Commit 7cb79671 authored by Martin Hansson's avatar Martin Hansson

Bug#47762: Incorrect result from MIN() when WHERE tests NOT

NULL column for NULL

The optimization to read MIN() and MAX() values from an
index did not properly handle comparisons with NULL
values. Fixed by giving up the particular optimization step
if there are non-NULL safe comparisons with NULL values, as 
the result is NULL anyway.

Also, Oracle copyright notice was added to all files.
parent 7dca134c
--replace_column 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a = NULL;
SELECT MIN( a ) FROM t1 WHERE a = NULL;
--replace_column 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a <> NULL;
SELECT MIN( a ) FROM t1 WHERE a <> NULL;
--replace_column 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a > NULL;
SELECT MIN( a ) FROM t1 WHERE a > NULL;
--replace_column 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a < NULL;
SELECT MIN( a ) FROM t1 WHERE a < NULL;
--replace_column 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a <=> NULL;
SELECT MIN( a ) FROM t1 WHERE a <=> NULL;
--replace_column 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a BETWEEN NULL AND 10;
SELECT MIN( a ) FROM t1 WHERE a BETWEEN NULL AND 10;
--replace_column 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a BETWEEN NULL AND NULL;
SELECT MIN( a ) FROM t1 WHERE a BETWEEN NULL AND NULL;
--replace_column 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a BETWEEN 10 AND NULL;
SELECT MIN( a ) FROM t1 WHERE a BETWEEN 10 AND NULL;
--replace_column 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a = (SELECT a FROM t1 WHERE a < 0);
SELECT MIN( a ) FROM t1 WHERE a = (SELECT a FROM t1 WHERE a < 0);
--replace_column 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a IS NULL;
SELECT MIN( a ) FROM t1 WHERE a IS NULL;
......@@ -2537,4 +2537,230 @@ a
1
2
DROP TABLE t1;
#
# Bug#47762: Incorrect result from MIN() when WHERE tests NOT NULL column
# for NULL
#
## Test for NULLs allowed
CREATE TABLE t1 ( a INT, KEY (a) );
INSERT INTO t1 VALUES (1), (2), (3);
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a = NULL;
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x Impossible WHERE noticed after reading const tables
SELECT MIN( a ) FROM t1 WHERE a = NULL;
MIN( a )
NULL
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a <> NULL;
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x Impossible WHERE noticed after reading const tables
SELECT MIN( a ) FROM t1 WHERE a <> NULL;
MIN( a )
NULL
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a > NULL;
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x Impossible WHERE noticed after reading const tables
SELECT MIN( a ) FROM t1 WHERE a > NULL;
MIN( a )
NULL
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a < NULL;
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x Impossible WHERE noticed after reading const tables
SELECT MIN( a ) FROM t1 WHERE a < NULL;
MIN( a )
NULL
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a <=> NULL;
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x No matching min/max row
SELECT MIN( a ) FROM t1 WHERE a <=> NULL;
MIN( a )
NULL
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a BETWEEN NULL AND 10;
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x Impossible WHERE noticed after reading const tables
SELECT MIN( a ) FROM t1 WHERE a BETWEEN NULL AND 10;
MIN( a )
NULL
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a BETWEEN NULL AND NULL;
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x Impossible WHERE noticed after reading const tables
SELECT MIN( a ) FROM t1 WHERE a BETWEEN NULL AND NULL;
MIN( a )
NULL
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a BETWEEN 10 AND NULL;
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x Impossible WHERE noticed after reading const tables
SELECT MIN( a ) FROM t1 WHERE a BETWEEN 10 AND NULL;
MIN( a )
NULL
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a = (SELECT a FROM t1 WHERE a < 0);
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x Impossible WHERE noticed after reading const tables
x x x x x x x x x Using where; Using index
SELECT MIN( a ) FROM t1 WHERE a = (SELECT a FROM t1 WHERE a < 0);
MIN( a )
NULL
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a IS NULL;
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x No matching min/max row
SELECT MIN( a ) FROM t1 WHERE a IS NULL;
MIN( a )
NULL
INSERT INTO t1 VALUES (NULL), (NULL);
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a = NULL;
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x Impossible WHERE noticed after reading const tables
SELECT MIN( a ) FROM t1 WHERE a = NULL;
MIN( a )
NULL
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a <> NULL;
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x Impossible WHERE noticed after reading const tables
SELECT MIN( a ) FROM t1 WHERE a <> NULL;
MIN( a )
NULL
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a > NULL;
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x Impossible WHERE noticed after reading const tables
SELECT MIN( a ) FROM t1 WHERE a > NULL;
MIN( a )
NULL
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a < NULL;
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x Impossible WHERE noticed after reading const tables
SELECT MIN( a ) FROM t1 WHERE a < NULL;
MIN( a )
NULL
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a <=> NULL;
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x Select tables optimized away
SELECT MIN( a ) FROM t1 WHERE a <=> NULL;
MIN( a )
NULL
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a BETWEEN NULL AND 10;
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x Impossible WHERE noticed after reading const tables
SELECT MIN( a ) FROM t1 WHERE a BETWEEN NULL AND 10;
MIN( a )
NULL
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a BETWEEN NULL AND NULL;
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x Impossible WHERE noticed after reading const tables
SELECT MIN( a ) FROM t1 WHERE a BETWEEN NULL AND NULL;
MIN( a )
NULL
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a BETWEEN 10 AND NULL;
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x Impossible WHERE noticed after reading const tables
SELECT MIN( a ) FROM t1 WHERE a BETWEEN 10 AND NULL;
MIN( a )
NULL
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a = (SELECT a FROM t1 WHERE a < 0);
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x Impossible WHERE noticed after reading const tables
x x x x x x x x x Using where; Using index
SELECT MIN( a ) FROM t1 WHERE a = (SELECT a FROM t1 WHERE a < 0);
MIN( a )
NULL
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a IS NULL;
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x Select tables optimized away
SELECT MIN( a ) FROM t1 WHERE a IS NULL;
MIN( a )
NULL
DROP TABLE t1;
## Test for NOT NULLs
CREATE TABLE t1 ( a INT NOT NULL PRIMARY KEY);
INSERT INTO t1 VALUES (1), (2), (3);
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a = NULL;
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x Impossible WHERE noticed after reading const tables
SELECT MIN( a ) FROM t1 WHERE a = NULL;
MIN( a )
NULL
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a <> NULL;
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x Impossible WHERE noticed after reading const tables
SELECT MIN( a ) FROM t1 WHERE a <> NULL;
MIN( a )
NULL
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a > NULL;
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x Impossible WHERE noticed after reading const tables
SELECT MIN( a ) FROM t1 WHERE a > NULL;
MIN( a )
NULL
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a < NULL;
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x Impossible WHERE noticed after reading const tables
SELECT MIN( a ) FROM t1 WHERE a < NULL;
MIN( a )
NULL
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a <=> NULL;
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x No matching min/max row
SELECT MIN( a ) FROM t1 WHERE a <=> NULL;
MIN( a )
NULL
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a BETWEEN NULL AND 10;
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x Impossible WHERE noticed after reading const tables
SELECT MIN( a ) FROM t1 WHERE a BETWEEN NULL AND 10;
MIN( a )
NULL
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a BETWEEN NULL AND NULL;
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x Impossible WHERE noticed after reading const tables
SELECT MIN( a ) FROM t1 WHERE a BETWEEN NULL AND NULL;
MIN( a )
NULL
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a BETWEEN 10 AND NULL;
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x Impossible WHERE noticed after reading const tables
SELECT MIN( a ) FROM t1 WHERE a BETWEEN 10 AND NULL;
MIN( a )
NULL
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a = (SELECT a FROM t1 WHERE a < 0);
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x Impossible WHERE noticed after reading const tables
x x x x x x x x x Using where; Using index
SELECT MIN( a ) FROM t1 WHERE a = (SELECT a FROM t1 WHERE a < 0);
MIN( a )
NULL
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a IS NULL;
id select_type table type possible_keys key key_len ref rows Extra
x x x x x x x x x Impossible WHERE
SELECT MIN( a ) FROM t1 WHERE a IS NULL;
MIN( a )
NULL
DROP TABLE t1;
End of 5.1 tests
......@@ -1054,4 +1054,23 @@ SELECT 1 AS c, b FROM t1 WHERE b IN (1,2) GROUP BY c, b;
SELECT a FROM t1 WHERE b=1;
DROP TABLE t1;
--echo #
--echo # Bug#47762: Incorrect result from MIN() when WHERE tests NOT NULL column
--echo # for NULL
--echo #
--echo ## Test for NULLs allowed
CREATE TABLE t1 ( a INT, KEY (a) );
INSERT INTO t1 VALUES (1), (2), (3);
--source include/min_null_cond.inc
INSERT INTO t1 VALUES (NULL), (NULL);
--source include/min_null_cond.inc
DROP TABLE t1;
--echo ## Test for NOT NULLs
CREATE TABLE t1 ( a INT NOT NULL PRIMARY KEY);
INSERT INTO t1 VALUES (1), (2), (3);
--source include/min_null_cond.inc
DROP TABLE t1;
--echo End of 5.1 tests
/* Copyright 2000-2008 MySQL AB, 2008, 2009 Sun Microsystems, Inc.
/* Copyright (c) 2000, 2010 Oracle and/or its affiliates. All rights reserved.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
......@@ -11,7 +11,7 @@
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
/*
Because of the function new_field() all field classes that have static
......@@ -55,7 +55,11 @@ class Field
static void operator delete(void *ptr_arg, size_t size) { TRASH(ptr_arg, size); }
uchar *ptr; // Position to field in record
uchar *null_ptr; // Byte where null_bit is
/**
Byte where the @c NULL bit is stored inside a record. If this Field is a
@c NOT @c NULL field, this member is @c NULL.
*/
uchar *null_ptr;
/*
Note that you can use table->in_use as replacement for current_thd member
only inside of val_*() and store() members (e.g. you can't use it in cons)
......@@ -261,6 +265,9 @@ class Field
inline void set_notnull(my_ptrdiff_t row_offset= 0)
{ if (null_ptr) null_ptr[row_offset]&= (uchar) ~null_bit; }
inline bool maybe_null(void) { return null_ptr != 0 || table->maybe_null; }
/**
Signals that this field is NULL-able.
*/
inline bool real_maybe_null(void) { return null_ptr != 0; }
enum {
......
/* Copyright (C) 2000-2003 MySQL AB
/* Copyright (c) 2000, 2010 Oracle and/or its affiliates. All rights reserved.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
......@@ -11,7 +11,7 @@
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
/**
......@@ -96,7 +96,7 @@ static ulonglong get_exact_record_count(TABLE_LIST *tables)
@param conds WHERE clause
@note
This function is only called for queries with sum functions and no
This function is only called for queries with aggregate functions and no
GROUP BY part. This means that the result set shall contain a single
row only
......@@ -559,31 +559,57 @@ bool simple_pred(Item_func *func_item, Item **args, bool *inv_order)
/**
Check whether a condition matches a key to get {MAX|MIN}(field):.
For the index specified by the keyinfo parameter, index that
contains field as its component (field_part), the function
checks whether the condition cond is a conjunction and all its
conjuncts referring to the columns of the same table as column
field are one of the following forms:
- f_i= const_i or const_i= f_i or f_i is null,
where f_i is part of the index
- field {<|<=|>=|>|=} const or const {<|<=|>=|>|=} field
- field between const1 and const2
For the index specified by the keyinfo parameter and an index that
contains the field as its component (field_part), the function
checks whether
@param[in] max_fl Set to 1 if we are optimising MAX()
@param[in,out] ref Reference to the structure we store the key
value
- the condition cond is a conjunction,
- all of its conjuncts refer to columns of the same table, and
- each conjunct is on one of the following forms:
- f_i = const_i or const_i = f_i or f_i IS NULL,
where f_i is part of the index
- field {<|<=|>=|>|=} const
- const {<|<=|>=|>|=} field
- field BETWEEN const_1 AND const_2
As a side-effect, the key value to be used for looking up the MIN/MAX value
is actually stored inside the Field object. An interesting feature is that
the function will find the most restrictive endpoint by over-eager
evaluation of the @c WHERE condition. It continually stores the current
endpoint inside the Field object. For a query such as
@code
SELECT MIN(a) FROM t1 WHERE a > 3 AND a > 5;
@endcode
the algorithm will recurse over the conjuction, storing first a 3 in the
field. In the next recursive invocation the expression a > 5 is evaluated
as 3 > 5 (Due to the dual nature of Field objects as value carriers and
field identifiers), which will obviously fail, leading to 5 being stored in
the Field object.
@param[in] max_fl Set to true if we are optimizing MAX(),
false means we are optimizing %MIN()
@param[in, out] ref Reference to the structure where the function
stores the key value
@param[in] keyinfo Reference to the key info
@param[in] field_part Pointer to the key part for the field
@param[in] cond WHERE condition
@param[in,out] key_part_used Map of matchings parts
@param[in,out] range_fl Says whether including key will be used
@param[in,out] key_part_used Map of matchings parts. The function will output
the set of key parts actually being matched in
this set, yet it relies on the caller to
initialize the value to zero. This is due
to the fact that this value is passed
recursively.
@param[in,out] range_fl Says whether endpoints use strict greater/less
than.
@param[out] prefix_len Length of common key part for the range
where MAX/MIN is searched for
@retval
0 Index can't be used.
false Index can't be used.
@retval
1 We can use index to get MIN/MAX value
true We can use the index to get MIN/MAX value
*/
static bool matching_cond(bool max_fl, TABLE_REF *ref, KEY *keyinfo,
......@@ -620,17 +646,20 @@ static bool matching_cond(bool max_fl, TABLE_REF *ref, KEY *keyinfo,
return 0; // Not operator, can't optimize
bool eq_type= 0; // =, <=> or IS NULL
bool is_null_safe_eq= FALSE; // The operator is NULL safe, e.g. <=>
bool noeq_type= 0; // < or >
bool less_fl= 0; // < or <=
bool is_null= 0;
bool between= 0;
bool is_null= 0; // IS NULL
bool between= 0; // BETWEEN ... AND ...
switch (((Item_func*) cond)->functype()) {
case Item_func::ISNULL_FUNC:
is_null= 1; /* fall through */
case Item_func::EQ_FUNC:
eq_type= TRUE;
break;
case Item_func::EQUAL_FUNC:
eq_type= 1;
eq_type= is_null_safe_eq= TRUE;
break;
case Item_func::LT_FUNC:
noeq_type= 1; /* fall through */
......@@ -658,6 +687,10 @@ static bool matching_cond(bool max_fl, TABLE_REF *ref, KEY *keyinfo,
if (!simple_pred((Item_func*) cond, args, &inv))
return 0;
if (!is_null_safe_eq && !is_null &&
(args[1]->is_null() || (between && args[2]->is_null())))
return FALSE;
if (inv && !eq_type)
less_fl= 1-less_fl; // Convert '<' -> '>' (etc)
......@@ -708,15 +741,16 @@ static bool matching_cond(bool max_fl, TABLE_REF *ref, KEY *keyinfo,
- field {>|>=} const, when searching for MIN
*/
if (is_null)
if (is_null || (is_null_safe_eq && args[1]->is_null()))
{
part->field->set_null();
*key_ptr= (uchar) 1;
}
else
{
store_val_in_field(part->field, args[between && max_fl ? 2 : 1],
CHECK_FIELD_IGNORE);
/* Update endpoints for MAX/MIN, see function comment. */
Item *value= args[between && max_fl ? 2 : 1];
store_val_in_field(part->field, value, CHECK_FIELD_IGNORE);
if (part->null_bit)
*key_ptr++= (uchar) test(part->field->is_null());
part->field->get_key_image(key_ptr, part->length, Field::itRAW);
......
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