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writeonce/docs/stories/language-runtime-database/done/09-database-engine.md
shoney.arickathil 2a4c304378 docs: stories foldered by state — done/ and refine/ 
- done/ (11): 1, 2, 3, 4, 6, 7, 7b, 9, 9b, 15, 16 — landed iterations
  (9/9b remainders live in the post-12 drain list, not in the files)
- refine/ (8): 9c, 9d, 9e, 9f, 9g, 11, 13, 14 — everything marked
  "no spec yet / brainstorm before planning"
- root keeps: 00-story (index), 05 (partial, plan 8 open), 8/10/12
  (specs or plans exist), 17 (parked, spec+plan approved), 18 (next)
- every cross-reference re-pathed and VERIFIED resolving: board, specs,
  plans, employee-list README, story table, intra-story links (moved
  files' relative links deepened one level; done/7b's 9e pointer now
  crosses to refine/)
- pre-existing dead link noted, not touched: refine/11-fibers.md points
  at docs/plan/exploration/fibers/00-fibers.md which does not exist
  (predates the move)

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-20 04:33:24 +02:00

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Iteration 9 — database engine

Format: product/story-iteration-template. Part of Story — one language, one runtime, one database, one binary.

Goals

  • The language's oldest promise executes on the new runtime: every class is a table. insert and select stop trapping (DB_STUB retires) and run against class-shaped row storage inside the VM's shards.
  • Data survives anything: a typed write-ahead log with ack-after-fsync, parallel boot replay, and a crash battery proving no committed row is ever lost and no half-applied transaction ever visible.

Acceptance Criteria

  • What to achieve?
    • Given a class annotated @table and a method inserting rows,
    • when the method runs,
    • then the insert is WAL-logged before acknowledgment, visible to subsequent select, and the pricing fixture that previously trapped DB_STUB now passes with real data.
  • What to achieve?
    • Given kill -9 at arbitrary points during committed writes,
    • when the process reboots and replays,
    • then every acknowledged commit is present, no unacknowledged partial write is visible, and replay across shards completes without manual steps.
  • What to achieve?
    • Given a @unique field and a duplicate insert,
    • when it executes,
    • then the insert traps with the unique-violation code and secondary indexes remain consistent (maintained only through the engine's row choke points).

Out Of Scope

  • Cypher/document query paradigms and LIVE subscriptions (the query layer's later phases; prototypes/wo-db stays the reference).
  • Cross-shard 2PC transactions; Postgres mirroring (exists on the Rust side; ports after parity).

Info

  • Doctrine: RAM is authoritative; the WAL makes it durable; indexes drift unless writes go through the row API — the Rust runtime learned this lesson, the C engine enforces it.
  • The wo-db overlap manifest keeps the C++ prototype and this engine answer-compatible where features overlap.
  • Ownership/GC analysis (2026-08-15): the engine and the VM heap are two memory worlds crossed only by copy — rows store no VM pointers, GC-managed values in stored fields are a compile error, and everything a query returns is copied out — so the collector never traces rows and the engine never counts references. The full analysis (row views as borrows without a runtime net, cursor stability, GC-pause interaction) lives in the 9b design's section 6: 2026-08-15-table-relations-query-design.md.

Proposed Solution

  • Execute the existing plan: docs/superpowers/plans/2026-08-01-db-engine-binding.md (class-shaped row slabs with a choke-point row API, typed WAL + parallel replay + crash battery, insert execution, doctrine-enforced indexes + @unique trap, select subset, db corpus).