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129 lines
5.8 KiB
Text
129 lines
5.8 KiB
Text
drop table if exists t0, t1;
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create table t0 (a int) engine=myisam;
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insert into t0 values (1),(2),(3),(4),(5),(6),(7),(8);
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#
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# Tests for single-table DELETE
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#
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explain select * from t0 where a=3;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t0 ALL NULL NULL NULL NULL 8 Using where
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explain delete from t0 where a=3;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t0 ALL NULL NULL NULL NULL 8 Using where
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# DELETE without WHERE is a special case:
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explain delete from t0;
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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 Deleting all rows
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create table t1 (a int, b int, filler char(100), key(a), key(b));
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insert into t1
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select A.a+10*B.a + 10*C.a, A.a+10*B.a + 10*C.a, 'filler'
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from t0 A, t0 B, t0 C;
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# This should use an index, possible_keys=NULL because there is no WHERE
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explain delete from t1 order by a limit 2;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 index NULL a NULL NULL 512
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# This should use range, possible_keys={a,b}
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explain delete from t1 where a<20 and b < 10;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 range a,b a 5 NULL 1 Using where
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# This should use ALL + filesort
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explain delete from t1 order by a+1 limit 2;
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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 512 Using filesort
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# This should use range + using filesort
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explain delete from t1 where a<20 order by b limit 2;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 range a a 5 NULL 1 Using where; Using filesort
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# Try some subqueries:
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explain delete from t1 where a < (select max(a) from t0);
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t1 range a a 5 NULL 1 Using where
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2 SUBQUERY t0 ALL NULL NULL NULL NULL 8
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explain delete from t1 where a < (select max(a) from t0 where a < t1.b);
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 512 Using where
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2 DEPENDENT SUBQUERY t0 ALL NULL NULL NULL NULL 8 Using where
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#
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# Tests for multi-table DELETE
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#
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explain delete t1 from t0, t1 where t0.a = t1.a;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t0 ALL NULL NULL NULL NULL 8 Using where
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1 SIMPLE t1 ref a a 5 test.t0.a 4 Using index
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drop table t0, t1;
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# ###################################################################
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# ## EXPLAIN UPDATE tests
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# ###################################################################
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create table t0 (a int) engine=myisam;
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insert into t0 values (1),(2),(3),(4),(5),(6),(7),(8);
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explain update t0 set a=3 where a=4;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t0 ALL NULL NULL NULL NULL 8 Using where
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create table t1 (a int, b int, filler char(100), key(a), key(b));
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insert into t1
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select A.a+10*B.a + 10*C.a, A.a+10*B.a + 10*C.a, 'filler'
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from t0 A, t0 B, t0 C;
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explain update t1 set a=a+1 where 3>4;
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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 Impossible where
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explain update t1 set a=a+1 where a=3 and a=4;
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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 Impossible where
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# This should use an index, possible_keys=NULL because there is no WHERE
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explain update t1 set a=a+1 order by a limit 2;
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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 512
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# This should use range, possible_keys={a,b}
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explain update t1 set filler='fooo' where a<20 and b < 10;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 range a,b a 5 NULL 1 Using where
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# This should use ALL + filesort
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explain update t1 set filler='fooo' order by a+1 limit 2;
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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 512
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# This should use range + using filesort
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explain update t1 set filler='fooo' where a<20 order by b limit 2;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 range a a 5 NULL 1 Using where
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# Try some subqueries:
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explain update t1 set filler='fooo' where a < (select max(a) from t0);
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t1 range a a 5 NULL 1 Using where
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2 SUBQUERY t0 ALL NULL NULL NULL NULL 8
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explain update t1 set filler='fooo' where a < (select max(a) from t0 where a < t1.b);
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 512 Using where
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2 DEPENDENT SUBQUERY t0 ALL NULL NULL NULL NULL 8 Using where
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#
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# Tests for multi-table UPDATE
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#
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explain update t0, t1 set t1.a=t1.a+1 where t0.a = t1.a;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t0 ALL NULL NULL NULL NULL 8 Using where
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1 SIMPLE t1 ref a a 5 test.t0.a 4 Using index
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drop table t0, t1;
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#
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# Try DELETE ... RETURNING ...
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#
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create table t0 (a int);
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insert into t0 values (1),(2),(3),(4);
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explain delete from t0 where a=1 returning a;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t0 ALL NULL NULL NULL NULL 4 Using where
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explain delete from t0 returning a;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t0 ALL NULL NULL NULL NULL 4
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drop table t0;
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#
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# MDEV-5070 - EXPLAIN INSERT ... SELECT crashes on 10.0-base-explain-slowquerylog
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#
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create table t0 (a int);
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insert into t0 values (1),(2),(3),(4),(5),(6),(7),(8);
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create table t1 (a int);
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explain insert into t1 select * from t0;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t0 ALL NULL NULL NULL NULL 8
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explain replace into t1 select * from t0;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t0 ALL NULL NULL NULL NULL 8
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drop table t0, t1;
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