shoney.arickathil
881b90e9c7
- 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>
68 lines
3.7 KiB
Markdown
68 lines
3.7 KiB
Markdown
# db-bench — iteration 22's load generator
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The measurement backbone (spec:
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`docs/superpowers/specs/2026-08-21-db-bench-design.md`). Pure `.wo`;
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every measured mode prints one machine-parsable line per operation
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class:
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<op> <count> <ops/sec> <p50us> <p99us>
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Timing is per-operation via `time.ticks` (CLOCK_MONOTONIC µs).
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Percentiles come from a 1µs-bucket histogram clamped at 20000µs — exact
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to the microsecond below the clamp; a p99 AT 20000 means "clamp or
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worse". (A histogram, not the spec's reservoir: the language has no
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container element-write or sort, and the histogram's tail fidelity is
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strictly better. Recorded as a plan deviation.)
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## Modes
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| mode | what it prices |
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| --- | --- |
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| `all N` | the throughput campaign in ONE process: seed N, read N/2, query N/10, write N/2. Without `WO_DATA` the store is RAM and dies with the process, so the measured modes must share the seeding run. |
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| `seed N` | timed inserts: one parent per 100 children (FK probe each insert, unique-index maintenance per parent), k non-unique (10 rows/key), deterministic v. Writes `Meta` expectation rows. |
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| `read N` | indexed take-1 point lookups, LCG-spread keys. |
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| `query N` | full equality probes on the k index (≈10 rows each), materialized and counted. |
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| `write N` | alternating inserts (disjoint k range 2e6+) and updates through query results. Corrupts the checksum by design — durability legs run on a fresh store. |
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| `wal N` | the crash battery's vehicle: insert-only (k range 1e6+), `acked <i>` printed AFTER each insert returns — the return IS the ack (RAM applied, WAL record staged, ONE commit done). |
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| `verify` | store vs its own Meta rows: count, checksum, one unique probe. Exit 3 on mismatch. |
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| `verify-acked M` | after kill -9 mid-`wal`: rows 1..M exist with the right v; rows beyond M allowed (acked after the last print flushed). Exit 3 on mismatch. |
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## Coordination idiom (this side of iteration 31)
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There is no request/response surface yet: concurrent modes drive
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completion the db-actor way — actors write rows, main polls the store
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until the expected count, then settles. Retired when 31 lands.
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## Standing finding (2026-08-21, first run)
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A hand-built `multi Bucket` of insert results SEGVs on drop: the
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compiler classifies the elements OWNED while table refs are scalar ids.
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Query-built multis are runtime-typed and safe. Worked around here
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(single ref local, bucket-major seeding); the compiler fix is its own
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slice.
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## Reference-machine numbers (first campaign, 2026-08-21)
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`bench/baseline.json` is the contract; headline readings:
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- ram seed 245–290k inserts/s; **durable seed ≈4.5k/s** (fsync-per-commit
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≈220µs each — the gap iteration 23 exists to close).
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- reads/queries ≈1.1–1.3M ops/s at p50 1µs since the read-path index
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slice (2026-08-22, engine `wo_idx_probe` + emitter index selection) —
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up from ≈1.5k/s at p50 600µs when point lookups walked every slab
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(~×850). mixread 89k ops/s single-shard, ~1.9k multi-shard (was
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1,280 / 21): the RPC round-trip is now the visible cost, as designed.
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- msgrate ≈13M msgs/s same-heap vs ≈2.4M cross-shard (the mutex-inbox
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number, stage-2 deviation 4).
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- Tolerance policy lives in the DRIVER (`tolerance_for`), not hand-edits
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— a baseline refresh regenerates it: mix*/sN/read/query 50%
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(scheduling + µs-scale jitter), rest 15%; latency floors
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`max(4×value, 100µs)` — the tripwire means "µs became ms".
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## The gate must bite (proven 2026-08-21)
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`scripts/db-bench.py --check <results.json>` evaluates a recorded run:
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the real results pass 74/0; a doctored copy FAILS on exactly the
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doctored metrics — use a 15%-class metric (seed) halved plus a
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50%-class metric (read) quartered, so both tolerance classes prove they
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bite. Re-run the smoke after any gate or policy change.
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