querylog: checkpoint every 8192 wal pages instead of 1000

2026-08-21 18:43:45 +02:00
parent 324704b53f
commit 9b0b7c19f4
7 changed files with 140 additions and 3 deletions
@@ -19,6 +19,10 @@ Model key + round-trip drift guards, validation + validation reference, settings
 - Crash-loss window: up to `interval` seconds of query history on process failure; power loss can additionally lose recent committed transactions (WAL + synchronous=NORMAL). Query history is the least valuable data on the box.
 - Staleness: every query-log-backed read (query-log page, totals, timeseries) lags up to `interval` seconds. The live view is unaffected — it is fed from the hub before the queue.

+## Follow-up
+
+The "unchanged on purpose" line above no longer holds for `wal_autocheckpoint`. Batching landed and the Pi measured 0.281 GiB/day, of which ~130 MiB is autocheckpoint writeback — second-order next to one transaction per query, first-order next to one per minute. specs/querylog-autocheckpoint.md raises the threshold to 8192 pages on every read-write `querylog.db` connection and states the durability contract that comes with it. Nothing else in this spec changes.
+
 ## Acceptance

 - [ ] Deterministic tests: interval batching (entries within the window land in one transaction), flush_batch early flush, 0-sentinel immediate flush, shutdown drains a held batch and the queue (the race sequence: producers stopped → queue closed → writer awaited), disk-gated final drain counts drops.