[BUGFIX] Mitigate query buffer issue in OptimizeDatabaseTableTask

Using `pdo_mysql` driver with `MySQL` and `MariaDB` databases
requires that buffered result sets are fully read or explicitly
free'd. That means, that queries returning a result set needs
to consume the full result set by reading all rows and not only
one record and leaving the rest in the buffer.

TYPO3 mitigates this in several places for select queries by
explicitly enforcing `setMaxResults(1)` when reading only one
record and it could be a duplicates, which is not an ideal or
reading the full result set.

The DDL `OPTIMIZE TABLE` for `MariaDB` and `MySQL` databases
returns a result stating the outcome of the operation and is
a buffered query, which requires to use `executeQuery()` and
not `executeStatement()` on the connection and fully consume
the result when using `pdo_mysql`. However, the  `mysqli`
driver is more forgiving here.

This change now uses `executeQuery()` in the scheduler task
`OptimizeDatabaseTableTask` to retrieve the result without
using it to ensure buffer is consumed and works with both
possible drivers for the aforementioned database vendors.

As a first guard, one functional test execution is changed
to use `pdo_mysql` and is scheduled to rework the matrix
in a dedicated change to cover differences with both drivers
for `MySQL` and `MariaDB`.

Can be verified executing the single test case, working with
`mysqli` and failing with `pdo_mysql` (without this change):

> Build/Scripts/runTests.sh -s functional -d mariadb -a mysqli -- \
  --filter 'OptimizeDatabaseTableTaskTest'
> Build/Scripts/runTests.sh -s functional -d mariadb -a pdo_mysql -- \
  --filter 'OptimizeDatabaseTableTaskTest'
> Build/Scripts/runTests.sh -s functional -d mysql -a mysqli -- \
  --filter 'OptimizeDatabaseTableTaskTest'
> Build/Scripts/runTests.sh -s functional -d mysql -a pdo_mysql -- \
  --filter 'OptimizeDatabaseTableTaskTest'

Added tests are executed against all databases albeit the task
silently does nothing for other database systems than `MariaDB`
or `MySQL` to ensure that the platform detection stays in place.

TYPO3 v12 used the `Connection::query()` method using
`executeQuery()` internally, which means that it has
been replaced with the wrong method while upgrading to
Doctrine DBAL 4 with #102875 in TYPO3 v13.

Resolves: #106563
Related: #102875
Releases: main, 13.4
Change-Id: Ie8cc10d917ea7695da826bb7f8ec5dfeba2c89bf
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/89082
Reviewed-by: Garvin Hicking <gh@faktor-e.de>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Garvin Hicking <gh@faktor-e.de>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Benni Mack <benni@typo3.org>

Author: sbuerk

Build/gitlab-ci/pre-merge/functional.yml

@@ -1,4 +1,4 @@
-functional mariadb 10.4 php 8.3 pre-merge:
+functional mariadb 10.4 php 8.3 pdo_mysql pre-merge:
   stage: main
   tags:
     - metal2
@@ -9,7 +9,7 @@ functional mariadb 10.4 php 8.3 pre-merge:
   parallel: 6
   script:
     - Build/Scripts/runTests.sh -s composerInstall -p 8.3
-    - Build/Scripts/runTests.sh -s functional -d mariadb -i 10.4 -p 8.3 -c $CI_NODE_INDEX/$CI_NODE_TOTAL
+    - Build/Scripts/runTests.sh -s functional -d mariadb -a pdo_mysql -i 10.4 -p 8.3 -c $CI_NODE_INDEX/$CI_NODE_TOTAL
 
 functional postgres 10 php 8.4 pre-merge:
   stage: main

typo3/sysext/scheduler/Classes/Task/OptimizeDatabaseTableTask.php

@@ -53,7 +53,11 @@ public function execute()
 
             if ($platform instanceof DoctrineMariaDBPlatform || $platform instanceof DoctrineMySQLPlatform) {
                 try {
-                    $connection->executeStatement('OPTIMIZE TABLE ' . $connection->quoteIdentifier($tableName));
+                    // `OPTIMIZE TABLE` returns a result set and must be executed using `executeQuery()`,
+                    // otherwise following database queries would fail with a database exception because of a
+                    // not-consumed query buffer with `pdo_mysql` driver and the full result set is retrieved
+                    // with `fetchAllAssociative()` and discarded as handling is not intended here.
+                    $connection->executeQuery('OPTIMIZE TABLE ' . $connection->quoteIdentifier($tableName))->fetchAllAssociative();
                 } catch (DBALException $e) {
                     throw new \RuntimeException(
                         TableGarbageCollectionTask::class . ' failed for: ' . $tableName . ': ' .

typo3/sysext/scheduler/Tests/Functional/Task/OptimizeDatabaseTableTaskTest.php

@@ -0,0 +1,56 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the TYPO3 CMS project.
+ *
+ * It is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License, either version 2
+ * of the License, or any later version.
+ *
+ * For the full copyright and license information, please read the
+ * LICENSE.txt file that was distributed with this source code.
+ *
+ * The TYPO3 project - inspiring people to share!
+ */
+
+namespace TYPO3\CMS\Scheduler\Tests\Functional\Task;
+
+use PHPUnit\Framework\Attributes\Test;
+use TYPO3\CMS\Scheduler\Task\OptimizeDatabaseTableTask;
+use TYPO3\TestingFramework\Core\Functional\FunctionalTestCase;
+
+final class OptimizeDatabaseTableTaskTest extends FunctionalTestCase
+{
+    protected array $coreExtensionsToLoad = ['scheduler'];
+
+    #[Test]
+    public function executedSuccessfullyWithOneSelectedTable(): void
+    {
+        $selectedTables = ['be_users'];
+        $optimizeDatabaseTableTask = new OptimizeDatabaseTableTask();
+        $optimizeDatabaseTableTask->setTaskParameters([
+            'tables' => $selectedTables,
+        ]);
+        self::assertSame($selectedTables, (new \ReflectionProperty($optimizeDatabaseTableTask, 'selectedTables'))->getValue($optimizeDatabaseTableTask));
+        self::assertTrue($optimizeDatabaseTableTask->execute());
+    }
+
+    #[Test]
+    public function executedSuccessfullyWithMultipleSelectedTables(): void
+    {
+        $selectedTables = [
+            'be_users',
+            'be_groups',
+            'pages',
+            'tt_content',
+        ];
+        $optimizeDatabaseTableTask = new OptimizeDatabaseTableTask();
+        $optimizeDatabaseTableTask->setTaskParameters([
+            'tables' => $selectedTables,
+        ]);
+        self::assertSame($selectedTables, (new \ReflectionProperty($optimizeDatabaseTableTask, 'selectedTables'))->getValue($optimizeDatabaseTableTask));
+        self::assertTrue($optimizeDatabaseTableTask->execute());
+    }
+}