{"id":"wal-single-writer-fd","text":"At most one file descriptor is open for WAL writes at any time; `_rotate` closes the old fd before opening the new one.","truth_value":"IN","source":"entries/2026/05/29/write-ahead-log-wal-_rotate.md","source_url":"","source_hash":"","justifications":[],"dependents":[],"metadata":{"example":"self._fd = open(self._current_file, \"ab\")\n# single file descriptor, all writes go through self._fd"},"explanation":{"steps":[{"node":"wal-single-writer-fd","truth_value":"IN","reason":"premise"}]}}