From 7f272dd98f75fec5db6dd732a52aa328e898a1e8 Mon Sep 17 00:00:00 2001
From: Robin Appelman <robin@icewind.nl>
Date: Mon, 18 Oct 2021 17:58:04 +0200
Subject: [PATCH] allow specifying index hints for mysql search queries

Signed-off-by: Robin Appelman <robin@icewind.nl>
---
 lib/private/DB/QueryBuilder/QueryBuilder.php  | 17 +++++++++++++++++
 lib/private/Files/Cache/CacheQueryBuilder.php | 19 ++++++++++++++++---
 2 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/lib/private/DB/QueryBuilder/QueryBuilder.php b/lib/private/DB/QueryBuilder/QueryBuilder.php
index 352829a56ae..82add039cf5 100644
--- a/lib/private/DB/QueryBuilder/QueryBuilder.php
+++ b/lib/private/DB/QueryBuilder/QueryBuilder.php
@@ -1301,4 +1301,21 @@ class QueryBuilder implements IQueryBuilder {
 
 		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/CacheQueryBuilder.php b/lib/private/Files/Cache/CacheQueryBuilder.php
index ac17cfaffb2..36f92c696d6 100644
--- a/lib/private/Files/Cache/CacheQueryBuilder.php
+++ b/lib/private/Files/Cache/CacheQueryBuilder.php
@@ -26,6 +26,7 @@ declare(strict_types=1);
 
 namespace OC\Files\Cache;
 
+use Doctrine\DBAL\Platforms\MySQLPlatform;
 use OC\DB\QueryBuilder\QueryBuilder;
 use OC\SystemConfig;
 use OCP\DB\QueryBuilder\IQueryBuilder;
@@ -45,12 +46,24 @@ class CacheQueryBuilder extends QueryBuilder {
 		$this->cache = $cache;
 	}
 
-	public function selectFileCache(string $alias = null) {
+	public function selectFileCache(string $alias = null, string $mysqlIndexHint = '') {
 		$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', $name)
-			->leftJoin($name, 'filecache_extended', 'fe', $this->expr()->eq("$name.fileid", 'fe.fileid'));
+			->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'));
+		}
 
 		$this->alias = $name;