{"id":"batch-mode-defers-fsync","text":"In `batch` sync mode, individual WAL appends do not fsync until `_write_count` reaches `_batch_sync_count` (default 100), leaving up to 99 records vulnerable to crash loss","truth_value":"IN","source":"entries/2026/05/29/topic-fsync-semantics-by-mode.md","source_url":"","source_hash":"","justifications":[],"dependents":[],"metadata":{"example":"elif self._sync_mode == \"batch\":\n    self._write_count += 1\n    if self._write_count >= self._batch_sync_count:\n        self._fd.flush()\n        os.fsync(self._fd.fileno())\n        self._write_count = 0"},"explanation":{"steps":[{"node":"batch-mode-defers-fsync","truth_value":"IN","reason":"premise"}]}}