databasev2 3, task 6. Documentation, plus three gate-tolerance
corrections that are justified rather than silent.
- 04-db-binding.md: the NORMATIVE rule — compaction may run only where
nothing is staged (a correctness requirement, not scheduling), recovery
is unchanged, and a failed compaction is a missed optimisation rather
than a durability event
- database/src/CODE-LOGIC.md: why one file and not snapshot-plus-tail
(Postgres CANNOT compact — page deltas; ours are full row images, so a
compacted log IS a store), why rename is the whole crash-safety story,
why the dump flushes but does NOT fsync when it does, why the
replacement is preallocated, and where the trigger is checked
- README: the checkpoint knobs, the extended walstats line, the boot mode
- story -> status: done, with criteria split met/outstanding
- board: standup entry in the six-question shape, both rows rewritten
THE OBLIGATION IS AT THE COMPACTOR, not only in a spec: compaction moves
every record, so it invalidates every WAL offset iteration 2's
`resident: keys` stores, and the loop that knows each record's new
position must rebuild that map. Nothing fails today because that storage
half is unimplemented — it would fail later, looking like corruption.
Board claim corrected before it shipped: I wrote that the concurrency
chain is "complete". It is not — chain 5 stays in-progress because
databasev2 4's part B was never done and its premise was invalidated by
part A. Every link has landed its PLANNED work; that is a different
statement.
Gate tolerances, each with the measurement that justifies it:
- ckpt.pause_us_max is no longer gated relatively. The raw pause scales
with the live set and this workload's live set is not fixed (wmix's
hist_dump inserts a row per latency bucket), so gating it gates the
box. Added ckpt.pause_us_per_mb — the engine's own rate, gated for
real, and the metric that would have caught the 8x dump regression —
with the absolute 50ms budget still guarding the raw pause
- ram.*.msgrate 15% -> 70%. PRE-EXISTING, and measured: 10.7M-17.9M
msgs/sec across ten full runs, several predating this work — a 1.67x
spread against a 15% gate
- durable.sN.*.p99us 100% -> 300%, with more evidence than the first
widening: mixread 1043/2318/4147us, mixwrite 1623/4446us on the same
build. Floors stay the real guard and are not slack
Battery: wovm-test 36 suites 0 fail, woc-test, oop-e2e 119/0,
db-bench 117 checks 0 failures, linkcheck clean.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
shoney.arickathil
8b29eb492c