Adding PostId index (#5300)

store/sql_file_info_store.go

@@ -33,6 +33,7 @@ func (fs SqlFileInfoStore) CreateIndexesIfNotExists() {
 	fs.CreateIndexIfNotExists("idx_fileinfo_update_at", "FileInfo", "UpdateAt")
 	fs.CreateIndexIfNotExists("idx_fileinfo_create_at", "FileInfo", "CreateAt")
 	fs.CreateIndexIfNotExists("idx_fileinfo_delete_at", "FileInfo", "DeleteAt")
+	fs.CreateIndexIfNotExists("idx_fileinfo_postid_at", "FileInfo", "PostId")
 }
 
 func (fs SqlFileInfoStore) Save(info *model.FileInfo) StoreChannel {