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ff8d4009a7
Undo the change in test_if_skip_sort_order() that set ref_key=-1 when a variant of index_merge is used (was made in fix for MDEV-9021). It turned out that test_if_cheaper_ordering() call below assumes that ref_key=-1 means "no index is used", that is, "an inefficient full table scan is done". This is not the same as index_merge, index_merge can actually be quite efficient. So, ref_key=MAX_KEY denotes the fact that some index is used, not any given index.
51 lines
1.4 KiB
Plaintext
51 lines
1.4 KiB
Plaintext
drop table if exists t0,t1,t2,t3;
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#
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# MDEV-6434: Wrong result (extra rows) with ORDER BY, multiple-column index, InnoDB
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#
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CREATE TABLE t1 (a INT, b INT, c INT, d TEXT, KEY idx(a,b,c)) ENGINE=InnoDB;
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INSERT INTO t1 (a,c) VALUES
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(8, 9),(8, 10),(13, 15),(16, 17),(16, 18),(16, 19),(20, 21),
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(20, 22),(20, 24),(20, 25),(20, 26),(20, 27),(20, 28);
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SELECT * FROM t1 WHERE a = 8 AND (b = 1 OR b IS NULL) ORDER BY c;
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a b c d
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8 NULL 9 NULL
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8 NULL 10 NULL
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DROP TABLE t1;
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#
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# MDEV-9457: Poor query plan chosen for ORDER BY query by a recent 10.1
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#
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create table t0 (a int);
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insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
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create table t1 (
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pk int primary key,
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key1 int,
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key2 int,
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col1 char(255),
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key(key1),
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key(key2)
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) engine=innodb;
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set @a=-1;
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insert into t1
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select
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@a:=@a+1,
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@a,
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@a,
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repeat('abcd', 63)
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from t0 A, t0 B, t0 C, t0 D;
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# The following must NOT use 'index' on PK.
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# It should use index_merge(key1,key2) + filesort
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explain
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select *
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from t1
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where key1<3 or key2<3
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order by pk;
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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_merge key1,key2 key1,key2 5,5 NULL # Using sort_union(key1,key2); Using where; Using filesort
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explain
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select *
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from t1
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where key1<3 or key2<3;
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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_merge key1,key2 key1,key2 5,5 NULL # Using sort_union(key1,key2); Using where
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drop table t0, t1;
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