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Added thread variable max_seeks_for_key
Change optimizer to prefer key lookups before table scan Change table scans to be done after tables with constrains on scanned table mysql-test/r/distinct.result: Update results mysql-test/r/group_by.result: Update results mysql-test/r/heap.result: Update results mysql-test/r/join.result: Update results mysql-test/r/key_diff.result: Update results mysql-test/r/myisam.result: Update results mysql-test/r/order_by.result: Update results mysql-test/r/select_safe.result: Update results mysql-test/t/distinct.test: Change test to be repeatable mysql-test/t/join.test: Change test to be repeatable mysql-test/t/select_safe.test: Add tests for MAX_SEEKS_FOR_KEY sql/handler.h: Optimize structure for 64 bit machines (and to avoid problems with gdb) sql/item_cmpfunc.cc: Initialize not_null_tables_cache properly sql/mysqld.cc: Added max_seeks_for_key sql/set_var.cc: Added max_seeks_for_key sql/sql_class.h: Added max_seeks_for_key sql/sql_select.cc: Added max_seeks_for_key Change optimizer to prefer key lookups before table scan. Change table scans to be done after tables with constrains on scanned table
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@ -161,7 +161,7 @@ SELECT DISTINCT UserId FROM t1 WHERE UserId=22;
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UserId
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drop table t1;
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CREATE TABLE t1 (a int(10) unsigned not null primary key,b int(10) unsigned);
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INSERT INTO t1 VALUES (1,1),(2,1);
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INSERT INTO t1 VALUES (1,1),(2,1),(3,1),(4,1);
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CREATE TABLE t2 (a int(10) unsigned not null, key (A));
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INSERT INTO t2 VALUES (1),(2);
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CREATE TABLE t3 (a int(10) unsigned, key(A), b text);
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@ -189,7 +189,7 @@ insert into t4 select * from t3;
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insert into t3 select * from t4;
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explain select distinct t1.a from t1,t3 where t1.a=t3.a;
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table type possible_keys key key_len ref rows Extra
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t1 index PRIMARY PRIMARY 4 NULL 2 Using index; Using temporary
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t1 index PRIMARY PRIMARY 4 NULL 4 Using index; Using temporary
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t3 ref a a 5 t1.a 10 Using where; Using index; Distinct
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select distinct t1.a from t1,t3 where t1.a=t3.a;
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a
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@ -200,16 +200,16 @@ select distinct 1 from t1,t3 where t1.a=t3.a;
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1
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explain SELECT distinct t1.a from t1;
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table type possible_keys key key_len ref rows Extra
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t1 index NULL PRIMARY 4 NULL 2 Using index
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t1 index NULL PRIMARY 4 NULL 4 Using index
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explain SELECT distinct t1.a from t1 order by a desc;
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table type possible_keys key key_len ref rows Extra
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t1 index NULL PRIMARY 4 NULL 2 Using index
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t1 index NULL PRIMARY 4 NULL 4 Using index
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explain SELECT t1.a from t1 group by a order by a desc;
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table type possible_keys key key_len ref rows Extra
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t1 index NULL PRIMARY 4 NULL 2 Using index
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t1 index NULL PRIMARY 4 NULL 4 Using index
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explain SELECT distinct t1.a from t1 order by a desc limit 1;
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table type possible_keys key key_len ref rows Extra
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t1 index NULL PRIMARY 4 NULL 2 Using index
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t1 index NULL PRIMARY 4 NULL 4 Using index
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explain SELECT distinct a from t3 order by a desc limit 2;
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table type possible_keys key key_len ref rows Extra
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t3 index NULL a 5 NULL 204 Using index
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