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Bug #42760: Select doesn't return desired results when we have null

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values
 
 We should re-set the access method functions when changing the access
 method when switching to another index to avoid sorting.
 
 Fixed by doing a little re-engineering : encapsulating all the function
 assignment into a special function and calling it when flipping the 
 indexes.
This commit is contained in:
Georgi Kodinov 2009-11-10 10:21:41 +02:00
parent 5d725601a8
commit 154c348031
3 changed files with 108 additions and 50 deletions
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21
mysql-test/r/order_by.result
View file

@ -1092,3 +1092,24 @@ FROM t3;
2
NULL
DROP TABLE t1, t2, t3;
#
# Bug #42760: Select doesn't return desired results when we have null
# values
#
CREATE TABLE t1 (
a INT,
c INT,
UNIQUE KEY a_c (a,c),
KEY (a));
INSERT INTO t1 VALUES (1, 10), (2, NULL);
# Must use ref-or-null on the a_c index
EXPLAIN
SELECT 1 AS col FROM t1 WHERE a=2 AND (c=10 OR c IS NULL) ORDER BY c;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref_or_null a_c,a a_c 10 const,const 1 Using where
# Must return 1 row
SELECT 1 AS col FROM t1 WHERE a=2 AND (c=10 OR c IS NULL) ORDER BY c;
col
1
DROP TABLE t1;
End of 5.0 tests

26
mysql-test/t/order_by.test
View file

@ -756,3 +756,29 @@ SELECT
FROM t3;
DROP TABLE t1, t2, t3;
--echo #
--echo # Bug #42760: Select doesn't return desired results when we have null
--echo # values
--echo #
CREATE TABLE t1 (
a INT,
c INT,
UNIQUE KEY a_c (a,c),
KEY (a));
INSERT INTO t1 VALUES (1, 10), (2, NULL);
--echo # Must use ref-or-null on the a_c index
EXPLAIN
SELECT 1 AS col FROM t1 WHERE a=2 AND (c=10 OR c IS NULL) ORDER BY c;
--echo # Must return 1 row
SELECT 1 AS col FROM t1 WHERE a=2 AND (c=10 OR c IS NULL) ORDER BY c;
DROP TABLE t1;
--echo End of 5.0 tests

111
sql/sql_select.cc
View file

@ -6202,6 +6202,56 @@ void rr_unlock_row(st_join_table *tab)
/**
Pick the appropriate access method functions
Sets the functions for the selected table access method
@param tab Table reference to put access method
*/
static void
pick_table_access_method(JOIN_TAB *tab)
{
switch (tab->type)
{
case JT_REF:
tab->read_first_record= join_read_always_key;
tab->read_record.read_record= join_read_next_same;
break;
case JT_REF_OR_NULL:
tab->read_first_record= join_read_always_key_or_null;
tab->read_record.read_record= join_read_next_same_or_null;
break;
case JT_CONST:
tab->read_first_record= join_read_const;
tab->read_record.read_record= join_no_more_records;
break;
case JT_EQ_REF:
tab->read_first_record= join_read_key;
tab->read_record.read_record= join_no_more_records;
break;
case JT_FT:
tab->read_first_record= join_ft_read_first;
tab->read_record.read_record= join_ft_read_next;
break;
case JT_SYSTEM:
tab->read_first_record= join_read_system;
tab->read_record.read_record= join_no_more_records;
break;
/* keep gcc happy */
default:
break;
}
}
static void
make_join_readinfo(JOIN *join, ulonglong options)
{
@ -6234,45 +6284,15 @@ make_join_readinfo(JOIN *join, ulonglong options)
(join->sort_by_table == (TABLE *) 1 && i != join->const_tables)))
ordered_set= 1;
table->status=STATUS_NO_RECORD;
pick_table_access_method (tab);
switch (tab->type) {
case JT_SYSTEM: // Only happens with left join
table->status=STATUS_NO_RECORD;
tab->read_first_record= join_read_system;
tab->read_record.read_record= join_no_more_records;
break;
case JT_CONST: // Only happens with left join
table->status=STATUS_NO_RECORD;
tab->read_first_record= join_read_const;
tab->read_record.read_record= join_no_more_records;
if (table->used_keys.is_set(tab->ref.key) &&
!table->no_keyread)
{
table->key_read=1;
table->file->extra(HA_EXTRA_KEYREAD);
}
break;
case JT_EQ_REF:
table->status=STATUS_NO_RECORD;
if (tab->select)
{
delete tab->select->quick;
tab->select->quick=0;
}
delete tab->quick;
tab->quick=0;
tab->read_first_record= join_read_key;
tab->read_record.unlock_row= join_read_key_unlock_row;
tab->read_record.read_record= join_no_more_records;
if (table->used_keys.is_set(tab->ref.key) &&
!table->no_keyread)
{
table->key_read=1;
table->file->extra(HA_EXTRA_KEYREAD);
}
break;
/* fall through */
case JT_REF_OR_NULL:
case JT_REF:
table->status=STATUS_NO_RECORD;
if (tab->select)
{
delete tab->select->quick;
@ -6280,34 +6300,20 @@ make_join_readinfo(JOIN *join, ulonglong options)
}
delete tab->quick;
tab->quick=0;
/* fall through */
case JT_CONST: // Only happens with left join
if (table->used_keys.is_set(tab->ref.key) &&
!table->no_keyread)
{
table->key_read=1;
table->file->extra(HA_EXTRA_KEYREAD);
}
if (tab->type == JT_REF)
{
tab->read_first_record= join_read_always_key;
tab->read_record.read_record= join_read_next_same;
}
else
{
tab->read_first_record= join_read_always_key_or_null;
tab->read_record.read_record= join_read_next_same_or_null;
}
break;
case JT_FT:
table->status=STATUS_NO_RECORD;
tab->read_first_record= join_ft_read_first;
tab->read_record.read_record= join_ft_read_next;
break;
case JT_ALL:
/*
If previous table use cache
If the incoming data set is already sorted don't use cache.
*/
table->status=STATUS_NO_RECORD;
if (i != join->const_tables && !(options & SELECT_NO_JOIN_CACHE) &&
tab->use_quick != 2 && !tab->first_inner && !ordered_set)
{
@ -6381,6 +6387,9 @@ make_join_readinfo(JOIN *join, ulonglong options)
}
}
break;
case JT_FT:
case JT_SYSTEM:
break;
default:
DBUG_PRINT("error",("Table type %d found",tab->type)); /* purecov: deadcode */
break; /* purecov: deadcode */
@ -12753,6 +12762,8 @@ test_if_skip_sort_order(JOIN_TAB *tab,ORDER *order,ha_rows select_limit,
if (create_ref_for_key(tab->join, tab, keyuse,
tab->join->const_table_map))
DBUG_RETURN(0);
pick_table_access_method(tab);
}
else
{