Merge bk@192.168.21.1:mysql-5.0-opt (e3d81238) · Commits · Software / OSDI20 Artifacts / mariadb

mysql-test/r/distinct.result

+37 −0

Original line number	Diff line number	Diff line
		@@ -607,3 +607,40 @@ id select_type table type possible_keys key key_len ref rows Extra
		SELECT DISTINCT a,a FROM t1 WHERE b < 12 ORDER BY a;
		a a
		DROP TABLE t1;
		CREATE TABLE t1 (a CHAR(1));
		INSERT INTO t1 VALUES('A'), (0);
		SELECT a FROM t1 WHERE a=0;
		a
		A
		0
		Warnings:
		Warning 1292 Truncated incorrect DOUBLE value: 'A'
		SELECT DISTINCT a FROM t1 WHERE a=0;
		a
		A
		0
		Warnings:
		Warning 1292 Truncated incorrect DOUBLE value: 'A'
		DROP TABLE t1;
		CREATE TABLE t1 (a DATE);
		INSERT INTO t1 VALUES ('1972-07-29'), ('1972-02-06');
		EXPLAIN SELECT (SELECT DISTINCT a FROM t1 WHERE a = '2002-08-03');
		id select_type table type possible_keys key key_len ref rows Extra
		1 PRIMARY NULL NULL NULL NULL NULL NULL NULL No tables used
		2 SUBQUERY t1 ALL NULL NULL NULL NULL 2 Using where
		EXPLAIN SELECT (SELECT DISTINCT ADDDATE(a,1) FROM t1
		WHERE ADDDATE(a,1) = '2002-08-03');
		id select_type table type possible_keys key key_len ref rows Extra
		1 PRIMARY NULL NULL NULL NULL NULL NULL NULL No tables used
		2 SUBQUERY t1 ALL NULL NULL NULL NULL 2 Using where; Using temporary
		CREATE TABLE t2 (a CHAR(5) CHARACTER SET latin1 COLLATE latin1_general_ci);
		INSERT INTO t2 VALUES (0xf6);
		INSERT INTO t2 VALUES ('oe');
		SELECT COUNT(*) FROM (SELECT DISTINCT a FROM t2) dt;
		COUNT(*)
		2
		SELECT COUNT(*) FROM
		(SELECT DISTINCT a FROM t2 WHERE a='oe' COLLATE latin1_german2_ci) dt;
		COUNT(*)
		2
		DROP TABLE t1, t2;

mysql-test/t/distinct.test

+21 −0

Original line number	Diff line number	Diff line
		@@ -504,3 +504,24 @@ DROP TABLE t1;
		#DROP TABLE t1;
		#DROP TABLE t2;

		#
		# Bug #15881: cast problems
		#
		CREATE TABLE t1 (a CHAR(1)); INSERT INTO t1 VALUES('A'), (0);
		SELECT a FROM t1 WHERE a=0;
		SELECT DISTINCT a FROM t1 WHERE a=0;
		DROP TABLE t1;
		CREATE TABLE t1 (a DATE);
		INSERT INTO t1 VALUES ('1972-07-29'), ('1972-02-06');
		EXPLAIN SELECT (SELECT DISTINCT a FROM t1 WHERE a = '2002-08-03');
		EXPLAIN SELECT (SELECT DISTINCT ADDDATE(a,1) FROM t1
		WHERE ADDDATE(a,1) = '2002-08-03');
		CREATE TABLE t2 (a CHAR(5) CHARACTER SET latin1 COLLATE latin1_general_ci);
		INSERT INTO t2 VALUES (0xf6);
		INSERT INTO t2 VALUES ('oe');

		SELECT COUNT(*) FROM (SELECT DISTINCT a FROM t2) dt;
		SELECT COUNT(*) FROM
		(SELECT DISTINCT a FROM t2 WHERE a='oe' COLLATE latin1_german2_ci) dt;

		DROP TABLE t1, t2;

sql/sql_select.cc

+42 −2

Original line number	Diff line number	Diff line
		@@ -8432,6 +8432,46 @@ remove_eq_conds(THD thd, COND cond, Item::cond_result *cond_value)
		return cond; // Point at next and level
		}

		/*
		Check if equality can be used in removing components of GROUP BY/DISTINCT

		SYNOPSIS
		test_if_equality_guarantees_uniqueness()
		l the left comparison argument (a field if any)
		r the right comparison argument (a const of any)

		DESCRIPTION
		Checks if an equality predicate can be used to take away
		DISTINCT/GROUP BY because it is known to be true for exactly one
		distinct value (e.g. <expr> == <const>).
		Arguments must be of the same type because e.g.
		<string_field> = <int_const> may match more than 1 distinct value from
		the column.
		We must take into consideration and the optimization done for various
		string constants when compared to dates etc (see Item_int_with_ref) as
		well as the collation of the arguments.

		RETURN VALUE
		TRUE can be used
		FALSE cannot be used
		*/
		static bool
		test_if_equality_guarantees_uniqueness(Item l, Item r)
		{
		return r->const_item() &&
		/* elements must be of the same result type */
		(r->result_type() == l->result_type() \|\|
		/* or dates compared to longs */
		(((l->type() == Item::FIELD_ITEM &&
		((Item_field *)l)->field->can_be_compared_as_longlong()) \|\|
		(l->type() == Item::FUNC_ITEM &&
		((Item_func *)l)->result_as_longlong())) &&
		r->result_type() == INT_RESULT))
		/* and must have the same collation if compared as strings */
		&& (l->result_type() != STRING_RESULT \|\|
		l->collation.collation == r->collation.collation);
		}

		/*
		Return 1 if the item is a const value in all the WHERE clause
		*/
		@@ -8468,7 +8508,7 @@ const_expression_in_where(COND cond, Item comp_item, Item **const_item)
		Item right_item= ((Item_func) cond)->arguments()[1];
		if (left_item->eq(comp_item,1))
		{
		if (right_item->const_item())
		if (test_if_equality_guarantees_uniqueness (left_item, right_item))
		{
		if (*const_item)
		return right_item->eq(*const_item, 1);
		@@ -8478,7 +8518,7 @@ const_expression_in_where(COND cond, Item comp_item, Item **const_item)
		}
		else if (right_item->eq(comp_item,1))
		{
		if (left_item->const_item())
		if (test_if_equality_guarantees_uniqueness (right_item, left_item))
		{
		if (*const_item)
		return left_item->eq(*const_item, 1);