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Merge bk@192.168.21.1:mysql-5.0-opt

Browse source 
into  mysql.com:/d2/hf/opt/my50-opt
This commit is contained in:
unknown 2007-01-09 11:19:17 +04:00
commit e3d81238e4
3 changed files with 100 additions and 2 deletions
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37
mysql-test/r/distinct.result
View file

@ -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;

21
mysql-test/t/distinct.test
View file

@ -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;

44
sql/sql_select.cc
View file

@ -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);