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Derived tables and union can now create distinct keys
The idea is that instead of marking all select_lex's with DISTINCT, we only mark those that really need distinct result. Benefits of this change: - Temporary tables used with derived tables, UNION, IN are now smaller as duplicates are removed already on the insert phase. - The optimizer can now produce better plans with EQ_REF. This can be seen from the tests where several queries does not anymore materialize derived tables twice. - Queries affected by 'in_predicate_conversion_threshold' where large IN lists are converted to sub query produces better plans. Other things: - Removed on duplicate call to sel->init_select() in LEX::add_primary_to_query_expression_body() - I moved the testing of tab->table->pos_in_table_list->is_materialized_derived() in join_read_const_table() to the caller as it caused problems for derived tables that could be proven to be const tables. This also is likely to fix some bugs as if join_read_const_table() was aborted, the table was left marked as JT_CONST, which cannot be good. I added an ASSERT there for now that can be removed when the code has been properly tested.
This commit is contained in:
Monty
Sergei Petrunia
@@ -741,21 +741,19 @@ a b
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explain extended select * from t1
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where a in (values (1));
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 6 100.00
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1 PRIMARY <subquery3> eq_ref distinct_key distinct_key 4 func 1 100.00
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3 MATERIALIZED <derived2> ALL NULL NULL NULL NULL 2 100.00
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1 PRIMARY t1 ALL NULL NULL NULL NULL 6 100.00 Using where
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1 PRIMARY <derived2> eq_ref distinct_key distinct_key 4 test.t1.a 1 100.00
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2 DERIVED NULL NULL NULL NULL NULL NULL NULL NULL No tables used
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Warnings:
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Note 1003 /* select#1 */ select "test"."t1"."a" AS "a","test"."t1"."b" AS "b" from "test"."t1" semi join ((values (1)) "tvc_0") where 1
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Note 1003 /* select#1 */ select "test"."t1"."a" AS "a","test"."t1"."b" AS "b" from (values (1)) "tvc_0" join "test"."t1" where "tvc_0"."1" = "test"."t1"."a"
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explain extended select * from t1
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where a in (select * from (values (1)) as tvc_0);
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 6 100.00
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1 PRIMARY <subquery2> eq_ref distinct_key distinct_key 4 func 1 100.00
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2 MATERIALIZED <derived3> ALL NULL NULL NULL NULL 2 100.00
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1 PRIMARY t1 ALL NULL NULL NULL NULL 6 100.00 Using where
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1 PRIMARY <derived3> eq_ref distinct_key distinct_key 4 test.t1.a 1 100.00
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3 DERIVED NULL NULL NULL NULL NULL NULL NULL NULL No tables used
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Warnings:
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Note 1003 /* select#1 */ select "test"."t1"."a" AS "a","test"."t1"."b" AS "b" from "test"."t1" semi join ((values (1)) "tvc_0") where 1
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Note 1003 /* select#1 */ select "test"."t1"."a" AS "a","test"."t1"."b" AS "b" from (values (1)) "tvc_0" join "test"."t1" where "tvc_0"."1" = "test"."t1"."a"
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# IN-subquery with VALUES structure(s) : UNION with VALUES on the first place
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select * from t1
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where a in (values (1) union select 2);
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@@ -774,7 +772,7 @@ explain extended select * from t1
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where a in (values (1) union select 2);
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 6 100.00 Using where
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4 DEPENDENT SUBQUERY <derived2> ref key0 key0 4 func 2 100.00
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4 DEPENDENT SUBQUERY <derived2> eq_ref distinct_key distinct_key 4 func 1 100.00
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2 DERIVED NULL NULL NULL NULL NULL NULL NULL NULL No tables used
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3 DEPENDENT UNION NULL NULL NULL NULL NULL NULL NULL NULL No tables used
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NULL UNION RESULT <union4,3> ALL NULL NULL NULL NULL NULL NULL
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@@ -785,7 +783,7 @@ where a in (select * from (values (1)) as tvc_0 union
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select 2);
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 6 100.00 Using where
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2 DEPENDENT SUBQUERY <derived3> ref key0 key0 4 func 2 100.00
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2 DEPENDENT SUBQUERY <derived3> eq_ref distinct_key distinct_key 4 func 1 100.00
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3 DERIVED NULL NULL NULL NULL NULL NULL NULL NULL No tables used
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4 DEPENDENT UNION NULL NULL NULL NULL NULL NULL NULL NULL No tables used
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NULL UNION RESULT <union2,4> ALL NULL NULL NULL NULL NULL NULL
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@@ -810,7 +808,7 @@ where a in (select 2 union values (1));
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 6 100.00 Using where
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2 DEPENDENT SUBQUERY NULL NULL NULL NULL NULL NULL NULL NULL No tables used
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4 DEPENDENT UNION <derived3> ref key0 key0 4 func 2 100.00
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4 DEPENDENT UNION <derived3> eq_ref distinct_key distinct_key 4 func 1 100.00
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3 DERIVED NULL NULL NULL NULL NULL NULL NULL NULL No tables used
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NULL UNION RESULT <union2,4> ALL NULL NULL NULL NULL NULL NULL
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Warnings:
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@@ -846,7 +844,7 @@ explain extended select * from t1
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where a in (values (1) union all select b from t1);
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 6 100.00 Using where
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4 DEPENDENT SUBQUERY <derived2> ref key0 key0 4 func 2 100.00
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4 DEPENDENT SUBQUERY <derived2> eq_ref distinct_key distinct_key 4 func 1 100.00
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2 DERIVED NULL NULL NULL NULL NULL NULL NULL NULL No tables used
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3 DEPENDENT UNION t1 ALL NULL NULL NULL NULL 6 100.00 Using where
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Warnings:
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@@ -856,7 +854,7 @@ where a in (select * from (values (1)) as tvc_0 union all
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select b from t1);
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 6 100.00 Using where
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2 DEPENDENT SUBQUERY <derived3> ref key0 key0 4 func 2 100.00
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2 DEPENDENT SUBQUERY <derived3> eq_ref distinct_key distinct_key 4 func 1 100.00
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3 DERIVED NULL NULL NULL NULL NULL NULL NULL NULL No tables used
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4 DEPENDENT UNION t1 ALL NULL NULL NULL NULL 6 100.00 Using where
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Warnings:
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@@ -878,18 +876,18 @@ explain extended select * from t1
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where a not in (values (1),(2));
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 6 100.00 Using where
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3 MATERIALIZED <derived2> ALL NULL NULL NULL NULL 2 100.00
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3 DEPENDENT SUBQUERY <derived2> unique_subquery distinct_key distinct_key 4 func 1 100.00 Using where; Full scan on NULL key
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2 DERIVED NULL NULL NULL NULL NULL NULL NULL NULL No tables used
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Warnings:
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Note 1003 /* select#1 */ select "test"."t1"."a" AS "a","test"."t1"."b" AS "b" from "test"."t1" where !<expr_cache><"test"."t1"."a">(<in_optimizer>("test"."t1"."a","test"."t1"."a" in ( <materialize> (/* select#3 */ select "tvc_0"."1" from (values (1),(2)) "tvc_0" ), <primary_index_lookup>("test"."t1"."a" in <temporary table> on distinct_key where "test"."t1"."a" = "<subquery3>"."1"))))
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Note 1003 /* select#1 */ select "test"."t1"."a" AS "a","test"."t1"."b" AS "b" from "test"."t1" where !<expr_cache><"test"."t1"."a">(<in_optimizer>("test"."t1"."a",<exists>(<primary_index_lookup>(<cache>("test"."t1"."a") in <temporary table> on distinct_key where trigcond(<cache>("test"."t1"."a") = "tvc_0"."1")))))
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explain extended select * from t1
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where a not in (select * from (values (1),(2)) as tvc_0);
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 6 100.00 Using where
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2 MATERIALIZED <derived3> ALL NULL NULL NULL NULL 2 100.00
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2 DEPENDENT SUBQUERY <derived3> unique_subquery distinct_key distinct_key 4 func 1 100.00 Using where; Full scan on NULL key
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3 DERIVED NULL NULL NULL NULL NULL NULL NULL NULL No tables used
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Warnings:
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Note 1003 /* select#1 */ select "test"."t1"."a" AS "a","test"."t1"."b" AS "b" from "test"."t1" where !<expr_cache><"test"."t1"."a">(<in_optimizer>("test"."t1"."a","test"."t1"."a" in ( <materialize> (/* select#2 */ select "tvc_0"."1" from (values (1),(2)) "tvc_0" ), <primary_index_lookup>("test"."t1"."a" in <temporary table> on distinct_key where "test"."t1"."a" = "<subquery2>"."1"))))
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Note 1003 /* select#1 */ select "test"."t1"."a" AS "a","test"."t1"."b" AS "b" from "test"."t1" where !<expr_cache><"test"."t1"."a">(<in_optimizer>("test"."t1"."a",<exists>(<primary_index_lookup>(<cache>("test"."t1"."a") in <temporary table> on distinct_key where trigcond(<cache>("test"."t1"."a") = "tvc_0"."1")))))
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# NOT IN subquery with VALUES structure(s) : UNION with VALUES on the first place
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select * from t1
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where a not in (values (1) union select 2);
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@@ -976,21 +974,19 @@ a b
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explain extended select * from t1
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where a = any (values (1),(2));
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 6 100.00
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1 PRIMARY <subquery3> eq_ref distinct_key distinct_key 4 func 1 100.00
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3 MATERIALIZED <derived2> ALL NULL NULL NULL NULL 2 100.00
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1 PRIMARY t1 ALL NULL NULL NULL NULL 6 100.00 Using where
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1 PRIMARY <derived2> eq_ref distinct_key distinct_key 4 test.t1.a 1 100.00
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2 DERIVED NULL NULL NULL NULL NULL NULL NULL NULL No tables used
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Warnings:
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Note 1003 /* select#1 */ select "test"."t1"."a" AS "a","test"."t1"."b" AS "b" from "test"."t1" semi join ((values (1),(2)) "tvc_0") where 1
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Note 1003 /* select#1 */ select "test"."t1"."a" AS "a","test"."t1"."b" AS "b" from (values (1),(2)) "tvc_0" join "test"."t1" where "tvc_0"."1" = "test"."t1"."a"
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explain extended select * from t1
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where a = any (select * from (values (1),(2)) as tvc_0);
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 6 100.00
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1 PRIMARY <subquery2> eq_ref distinct_key distinct_key 4 func 1 100.00
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2 MATERIALIZED <derived3> ALL NULL NULL NULL NULL 2 100.00
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1 PRIMARY t1 ALL NULL NULL NULL NULL 6 100.00 Using where
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1 PRIMARY <derived3> eq_ref distinct_key distinct_key 4 test.t1.a 1 100.00
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3 DERIVED NULL NULL NULL NULL NULL NULL NULL NULL No tables used
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Warnings:
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Note 1003 /* select#1 */ select "test"."t1"."a" AS "a","test"."t1"."b" AS "b" from "test"."t1" semi join ((values (1),(2)) "tvc_0") where 1
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Note 1003 /* select#1 */ select "test"."t1"."a" AS "a","test"."t1"."b" AS "b" from (values (1),(2)) "tvc_0" join "test"."t1" where "tvc_0"."1" = "test"."t1"."a"
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# ANY-subquery with VALUES structure(s) : UNION with VALUES on the first place
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select * from t1
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where a = any (values (1) union select 2);
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@@ -1009,7 +1005,7 @@ explain extended select * from t1
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where a = any (values (1) union select 2);
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 6 100.00 Using where
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4 DEPENDENT SUBQUERY <derived2> ref key0 key0 4 func 2 100.00
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4 DEPENDENT SUBQUERY <derived2> eq_ref distinct_key distinct_key 4 func 1 100.00
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2 DERIVED NULL NULL NULL NULL NULL NULL NULL NULL No tables used
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3 DEPENDENT UNION NULL NULL NULL NULL NULL NULL NULL NULL No tables used
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NULL UNION RESULT <union4,3> ALL NULL NULL NULL NULL NULL NULL
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@@ -1020,7 +1016,7 @@ where a = any (select * from (values (1)) as tvc_0 union
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select 2);
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 6 100.00 Using where
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2 DEPENDENT SUBQUERY <derived3> ref key0 key0 4 func 2 100.00
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2 DEPENDENT SUBQUERY <derived3> eq_ref distinct_key distinct_key 4 func 1 100.00
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3 DERIVED NULL NULL NULL NULL NULL NULL NULL NULL No tables used
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4 DEPENDENT UNION NULL NULL NULL NULL NULL NULL NULL NULL No tables used
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NULL UNION RESULT <union2,4> ALL NULL NULL NULL NULL NULL NULL
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@@ -1045,7 +1041,7 @@ where a = any (select 2 union values (1));
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 6 100.00 Using where
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2 DEPENDENT SUBQUERY NULL NULL NULL NULL NULL NULL NULL NULL No tables used
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4 DEPENDENT UNION <derived3> ref key0 key0 4 func 2 100.00
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4 DEPENDENT UNION <derived3> eq_ref distinct_key distinct_key 4 func 1 100.00
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3 DERIVED NULL NULL NULL NULL NULL NULL NULL NULL No tables used
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NULL UNION RESULT <union2,4> ALL NULL NULL NULL NULL NULL NULL
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Warnings:
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@@ -1138,7 +1134,7 @@ where a = any (select 1 union values (1));
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 6 100.00 Using where
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2 DEPENDENT SUBQUERY NULL NULL NULL NULL NULL NULL NULL NULL No tables used
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4 DEPENDENT UNION <derived3> ref key0 key0 4 func 2 100.00
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4 DEPENDENT UNION <derived3> eq_ref distinct_key distinct_key 4 func 1 100.00
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3 DERIVED NULL NULL NULL NULL NULL NULL NULL NULL No tables used
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NULL UNION RESULT <union2,4> ALL NULL NULL NULL NULL NULL NULL
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Warnings:
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