20><><EFBFBD>0 from <20><><EFBFBD> where <20><><EFBFBD>0=1;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE <09><><EFBFBD> ref <09><><EFBFBD>0,<2C><><EFBFBD>01 <09><><EFBFBD>0 5 const 1 Using index
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drop table <20><><EFBFBD>;
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set names latin1;
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select 3 into @v1;
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explain select 3 into @v1;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE NULL NULL NULL NULL NULL NULL NULL No tables used
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create table t1(f1 int, f2 int);
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insert into t1 values (1,1);
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create view v1 as select * from t1 where f1=1;
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explain extended select * from v1 where f2=1;
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 SIMPLE t1 system NULL NULL NULL NULL 1 100.00
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Warnings:
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Note 1003 select '1' AS `f1`,'1' AS `f2` from `test`.`t1` where 1
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explain extended select * from t1 where 0;
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 SIMPLE NULL NULL NULL NULL NULL NULL NULL NULL Impossible WHERE
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Warnings:
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Note 1003 select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f2` AS `f2` from `test`.`t1` where 0
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explain extended select * from t1 where 1;
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 SIMPLE t1 system NULL NULL NULL NULL 1 100.00
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Warnings:
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Note 1003 select '1' AS `f1`,'1' AS `f2` from `test`.`t1` where 1
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explain extended select * from t1 having 0;
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 SIMPLE NULL NULL NULL NULL NULL NULL NULL NULL Impossible HAVING
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Warnings:
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Note 1003 select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f2` AS `f2` from `test`.`t1` having 0
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explain extended select * from t1 having 1;
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 SIMPLE t1 system NULL NULL NULL NULL 1 100.00
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Warnings:
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Note 1003 select '1' AS `f1`,'1' AS `f2` from `test`.`t1` having 1
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drop view v1;
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drop table t1;
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CREATE TABLE t1(c INT);
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INSERT INTO t1 VALUES (),();
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CREATE TABLE t2 (b INT,
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KEY(b),KEY(b),KEY(b),KEY(b),KEY(b),
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KEY(b),KEY(b),KEY(b),KEY(b),KEY(b),
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KEY(b),KEY(b),KEY(b),KEY(b),KEY(b),
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KEY(b),KEY(b),KEY(b),KEY(b),KEY(b),
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KEY(b),KEY(b),KEY(b),KEY(b),KEY(b),
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KEY(b),KEY(b),KEY(b),KEY(b),KEY(b),
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KEY(b),KEY(b),KEY(b),KEY(b),KEY(b),
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KEY(b),KEY(b),KEY(b),KEY(b),KEY(b));
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INSERT INTO t2 VALUES (),(),();
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EXPLAIN SELECT 1 FROM
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(SELECT 1 FROM t2,t1 WHERE b < c GROUP BY 1 LIMIT 1) AS d2;
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id select_type table type possible_keys key key_len ref rows Extra
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X X X X X X X X X const row not found
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X X X X X X X X X
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X X X X X X X X X Range checked for each record (index map: 0xFFFFFFFFFF)
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DROP TABLE t2;
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DROP TABLE t1;
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CREATE TABLE t1(a INT);
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CREATE TABLE t2(a INT);
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INSERT INTO t1 VALUES (1),(2);
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INSERT INTO t2 VALUES (1),(2);
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EXPLAIN EXTENDED SELECT 1
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FROM (SELECT COUNT(DISTINCT t1.a) FROM t1,t2 GROUP BY t1.a) AS s1;
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY <derived2> ALL NULL NULL NULL NULL 2 100.00
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2 DERIVED t1 ALL NULL NULL NULL NULL 2 100.00 Using temporary; Using filesort
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2 DERIVED t2 ALL NULL NULL NULL NULL 2 100.00 Using join buffer
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Warnings:
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Note 1003 select 1 AS `1` from (select count(distinct `test`.`t1`.`a`) AS `COUNT(DISTINCT t1.a)` from `test`.`t1` join `test`.`t2` group by `test`.`t1`.`a`) `s1`
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EXPLAIN EXTENDED SELECT 1
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FROM (SELECT COUNT(DISTINCT t1.a) FROM t1,t2 GROUP BY t1.a) AS s1;
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY <derived2> ALL NULL NULL NULL NULL 2 100.00
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2 DERIVED t1 ALL NULL NULL NULL NULL 2 100.00 Using temporary; Using filesort
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2 DERIVED t2 ALL NULL NULL NULL NULL 2 100.00 Using join buffer
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Warnings:
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Note 1003 select 1 AS `1` from (select count(distinct `test`.`t1`.`a`) AS `COUNT(DISTINCT t1.a)` from `test`.`t1` join `test`.`t2` group by `test`.`t1`.`a`) `s1`
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prepare s1 from
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'EXPLAIN EXTENDED SELECT 1
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FROM (SELECT COUNT(DISTINCT t1.a) FROM t1,t2 GROUP BY t1.a) AS s1';
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execute s1;
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY <derived2> ALL NULL NULL NULL NULL 2 100.00
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2 DERIVED t1 ALL NULL NULL NULL NULL 2 100.00 Using temporary; Using filesort
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2 DERIVED t2 ALL NULL NULL NULL NULL 2 100.00 Using join buffer
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Warnings:
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Note 1003 select 1 AS `1` from (select count(distinct `test`.`t1`.`a`) AS `COUNT(DISTINCT t1.a)` from `test`.`t1` join `test`.`t2` group by `test`.`t1`.`a`) `s1`
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prepare s1 from
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'EXPLAIN EXTENDED SELECT 1
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FROM (SELECT COUNT(DISTINCT t1.a) FROM t1,t2 GROUP BY t1.a) AS s1';
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execute s1;
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY <derived2> ALL NULL NULL NULL NULL 2 100.00
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2 DERIVED t1 ALL NULL NULL NULL NULL 2 100.00 Using temporary; Using filesort
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2 DERIVED t2 ALL NULL NULL NULL NULL 2 100.00 Using join buffer
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Warnings:
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Note 1003 select 1 AS `1` from (select count(distinct `test`.`t1`.`a`) AS `COUNT(DISTINCT t1.a)` from `test`.`t1` join `test`.`t2` group by `test`.`t1`.`a`) `s1`
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execute s1;
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY <derived2> ALL NULL NULL NULL NULL 2 100.00
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2 DERIVED t1 ALL NULL NULL NULL NULL 2 100.00 Using temporary; Using filesort
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2 DERIVED t2 ALL NULL NULL NULL NULL 2 100.00 Using join buffer
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Warnings:
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Note 1003 select 1 AS `1` from (select count(distinct `test`.`t1`.`a`) AS `COUNT(DISTINCT t1.a)` from `test`.`t1` join `test`.`t2` group by `test`.`t1`.`a`) `s1`
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DROP TABLE t1,t2;
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CREATE TABLE t1 (a INT PRIMARY KEY);
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EXPLAIN EXTENDED SELECT COUNT(a) FROM t1 USE KEY(a);
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ERROR 42000: Key 'a' doesn't exist in table 't1'
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DROP TABLE t1;
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#
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# Bug#37870: Usage of uninitialized value caused failed assertion.
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#
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create table t1 (dt datetime not null, t time not null);
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create table t2 (dt datetime not null);
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insert into t1 values ('2001-01-01 1:1:1', '1:1:1'),
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('2001-01-01 1:1:1', '1:1:1');
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insert into t2 values ('2001-01-01 1:1:1'), ('2001-01-01 1:1:1');
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flush tables;
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EXPLAIN SELECT OUTR.dt FROM t1 AS OUTR WHERE OUTR.dt IN (SELECT INNR.dt FROM t2 AS INNR WHERE OUTR.dt IS NULL );
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY OUTR ALL NULL NULL NULL NULL 2 Using where
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2 DEPENDENT SUBQUERY INNR ALL NULL NULL NULL NULL 2 Using where
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flush tables;
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SELECT OUTR.dt FROM t1 AS OUTR WHERE OUTR.dt IN (SELECT INNR.dt FROM t2 AS INNR WHERE OUTR.dt IS NULL );
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dt
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flush tables;
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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' );
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY OUTR ALL NULL NULL NULL NULL 2 Using where
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2 DEPENDENT SUBQUERY INNR ALL NULL NULL NULL NULL 2 Using where
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flush tables;
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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' );
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dt
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2001-01-01 01:01:01
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2001-01-01 01:01:01
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drop tables t1, t2;
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End of 5.1 tests.
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