---
id: suite-column-postgres
name: Conformance suite — the postgres column (the SKIP-posture column)
status: completed
depends_on: [store-postgres-construction]
scope: moderate
risk: medium
impact: phase
level: implementation
tags: [wave-4, suite, postgres]
---

## Description

Grow the **postgres column** — the suite's first SKIP-posture column
(README §SKIP posture: SQL-attached factories ride a server; when no
server is reachable the column **skips cleanly** — a skip is not a
failure — and the wave's acceptance requires green **against the
server**). The column runs under `--features postgres` (feature
`postgres`, default-off).

- **Factories** (`tests/conformance/postgres_column.rs`):
  - dual-tier `kv = postgres + large = local` at a column-declared
    threshold and the **test tuning of the window delay (`0` —
    execute-on-next-sweep)**;
  - `kv-only(postgres)` at a column-declared threshold (the rejection
    row's host; threshold materializable per the README's
    configuration contract).
  **The alkstore pg-factory pattern, reused** (`alkstore-postgres`
  tests/contract_suite.rs): a **fresh engine-owned schema per
  `open()`** — unique per call (seeded per tag/pid/time so two factory
  instances never share a schema name, racing opens included), tracked
  per-instance in a schema registry, teardown
  `DROP SCHEMA IF EXISTS … CASCADE` over exactly the schemas the
  instance minted (idempotent, owned — never the shared server's other
  schemas; safe against an abandoned store: `CASCADE` removes
  dependents server-side while the store's pooled connections fail
  closed on next use). Panicking-row-safe — the sqlite column's
  instance-tracks-its-own-site pattern over schemas instead of temp
  dirs.
- **Connection settings ride the environment** — the alkstore harness
  convention: `ALKBLOBS_PG_HOST/PORT/USER/PASSWORD/DB` (db defaulting
  `postgres` if unset), a reachability probe gating the rows (the SKIP
  posture's factory-owner responsibility). **The harness server**:
  dockerized `pglo-poc` (`postgres:16-alpine`) on :15432, db `blobs`,
  user/password `postgres`/`poc` — verified live 2026-10-12; the
  container is long-running in the dev environment (the alkstore
  harness's same server).
- **Mirror the form-independent reference rows** (README §The
  reference row set): INV-1 round-trips (content matrix × both put
  paths, in-body), INV-6 stat discipline, the `NoLivenessSources`/
  `ProtectFailed` abort shapes (form-independent — abort before
  staging), and the kv-only rejection row (threshold-agnostic by
  discovery, unchanged).
- **The durable-schedule sweep rows** — the sqlite column's family
  (README §The schedule-relative reading for SQL-backed columns):
  INV-2 dedup and INV-3 stage hygiene with counts read against the
  staged schedule, the two-sweep exact-count row over the full
  protection set (both tiers, the window observed), the
  sweep-vs-put race across the window delay (execution-time
  re-arbitration), the holder-stages-only lease shape, and INV-5 list
  correctness through durable-schedule outcomes.
- **The dual-tier dispatch rows** mirror the sqlite column's family
  (pure-function routing, threshold boundaries, fall-through per op)
  with the placement oracle adapted by medium: kv entries live as rows
  in the pg schema's `blobs` table, large entries under the local
  root — the oracle distinguishes by medium (an independent
  connection counting the schema's rows vs the root's committed
  files).
- **Virgin-store row**: reads are no-ops on a fresh schema (pool,
  both GC tables, and committed tree all empty) — the constructor
  always ensures the schema (the engine's recorded posture), this row
  being the facade form.
- **Structural factory tests** (the mem/sqlite columns' pattern):
  factory isolation (fresh schema per open, nothing shared — two
  opens never observe one another) and teardown-against-a-panicking-row
  (schemas really dropped).
- **README amendments** (the convention's normative test-side home):
  the postgres rows table in §Columns beyond the reference set; the
  column plan's SKIP-posture note now naming a landed column; current
  state (four columns; the first SKIP-posture column, green against
  the harness server).

## Acceptance Criteria

- [ ] The postgres column green **against the harness server**
      (`pglo-poc`, :15432): the mirrored form-independent reference
      rows + the durable-schedule sweep rows + the dispatch rows + the
      virgin-store row, every row ADR-stamped and traceable to the
      backlog
- [ ] Server-less runs skip cleanly (the reachability probe; the
      default-build gates stay green with the column skipped)
- [ ] Factory isolation + idempotent teardown hold (fresh schema per
      open; `DROP SCHEMA … CASCADE` over exactly the minted schemas;
      teardown safe against a panicking row), structurally exercised
- [ ] README amendments recorded (the postgres rows table; current
      state)
- [ ] `cargo test` (default) green — the column compiles out;
      `cargo test --features postgres` green server-less (skipping)
      and green against the server at acceptance;
      `cargo clippy --all-targets -- -D warnings` and
      `cargo fmt --check` green (default + `--features postgres`)

## References

- tests/conformance/README.md (the conventions this grows against;
  §SKIP posture, §Columns beyond the reference set, §The
  schedule-relative reading for SQL-backed columns)
- tests/conformance/factory.rs (the factory contract this implements)
- tests/conformance/rows.rs (the reference row set being mirrored)
- tests/conformance/sqlite_column.rs (the SQL-backed column pattern —
  the durable-schedule rows' first host)
- /workspace/@alkdev/alkstore/alkstore-postgres/tests/contract_suite.rs
  (the pg-factory pattern reused: fresh schema per open, the schema
  registry, the CASCADE teardown, the env-driven DSN)
- docs/architecture/store-api.md (§Invariants — the test gate)
- docs/architecture/decisions/012-pre-decomposition-consistency-rulings.md
  §6.7 (the schedule the sweep rows assert against)
- docs/architecture/decisions/007-two-kv-engines-sqlite-and-postgres.md
  §5 (the exact-count sweep-outcome gate against dockerized postgres)

## Notes

> Implemented in `tests/conformance/postgres_column.rs` + `main.rs` +
> `README.md` (wave 4, following `suite-column-sqlite` — the
> SQL-backed structural twin — and the alkstore pg-factory pattern).
> Recorded design points, as resolved:
>
> - **Factories as specced** — `DualTierPostgresFactory` (kv = postgres
>   + large = local at the column-declared `TUNED_THRESHOLD` = 1024,
>   window delay `WINDOW_DELAY` = `Duration::ZERO`, the test tuning)
>   and `KvOnlyPostgresFactory` (`KV_ONLY_THRESHOLD` = 1024, the
>   rejection row's host). Both hold the DSN, a schema sequence
>   counter, and the per-instance schema registry (`Mutex<Vec<String>>,
>   poisoned-lock via `unwrap_or_else(|e| e.into_inner())` per
>   convention); `open()` mints `alkblobs_suite_{tag}_{pid}_{nanos}_{seq}`
>   — unique per call, racing opens included — plus a fresh private
>   temp root for the large tier (dual-tier; kv-only needs none),
>   tracked per-instance. Teardown `DROP SCHEMA IF EXISTS "…" CASCADE`
>   over exactly the minted schemas (one admin connection, then the
>   drops) plus `remove_dir_all` over the vended roots (NotFound
>   tolerated) — idempotent, owned, panicking-row-safe.
> - **SKIP posture as specced** — `harness_dsn()` rides
>   `ALKBLOBS_PG_HOST/PORT/USER/PASSWORD/DB` (host required, non-empty;
>   port/user/password/db defaulting to the harness server's values —
>   :15432, `postgres`/`poc`, db `blobs` — the src/postgres.rs engine
>   tests' exact convention, the alkblobs adaptation of the alkstore
>   harness convention), `harness_ready()` probes with a 3 s-timed
>   admin connection, every runner gates on it first, and the skip
>   note prints once per skipped test. The acceptance run below is
>   against the harness server — a skip never substituted.
> - **The medium oracle, adapted by medium** — an independent admin
>   connection per count (`SELECT COUNT(*) FROM "schema".blobs` /
>   `gc_window`) vs the root's committed files; `schema_exists` (the
>   `pg_namespace` probe) instruments the structural teardown
>   assertions.
> - **Rows** — the sqlite column's inventory mirrored point for point
>   (the schedule-relative rows, the dispatch rows with the oracle's
>   medium swapped, the virgin-store row read against a fresh schema,
>   the structural factory tests adapted to schemas: two opens mint
>   distinct schemas and share nothing, teardown-against-a-panicking
>   row really drops the schemas); stamps cite the postgres rows of
>   ADR-007/012 (ADR-007 §5 replacing the sqlite arm's citations).
> - **One cleanup caught in review-of-diff**: the `dual_tier` open
>   tracks the temp *base* dir and constructs the store against
>   `base.join("local-root")` — teardown removes the base directory
>   wholesale (the root's parent), so the site removal is one
>   operation like the sqlite column's.
> - The `pglo-poc` container was already running in the dev
>   environment (verified with `docker ps` before implementation); no
>   environment changes were needed.

## Summary

> Completed 2026-10-12 (wave 4). The postgres column — the suite's
> first SKIP-posture column — landed green against the harness server
> (`pglo-poc`, :15432): 17 conformance tests (the mirrored
> form-independent reference rows — INV-1 round-trips, INV-6 stat
> discipline, the `NoLivenessSources`/`ProtectFailed` abort shapes,
> the kv-only rejection row — the durable-schedule sweep rows (INV-2
> and INV-3 schedule-relative readings, the two-sweep exact-count row
> over the full protection set, the sweep-vs-put race across the
> window delay, the holder-stages-only lease shape, INV-5 list
> correctness), the dispatch rows with the placement oracle adapted to
> the pg medium, and the virgin-store row), every row ADR-stamped and
> traced to the backlog. Factory isolation (fresh schema per open,
> registry-tracked) and idempotent `DROP SCHEMA … CASCADE` teardown
> are structurally exercised (panicking-row-safe; `pg_namespace`
> verified empty after runs — the shared server carries no residue).
> README amended: the postgres rows table in §Columns beyond the
> reference set, the column plan's SKIP-posture note naming the
> landed column, and current state (four columns). Verification:
> `cargo test` (default) 69/19/3 ok — the column compiles out;
> `cargo test --features postgres` 102/36/3 ok green against the
> server, and green skipping server-less (17 skip-noted columns rows;
> default-build gates unaffected); `cargo clippy --all-targets -- -D
> warnings` green (default, `--features postgres`, `--all-features`);
> `cargo fmt --check` green.