databasev2 2, task 5c. The write and boot halves. Still not exposed: the
loader refuses `resident: keys` until 5d rewires the readers.
GROUP COMMIT FORCED THE DESIGN. A keys-resident payload can only be dropped
once its record is durable, but databasev2 4 deferred the barrier to the drain
— so at append time the bytes are still in the staging buffer and the recorded
offset would pread ZEROS. Dropping at append would have produced rows that
read as garbage, intermittently, only under multi-shard load.
So the drop is recorded, not performed:
- wo_wal gains a pending-drop list, the same shape as the drain's held replies
and for the same reason
- both write paths take the offset BEFORE the append (wo_wal_next_offset) and
record it; the inline path flushes right after its own commit, the request
path's flush runs in the drain immediately after the barrier
- if the process dies before the barrier the list dies with it, which is
correct: nothing was dropped and nothing was lost
- an out-of-memory pend is ignored on purpose — the row simply stays resident,
which is safe
Boot: replay now leaves a keys-resident table pointing at the LOG. Each record
is applied normally, so indexes and uniqueness are built exactly as for any
other table, and the payload is then dropped with THAT record's offset. For an
update the later record wins, because each apply overwrites the map in order —
the rule replay already follows.
Tests: the round trip (insert, commit, drop, read back with Text intact) and
now BOOT — a fresh wo_db replays the store and every row materialises from the
log, count intact, nothing in a slab.
Verified: just wovm-test — 36 suites 0 fail, test_wal 4301 pass, cli_smoke OK.
REMAINING (5d), and precise: every reader still goes through wo_row_ptr, which
for a keys table would index a freed slot. The scans in db.c walk the BITMAP,
and a keys table's bitmap is empty by construction — so a query over one would
today return no rows at all. That, FK restrict, and the @unique shadow are 5d,
and the loader refusal stays until they land.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
(cherry picked from commit 08abd09bf88918f2582e74713dc7903beb8aaeb8)
shoney.arickathil
e16d4896f8