databasev2 4 part A, task 6. Mostly documentation, plus one real fix the
full battery caught.
THE FIX. The drain held EVERY DB reply until the barrier — including
reads, which stage nothing and have no stake in durability. That parked
readers behind an fsync for no reason: durable.sN.mixread.p99 rose from
~1043us to 4057us. Only a statement that actually staged a record now has
its reply held. Caught by the gate, not by review.
THE TRADE, recorded rather than smoothed over. What remains is inherent: a
barrier blocks the owner shard LONGER (more records per fsync) though LESS
OFTEN, so anything queued behind one waits. Three full runs of the same
build gave durable.sN.mixread.p99 of 1043 / 2318 / 4147us and wmix.p99 of
8758 / 20000us — a 2-4x spread with the box near idle. So part A buys ~3x
write throughput at the cost of a longer, noisier tail on the owner shard,
and that is the strongest argument for part B (submit and keep serving).
- durable.sN.*.p99us tolerance widened to 100% WITH the reason in the
code: a 2-4x-variable tail gated at 50% gates the disk, not the engine.
The floor is the real guard and is not slack — mixread's (4172us) came
within 25us of tripping on the worst run. Baseline refreshed; a fresh
full run then passed 106 checks 0 failures
EXIT STATUS MOVED 3 -> 74 (sysexits EX_IOERR). 3 and 4 are already used by
SAMPLES for their own meanings — db-bench's own `verify` exits 3 on a
checksum mismatch, and it is the gate that exercises durability, so a
durability abort exiting 3 would have been indistinguishable from the
mismatch it should help diagnose. The low range belongs to programs.
Docs:
- story: progress, the payoff measured two ways, the cost side, criteria
split met/outstanding, and a "part B — its premise changed" section:
it was justified by "close the 66x gap", but that gap is two problems
and only the concurrent one was a batching problem
- board: standup entry in the six-question shape; both databasev2 4 rows
rewritten. They had said "close the 66x gap" — recorded as MIS-STATED
rather than quietly renumbered
- 00-wob-format.md and 04-db-binding.md: the normative failure contract
("a failed WAL commit traps WO_T_IO after un-applying the row") was
false; corrected, along with the tick-scoped group commit that never
happened
- database/src/CODE-LOGIC.md: where the barrier runs and why there, why
replies are held, why the inline path is asymmetric, the one failure
rule, and how to measure it
- db-bench README: the wmix mode, the env knobs, and the tmpfs warning
Battery: wovm-test 36 suites 0 fail, woc-test, oop-e2e 119/0,
db-bench 106/0, linkcheck clean.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
- engine: wo_idx_probe answers single-column equality from the index
hash buckets (idx_hash_key1 reproduces idx_hash bit for bit; verify
compares exactly as the slab walk did, so results identical);
composite indexes keep the walk; both executors wired (local + DB
actor RPC)
- compiler: probe_key_of_where lowers "var.col == key" on an indexed
column to DB_PROBE; all where guards still run (guard stays the
final arbiter); keys = ident/int-literal only; Float/Bytes excluded
(engine raw-eq narrower than VM float-eq)
- measured: reads 1.3k -> 1.3M ops/s, p50 600us -> 1us (~x850);
query x830; mixread 1.3k -> 89k s1, 21 -> ~1.9k sN
- gate policy moved into the driver (tolerance_for: refresh-proof);
latency floors max(4x,100us); quick mode skips poll-bound mix
floors; both tolerance classes proven to bite
- proof: test_table wo_idx_probe suite (RED first), corpus
query-index-probe 105/0, full battery green, TSan clean, two
campaigns pass the refreshed baseline
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
- compiler: `insert Class { ... }` is a typed Ast.Insert in statement
AND expression position, sharing the ctor literal's field grammar;
typechecked with the ctor's omittable rule; result = the row id (Int)
- owner pass: the engine copies at the row API, so an insert BORROWS
its field values -- no transfer, no E304; node is trap-capable and
carries a live-mask drop entry like DbStub did
- emit: builtin 61 window = class-id const + one slot per DECLARED
field in declaration order; omitted defaults emitted, omitted ?scalar
gets WO_NIL_SCALAR, other omitted optionals the zero word; fresh
argument values reaped after (the push/set copy semantics)
- runtime: database/src/db.c executes via the choke-point row API;
rt.db/rt.wal opaque handles on wo_rt; WO_DATA=<dir> = replay
<dir>/shard-0.wal at boot + commit-before-ack per statement (the
builtin's return IS the ack until iteration 8 ticks); failed commit
un-applies the row and traps WO_T_IO; loader validates the class-id
slot (variable window documented in wob.h + format doc)
- the promised diff: trap/pricing-set-price-db-stub is now
run/pricing-set-price-insert printing engine-allocated ids;
durability smoke prints 1,2 then 3,4 across two WO_DATA runs
- old "bare insert is an Ident" unit test rewritten to the new
contract; runner's loader mirror accepts id 61; goldens re-blessed
- gates: oop-accept ALL CRITERIA MET, oop-e2e 71/0, woc-test 566/0,
wovm-test green, log-watcher 7/0
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
- database/src/wal.{c,h}: framed records len|crc32|payload|mark
("WOL1" written last -- no mark, no record), typed-row payloads
walking the class-table kinds (nested records, containers, nil
encodings), little-endian like the loader
- commit order verbatim from the shipped phase-D pattern: RAM apply,
stage, ONE pwrite + ONE fdatasync for the batch, ack after -- group
commit is everything staged riding one sync
- replay decodes straight into engine-owned values (no VM at boot)
and re-enters rows through the choke-point row API, so Task 4's
indexes will rebuild for free; next_id advances past replayed ids
this shard owns (wo_row_create_raw)
- torn tail = short/CRC-fail/no-mark/zero-len: intact prefix applies,
tear dropped whole, wo_wal_open positions AT the tear so the next
commit overwrites it; CRC-valid-but-undecodable = corruption, loud
- wo_wal_check: offline oracle, no engine needed -- the crash
battery's verifier
- test_wal 90/0 ASan+UBSan incl. five crash-battery rounds (fork,
insert/commit/ack-over-pipe, SIGKILL mid-stream: zero acked-but-
missing, zero acked-but-wrong); all runtime suites green, oop-e2e
71/0; binding doc WAL section + CODE-LOGIC + plan Task 2 checked
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
- database/src/table.{c,h}: per-shard per-class slabs (256 rows,
malloc'd, never moved -- row addresses stable for 9b's row views),
occupancy bitmap, LIFO slot reuse, open-addressing id hash with
tombstones (ids never 0, never reused)
- field encoding walks the same .wob class-table kinds the VM walks:
scalars raw (WO_NIL_SCALAR passes through), Texts copied to db_text,
owned objects flattened recursively to db_rec, containers
element-wise; GCREF refused at encode (the GC bulkhead, defensively)
- two one-way copy gates: insert copies VM values in, read allocates
fresh VM values out -- no VM pointer in a slab, no slab pointer in
the VM, proven by mutating originals after insert
- id discipline: per table per shard, S+1 step N; owner = (id-1) % N;
N-parametric, runs at N=1 until iteration 8, tested at N=3
- choke points: wo_row_insert/wo_row_remove carry the INDEX HOOK
sites Task 4 attaches to; nothing else mutates storage
- runtime/Makefile links database/src into every wovm + test binary
- test_table 827/0 ASan+UBSan; oop-e2e 71/0; log-watcher 7/0;
binding doc docs/plan/oop-vm/04-db-binding.md; CODE-LOGIC.md beside
the code; plan Task 1 checked off
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
