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c2cb9b97be
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
53 lines
777 B
Plaintext
53 lines
777 B
Plaintext
drop table if exists t1;
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CREATE TABLE t1 (
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a char(5) NOT NULL,
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b char(4) NOT NULL,
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KEY (a),
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KEY (b)
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);
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INSERT INTO t1 VALUES ('A','B'),('b','A'),('C','c'),('D','E'),('a','a');
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select * from t1,t1 as t2;
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a b a b
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A B A B
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b A A B
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C c A B
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D E A B
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a a A B
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A B b A
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b A b A
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C c b A
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D E b A
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a a b A
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A B C c
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b A C c
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C c C c
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D E C c
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a a C c
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A B D E
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b A D E
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C c D E
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D E D E
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a a D E
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A B a a
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b A a a
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C c a a
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D E a a
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a a a a
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explain select t1.*,t2.* from t1,t1 as t2 where t1.A=t2.B;
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table type possible_keys key key_len ref rows Extra
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t1 ALL a NULL NULL NULL 5
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t2 ALL b NULL NULL NULL 4 Using where
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select t1.*,t2.* from t1,t1 as t2 where t1.A=t2.B order by binary t1.a,t2.a;
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a b a b
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A B a a
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A B b A
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C c C c
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a a a a
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a a b A
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b A A B
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select * from t1 where a='a';
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a b
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A B
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a a
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drop table t1;
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