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MDEV-38649: Wrong result upon condition pushdown on table with DESC key #4687

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MDEV-38649: Wrong result upon condition pushdown on table with DESC key #4687

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7b54798
MDEV-38649: Wrong result upon condition pushdown to table with DESC key
DaveGosselin-MariaDB Feb 19, 2026
520fc4b
MDEV-38649: Wrong result upon condition pushdown on table with DESC key
DaveGosselin-MariaDB Feb 23, 2026
d66580c
MDEV-38921: Incorrect ORDER BY Result
DaveGosselin-MariaDB Feb 27, 2026
eea1fa8
MDEV-38921: Incorrect ORDER BY Result
DaveGosselin-MariaDB Feb 27, 2026
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32 changes: 32 additions & 0 deletions mysql-test/main/order_by.result
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Original file line number Diff line number Diff line change
Expand Up @@ -4849,4 +4849,36 @@ ERROR 42S22: Unknown column '-5' in 'ORDER BY'
SELECT 1 FROM (select 1) dt order BY 50;
ERROR 42S22: Unknown column '50' in 'ORDER BY'
# End of 10.11 tests
#
# MDEV-38649: Wrong result (missing rows) upon condition pushdown on table with DESC key
#
CREATE TABLE t1 (a INT, b INT not null, KEY(b));
INSERT INTO t1 VALUES (2,8),(9,1),(4,6);
SELECT a, b FROM t1 WHERE b != 10 and b < 30 ORDER BY b DESC;
a b
2 8
4 6
9 1
SELECT a, b FROM t1 use index() WHERE b != 10 and b < 30 ORDER BY b DESC;
a b
2 8
4 6
9 1
DROP TABLE t1;
#
# End of 12.3 tests
#
#
# MDEV-38921: Incorrect ORDER BY Result
#
CREATE TABLE t2 (a INT, b INT not null, KEY(b));
INSERT INTO t2 VALUES (2,8),(9,1),(4,6),(11,13),(15,17);
SELECT a, b FROM t2 WHERE b != 10 and b < 30 ORDER BY b DESC;
a b
15 17
11 13
2 8
4 6
9 1
DROP TABLE t2;
ALTER DATABASE test CHARACTER SET utf8mb4 COLLATE utf8mb4_uca1400_ai_ci;
21 changes: 21 additions & 0 deletions mysql-test/main/order_by.test
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Expand Up @@ -2831,4 +2831,25 @@ SELECT 1 FROM (select 1) dt order BY 50;

--echo # End of 10.11 tests

--echo #
--echo # MDEV-38649: Wrong result (missing rows) upon condition pushdown on table with DESC key
--echo #
CREATE TABLE t1 (a INT, b INT not null, KEY(b));
INSERT INTO t1 VALUES (2,8),(9,1),(4,6);
SELECT a, b FROM t1 WHERE b != 10 and b < 30 ORDER BY b DESC;
SELECT a, b FROM t1 use index() WHERE b != 10 and b < 30 ORDER BY b DESC;
DROP TABLE t1;

--echo #
--echo # End of 12.3 tests
--echo #

--echo #
--echo # MDEV-38921: Incorrect ORDER BY Result
--echo #
CREATE TABLE t2 (a INT, b INT not null, KEY(b));
INSERT INTO t2 VALUES (2,8),(9,1),(4,6),(11,13),(15,17);
SELECT a, b FROM t2 WHERE b != 10 and b < 30 ORDER BY b DESC;
DROP TABLE t2;

--source include/test_db_charset_restore.inc
10 changes: 6 additions & 4 deletions sql/opt_range.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -13904,7 +13904,7 @@ int QUICK_SELECT_DESC::get_next()
* step back once, and move backwards
*/

for (;;)
for (;; last_range= nullptr, file->set_end_range(nullptr))
{
int result;
if (last_range)
Expand Down Expand Up @@ -13953,7 +13953,7 @@ int QUICK_SELECT_DESC::get_next()
DBUG_RETURN(local_error); // Empty table
if (cmp_prev(last_range) == 0)
DBUG_RETURN(0);
last_range= 0; // No match; go to next range
// No match; go to next range
continue;
}

Expand All @@ -13974,6 +13974,8 @@ int QUICK_SELECT_DESC::get_next()
last_range->make_min_endpoint(&min_range);
if (min_range.length > 0)
file->set_end_range(&min_range, handler::RANGE_SCAN_DESC);
else
file->set_end_range(nullptr);

DBUG_ASSERT(last_range->flag & NEAR_MAX ||
(last_range->flag & EQ_RANGE &&
Expand All @@ -13989,7 +13991,7 @@ int QUICK_SELECT_DESC::get_next()
{
if (result != HA_ERR_KEY_NOT_FOUND && result != HA_ERR_END_OF_FILE)
DBUG_RETURN(result);
last_range= 0; // Not found, to next range
// Not found, to next range
continue;
}
if (cmp_prev(last_range) == 0)
Expand All @@ -13998,7 +14000,7 @@ int QUICK_SELECT_DESC::get_next()
last_range= 0; // Stop searching
DBUG_RETURN(0); // Found key is in range
}
last_range= 0; // To next range
// To next range
}
}

Expand Down