shoney.arickathil
a8829232dc
- target 1: write path (update-through-query re-probe, triple index walk, per-field encode, whole-row WAL update record) — re-measure after 23, then decide - targets 2-4 recorded with owners (DB-RPC by design/24, mutex inbox /31, fsync bound /23) - board pending + comparison README link the register Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
40 lines
2 KiB
Markdown
40 lines
2 KiB
Markdown
# go-sqlite — the comparison harness
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Go (`database/sql` + mattn/go-sqlite3, cgo) mirroring
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`docs/examples/db-bench`'s schema and modes line-for-line, so the
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numbers align column-for-column. Not a gate — a reference point;
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SQLite is the honest peer (embedded, single-writer, WAL, same
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durability knob).
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Run: `go build -o go-sqlite . && ./go-sqlite ram 20000` /
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`./go-sqlite durable 20000 <ext4-dir>` — a tmpfs dir makes fsync free
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and the durable numbers a lie (measured: 122k/s on /tmp vs 3.1k/s on
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ext4; the campaign's own trap, re-confirmed).
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## Measured 2026-08-22 (N=20k, same machine, ext4, single-shard vs single-conn)
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| metric | writeonce | Go+SQLite | ratio |
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| --- | --- | --- | --- |
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| ram seed inserts/s | 245,188 | 296,965 | sqlite ×1.2 |
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| ram read ops/s (p50µs) | 1,097,574 (1) | 429,645 (2) | **wo ×2.6** |
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| ram query ops/s | 989,609 | 154,559 | **wo ×6.4** |
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| ram write ops/s | 195,465 | 380,069 | sqlite ×1.9 |
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| durable seed inserts/s (p50µs) | 4,460 (~220) | 3,113 (241) | **wo ×1.4** |
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| durable write ops/s | 2,324 | 3,257 | sqlite ×1.4 |
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Readings, honestly:
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- **Reads/queries: writeonce wins 2.6–6.4×** — RAM-authoritative rows +
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the index probe answer without page decoding or a bytecode/VM ↔ cgo
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boundary; SQLite pays B-tree page traversal + the cgo call per op.
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- **ram writes: SQLite wins ~1.9×** — writeonce's update path re-runs a
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probe per update (update-through-query) and its insert encodes slots
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per field; SQLite's page write is tight. Registered as target 1 in
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[`docs/plan/perf-targets.md`](../../../docs/plan/perf-targets.md).
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- **durable seed: writeonce wins ~1.4×** (append-only WAL + fdatasync
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vs SQLite WAL frame + FULL sync); durable mixed writes flip back to
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SQLite ×1.4 — the update's extra probe again.
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- Caveats: different languages (Go harness pays ~1µs cgo per op; wo
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pays its interpreter), both are the honest end-to-end app-visible
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cost of their stack. Single connection vs single shard; no
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concurrency comparison here (SQLite has one writer by design).
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