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bug #27531: 5.1 part of the fix:
- added join cache indication in EXPLAIN (Extra column). - prefer filesort over full scan over index for ORDER BY (because it's faster). - when switching from REF to RANGE because RANGE uses longer key turn off sort on the head table only as the resulting RANGE access is a candidate for join cache and we don't want to disable it by sorting on the first table only. mysql-test/r/archive_gis.result: bug #27531: join cache in EXPLAIN mysql-test/r/compress.result: bug #27531: - join cache in EXPLAIN. - prefer filesort over full scan over index for ORDER BY. mysql-test/r/ctype_utf8.result: bug #27531: join cache in EXPLAIN mysql-test/r/derived.result: bug #27531: join cache in EXPLAIN mysql-test/r/distinct.result: bug #27531: join cache in EXPLAIN mysql-test/r/func_group.result: bug #27531: join cache in EXPLAIN mysql-test/r/func_group_innodb.result: bug #27531: join cache in EXPLAIN mysql-test/r/gis.result: bug #27531: join cache in EXPLAIN mysql-test/r/greedy_optimizer.result: bug #27531: join cache in EXPLAIN mysql-test/r/group_by.result: bug #27531: join cache in EXPLAIN mysql-test/r/group_min_max.result: bug #27531: join cache in EXPLAIN mysql-test/r/index_merge_myisam.result: bug #27531: join cache in EXPLAIN mysql-test/r/information_schema.result: bug #27531: join cache in EXPLAIN mysql-test/r/innodb_gis.result: bug #27531: join cache in EXPLAIN mysql-test/r/innodb_mysql.result: bug #27531: join cache in EXPLAIN mysql-test/r/join.result: bug #27531: join cache in EXPLAIN mysql-test/r/join_nested.result: bug #27531: join cache in EXPLAIN mysql-test/r/key_diff.result: bug #27531: join cache in EXPLAIN mysql-test/r/myisam.result: bug #27531: join cache in EXPLAIN mysql-test/r/ndb_condition_pushdown.result: bug #27531: join cache in EXPLAIN mysql-test/r/ndb_gis.result: bug #27531: join cache in EXPLAIN mysql-test/r/range.result: bug #27531: join cache in EXPLAIN mysql-test/r/row.result: bug #27531: join cache in EXPLAIN mysql-test/r/select.result: bug #27531: - join cache in EXPLAIN. - prefer filesort over full scan over index for ORDER BY. mysql-test/r/ssl.result: bug #27531: - join cache in EXPLAIN. - prefer filesort over full scan over index for ORDER BY. mysql-test/r/ssl_compress.result: bug #27531: - join cache in EXPLAIN. - prefer filesort over full scan over index for ORDER BY. mysql-test/r/subselect.result: bug #27531: join cache in EXPLAIN mysql-test/r/subselect3.result: bug #27531: join cache in EXPLAIN mysql-test/r/union.result: bug #27531: join cache in EXPLAIN mysql-test/r/view.result: bug #27531: join cache in EXPLAIN sql/sql_select.cc: bug #27531: - join cache in EXPLAIN. - prefer filesort over full scan over index for ORDER BY. - disable sorting on the first table only when switching from REF to RANGE.
This commit is contained in:
@ -57,7 +57,7 @@ a b a b
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3 c 3 c
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explain select * from t1 as x1, (select * from t1) as x2;
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY x1 ALL NULL NULL NULL NULL 4
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1 PRIMARY x1 ALL NULL NULL NULL NULL 4 Using join cache
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1 PRIMARY <derived2> ALL NULL NULL NULL NULL 4
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2 DERIVED t1 ALL NULL NULL NULL NULL 4
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drop table if exists t2,t3;
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@ -188,13 +188,13 @@ pla_id test
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105 3
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explain SELECT STRAIGHT_JOIN d.pla_id, m2.mat_id FROM t1 m2 INNER JOIN (SELECT mp.pla_id, MIN(m1.matintnum) AS matintnum FROM t2 mp INNER JOIN t1 m1 ON mp.mat_id=m1.mat_id GROUP BY mp.pla_id) d ON d.matintnum=m2.matintnum;
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY m2 ALL NULL NULL NULL NULL 9
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1 PRIMARY m2 ALL NULL NULL NULL NULL 9 Using join cache
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1 PRIMARY <derived2> ALL NULL NULL NULL NULL 6 Using where
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2 DERIVED mp ALL NULL NULL NULL NULL 9 Using temporary; Using filesort
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2 DERIVED m1 eq_ref PRIMARY PRIMARY 3 test.mp.mat_id 1
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explain SELECT STRAIGHT_JOIN d.pla_id, m2.test FROM t1 m2 INNER JOIN (SELECT mp.pla_id, MIN(m1.matintnum) AS matintnum FROM t2 mp INNER JOIN t1 m1 ON mp.mat_id=m1.mat_id GROUP BY mp.pla_id) d ON d.matintnum=m2.matintnum;
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY m2 ALL NULL NULL NULL NULL 9
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1 PRIMARY m2 ALL NULL NULL NULL NULL 9 Using join cache
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1 PRIMARY <derived2> ALL NULL NULL NULL NULL 6 Using where
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2 DERIVED mp ALL NULL NULL NULL NULL 9 Using temporary; Using filesort
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2 DERIVED m1 eq_ref PRIMARY PRIMARY 3 test.mp.mat_id 1
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@ -245,7 +245,7 @@ a a
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2 2
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explain select * from ( select * from t1 union select * from t1) a,(select * from t1 union select * from 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 <derived2> ALL NULL NULL NULL NULL 2
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1 PRIMARY <derived2> ALL NULL NULL NULL NULL 2 Using join cache
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1 PRIMARY <derived4> ALL NULL NULL NULL NULL 2
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4 DERIVED t1 ALL NULL NULL NULL NULL 2
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5 UNION t1 ALL NULL NULL NULL NULL 2
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@ -312,7 +312,7 @@ b 3.5000
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explain SELECT s.name, AVG(s.val) AS median FROM (SELECT x.name, x.val FROM t1 x, t1 y WHERE x.name=y.name GROUP BY x.name, x.val HAVING SUM(y.val <= x.val) >= COUNT(*)/2 AND SUM(y.val >= x.val) >= COUNT(*)/2) AS s GROUP BY s.name;
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY <derived2> ALL NULL NULL NULL NULL 3 Using temporary; Using filesort
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2 DERIVED x ALL NULL NULL NULL NULL 17 Using temporary; Using filesort
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2 DERIVED x ALL NULL NULL NULL NULL 17 Using temporary; Using filesort; Using join cache
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2 DERIVED y ALL NULL NULL NULL NULL 17 Using where
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drop table t1;
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create table t2 (a int, b int, primary key (a));
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