Merge pull request #43185 from nextcloud/feat/db/dirty-queries-production

feat(db): Make dirty query logging available in production

config/config.sample.php

@@ -994,6 +994,15 @@ $CONFIG = [
  */
 'loglevel_frontend' => 2,
 
+/**
+ * Loglevel used by the dirty database query detection. Useful to identify
+ * potential database bugs in production. Set this to loglevel or higher to
+ * see dirty queries in the logs.
+ *
+ * Defaults to ``0`` (debug)
+ */
+'loglevel_dirty_database_queries' => 0,
+
 /**
  * If you maintain different instances and aggregate the logs, you may want
  * to distinguish between them. ``syslog_tag`` can be set per instance

lib/private/DB/Connection.php

@@ -276,7 +276,15 @@ class Connection extends PrimaryReadReplicaConnection {
 		} else {
 			// Read to a table that has been written to previously
 			// While this might not necessarily mean that we did a read after write it is an indication for a code path to check
-			$this->logger->debug('dirty table reads: ' . $sql, ['tables' => $this->tableDirtyWrites, 'reads' => $tables, 'exception' => new \Exception()]);
+			$this->logger->log(
+				(int) ($this->systemConfig->getValue('loglevel_dirty_database_queries', null) ?? 0),
+				'dirty table reads: ' . $sql,
+				[
+					'tables' => $this->tableDirtyWrites,
+					'reads' => $tables,
+					'exception' => new \Exception(),
+				],
+			);
 		}
 
 		$sql = $this->replaceTablePrefix($sql);