From 5b89d3439729e01a610e7ebf685282fd0bd09ba2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20Molakvo=C3=A6?= <skjnldsv@users.noreply.github.com>
Date: Thu, 4 Nov 2021 11:10:46 +0100
Subject: [PATCH] Revert "[21] tell mysql to ignore the sort index for search
 queries"

---
 lib/private/DB/QueryBuilder/QueryBuilder.php  | 17 -----------------
 lib/private/Files/Cache/Cache.php             |  8 +-------
 lib/private/Files/Cache/CacheQueryBuilder.php | 19 +++----------------
 3 files changed, 4 insertions(+), 40 deletions(-)

diff --git a/lib/private/DB/QueryBuilder/QueryBuilder.php b/lib/private/DB/QueryBuilder/QueryBuilder.php
index 82add039cf551..352829a56ae79 100644
--- a/lib/private/DB/QueryBuilder/QueryBuilder.php
+++ b/lib/private/DB/QueryBuilder/QueryBuilder.php
@@ -1301,21 +1301,4 @@ public function quoteAlias($alias) {
 
 		return $this->helper->quoteColumnName($alias);
 	}
-
-	/**
-	 * Either appends to or replaces a single, generic query part.
-	 *
-	 * The available parts are: 'select', 'from', 'set', 'where',
-	 * 'groupBy', 'having' and 'orderBy'.
-	 *
-	 * @param string $sqlPartName
-	 * @param mixed  $sqlPart
-	 * @param bool   $append
-	 *
-	 * @return $this This QueryBuilder instance.
-	 */
-	public function add(string $sqlPartName, $sqlPart, bool $append = false) {
-		$this->queryBuilder->add($sqlPartName, $sqlPart, $append);
-		return $this;
-	}
 }
diff --git a/lib/private/Files/Cache/Cache.php b/lib/private/Files/Cache/Cache.php
index 4e5edc0e0a6bf..34ed6d33a2d8c 100644
--- a/lib/private/Files/Cache/Cache.php
+++ b/lib/private/Files/Cache/Cache.php
@@ -848,13 +848,7 @@ public function searchByMime($mimetype) {
 	protected function buildSearchQuery(ISearchQuery $searchQuery): IQueryBuilder {
 		$builder = $this->getQueryBuilder();
 
-		// mysql really likes to pick an index for sorting if it can't fully satisfy the where
-		// filter with an index, since search queries pretty much never are fully filtered by index
-		// mysql often picks an index for sorting instead of the *much* more useful index for filtering.
-		//
-		// To bypass this, we tell mysql explicitly not to use the mtime (the default order field) index,
-		// so it will instead pick an index that is actually useful.
-		$query = $builder->selectFileCache('file', 'ignore index for order by (fs_mtime)');
+		$query = $builder->selectFileCache('file');
 
 		$query->whereStorageId();
 
diff --git a/lib/private/Files/Cache/CacheQueryBuilder.php b/lib/private/Files/Cache/CacheQueryBuilder.php
index 9847375495e30..2215cef9a15a0 100644
--- a/lib/private/Files/Cache/CacheQueryBuilder.php
+++ b/lib/private/Files/Cache/CacheQueryBuilder.php
@@ -26,7 +26,6 @@
 
 namespace OC\Files\Cache;
 
-use Doctrine\DBAL\Platforms\MySQLPlatform;
 use OC\DB\QueryBuilder\QueryBuilder;
 use OC\SystemConfig;
 use OCP\DB\QueryBuilder\IQueryBuilder;
@@ -46,24 +45,12 @@ public function __construct(IDBConnection $connection, SystemConfig $systemConfi
 		$this->cache = $cache;
 	}
 
-	public function selectFileCache(string $alias = null, string $mysqlIndexHint = '') {
+	public function selectFileCache(string $alias = null) {
 		$name = $alias ? $alias : 'filecache';
 		$this->select("$name.fileid", 'storage', 'path', 'path_hash', "$name.parent", 'name', 'mimetype', 'mimepart', 'size', 'mtime',
 			'storage_mtime', 'encrypted', 'etag', 'permissions', 'checksum', 'metadata_etag', 'creation_time', 'upload_time')
-			->from('filecache', $name);
-		if ($mysqlIndexHint !== '' && $this->getConnection()->getDatabasePlatform() instanceof MySQLPlatform) {
-			$this->add('join', [
-				$this->quoteAlias($name) => [
-					// horrible query builder crimes to sneak in raw sql after the "FROM oc_filecache $name"
-					'joinType' => $mysqlIndexHint . ' left',
-					'joinTable' => $this->getTableName('filecache_extended'),
-					'joinAlias' => $this->quoteAlias('fe'),
-					'joinCondition' => $this->expr()->eq("$name.fileid", 'fe.fileid'),
-				],
-			], true);
-		} else {
-			$this->leftJoin($name, 'filecache_extended', 'fe', $this->expr()->eq("$name.fileid", 'fe.fileid'));
-		}
+			->from('filecache', $name)
+			->leftJoin($name, 'filecache_extended', 'fe', $this->expr()->eq("$name.fileid", 'fe.fileid'));
 
 		$this->alias = $name;