[stable5.5] fix(db): clean-up old mailboxes account_id+name index

lib/Migration/Version0161Date20190902103701.php

@@ -75,11 +75,14 @@ public function changeSchema(IOutput $output, Closure $schemaClosure, array $opt
 			'default' => true,
 		]);
 		$mailboxTable->setPrimaryKey(['id']);
-		// We allow each mailbox name just once
-		$mailboxTable->addUniqueIndex([
-			'account_id',
-			'name',
-		]);
+		/*
+		 * We allow each mailbox name just once
+		 * @see \OCA\Mail\Migration\Version3500Date20231115184458::changeSchema
+		 */
+		// $mailboxTable->addUniqueIndex([
+		// 	'account_id',
+		// 	'name',
+		// ]);
 
 		return $schema;
 	}

lib/Migration/Version3500Date20231115184458.php

@@ -28,11 +28,20 @@ public function changeSchema(IOutput $output, Closure $schemaClosure, array $opt
 
 		$mailboxesTable = $schema->getTable('mail_mailboxes');
 
-		$indexOld = 'UNIQ_22DEBD839B6B5FBA5E237E06';
 		$indexNew = 'mail_mb_account_id_name_hash';
 
-		if ($mailboxesTable->hasIndex($indexOld)) {
-			$mailboxesTable->dropIndex($indexOld);
+		/**
+		 * Variant 1 - with table prefix
+		 */
+		if ($mailboxesTable->hasIndex('UNIQ_22DEBD839B6B5FBA5E237E06')) {
+			$mailboxesTable->dropIndex('UNIQ_22DEBD839B6B5FBA5E237E06');
+		}
+		/**
+		 * Variant 2 - without table prefix
+		 * @see \OCA\Mail\Migration\Version5006Date20250927130132::changeSchema
+		 */
+		if ($mailboxesTable->hasIndex('UNIQ_45754FF89B6B5FBA5E237E06')) {
+			$mailboxesTable->dropIndex('UNIQ_45754FF89B6B5FBA5E237E06');
 		}
 
 		if (!$mailboxesTable->hasIndex($indexNew)) {

lib/Migration/Version5006Date20250927130132.php

@@ -26,6 +26,17 @@ public function changeSchema(IOutput $output, Closure $schemaClosure, array $opt
 		$schema = $schemaClosure();
 
 		$mailboxes = $schema->getTable('mail_mailboxes');
+
+		/**
+		 * Make sure the old account_id+name index is gone. The DB won't allow
+		 * the name length increase otherwise
+		 *
+		 * @see \OCA\Mail\Migration\Version3500Date20231115184458::changeSchema
+		 */
+		if ($mailboxes->hasIndex('UNIQ_45754FF89B6B5FBA5E237E06')) {
+			$mailboxes->dropIndex('UNIQ_45754FF89B6B5FBA5E237E06');
+		}
+
 		$mailboxes->modifyColumn(
 			'name',
 			['length' => 1024]

lib/Migration/Version5006Date20251015082003.php

@@ -0,0 +1,46 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2025 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\Mail\Migration;
+
+use Closure;
+use OCP\DB\ISchemaWrapper;
+use OCP\Migration\IOutput;
+use OCP\Migration\SimpleMigrationStep;
+use Override;
+
+class Version5006Date20251015082003 extends SimpleMigrationStep {
+
+	/**
+	 * @param IOutput $output
+	 * @param Closure(): ISchemaWrapper $schemaClosure
+	 * @param array $options
+	 * @return null|ISchemaWrapper
+	 */
+	#[Override]
+	public function changeSchema(IOutput $output, Closure $schemaClosure, array $options): ?ISchemaWrapper {
+		$schema = $schemaClosure();
+
+		/**
+		 * Make sure the old account_id+name index is gone for good
+		 *
+		 * @see \OCA\Mail\Migration\Version3500Date20231115184458::changeSchema
+		 */
+		$mailboxesTable = $schema->getTable('mail_mailboxes');
+		if (!$mailboxesTable->hasIndex('UNIQ_45754FF89B6B5FBA5E237E06')) {
+			// Nothing to do
+			return null;
+		}
+
+		$mailboxesTable->dropIndex('UNIQ_45754FF89B6B5FBA5E237E06');
+
+		return $schema;
+	}
+
+}