omnigraph/docs/user/operations/maintenance.md
Ragnor Comerford 7779b72446
feat(engine): retire commit-graph tables (#311)
* docs(dev): write-latency roadmap (validated cost model + layered fix)

Records the validated 6-LIST warm-write cost model, the two root causes
(un-GC'd _versions/; re-resolving latest by listing), and the layered fix
(GC + capture-once reuse), plus how commit-graph-table retirement feeds in.
Linked from docs/dev/index.md next to the RFC-013 docs.

* feat(engine)!: strand storage versioning — one internal-schema version, no in-place migration

Set MIN_SUPPORTED == CURRENT == 4: this binary reads exactly one `__manifest`
internal-schema version and refuses any older graph on open with a
rebuild-via-export/import message, instead of migrating it in place. Storage
format changes become a deliberate cutover, not a permanently-carried in-place
migration — the pre-release "complexity must be earned" contract.

Delete the entire in-place migration apparatus and everything that existed only
to support it: the `migrate_vN` arms + dispatcher + stamp-bump helpers + the
schema-version-floor tripwire; `migrate_on_open` (both open modes now refuse);
the legacy `_graph_commits.lance` readers + the v3 test fixtures + migration
tests + `migration.v3_to_v4.*` failpoints + the two surface guards that pinned
Lance variants only the migration matched on; and `state::merge_lineage_rows`.
Keep `read_stamp` / `stamp_current_version` / `set_stamp` /
`refuse_if_stamp_unsupported` — the seam a future one-shot converter plugs into.

`load_commit_cache_for_branch` now reads the `__manifest` projection
unconditionally (sub-v4 graphs are refused at open). Adds
`sub_current_graph_is_refused_on_open_with_rebuild_hint`.

The commit-graph TABLES are still created/used as branch-ref ledgers — their
retirement (CommitGraph -> pure `__manifest` projection) is the next commit.

BREAKING CHANGE: a graph created by omnigraph <= 0.7.2 (internal schema v3) is
refused on open. Rebuild it: `omnigraph export` with the old release, then
`omnigraph init` + `omnigraph load` with this one. Data, vectors, and blobs are
preserved; commit history and branches are not.

* feat(engine)!: retire `_graph_commits.lance` / `_graph_commit_actors.lance` — CommitGraph is a pure `__manifest` projection

Since RFC-013 Phase 7, graph lineage lives in `__manifest` (`graph_commit` /
`graph_head` rows) and branch authority is `__manifest` (branch create forks it
first). The two commit-graph datasets were vestigial: `_graph_commit_actors.lance`
was never written or read; `_graph_commits.lance` carried zero commit rows and
only mirrored the manifest's branch refs (a deny-list "parallel copy"). Retire
both.

- `CommitGraph` collapses to a pure projection: drops its Lance dataset handles
  (`dataset`/`actor_dataset`) and all branch methods; `open`/`open_at_branch`/
  `refresh`/`init` open NO dataset, building the cache from
  `ManifestCoordinator::read_graph_lineage_at`. Removes ~1.4s of cold-open
  dataset opens.
- `graph_coordinator`: `commit_graph` is now non-`Option` (always a valid
  projection). `branch_create`/`branch_delete` go through `ManifestCoordinator`
  only — a single atomic op, replacing the two-step manifest-fork +
  commit-graph-fork + rollback. Deleted `create_commit_graph_branch`,
  `reclaim_commit_graph_branch`, `ensure_commit_graph_initialized`, and every
  `storage.exists(_graph_commits.lance)` gate.
- `optimize`: dropped `reconcile_commit_graph_orphans` and the two tables from
  the internal-table compaction set (now `__manifest` only).
- `instrumentation`: `INTERNAL_TABLE_DIRS` no longer lists the two tables.
- Fresh graphs create neither table; `lineage_projection.rs` now asserts both
  `.lance` dirs are absent. Deleted the obsolete commit-graph-branch-race
  failpoint tests + their failpoint names, and updated the `maintenance`
  optimize tests (one internal table, not three).

Review-pass fixes folded in:
- Removed two stale `omnigraph.rs` in-source tests the prior run missed (a
  disk-full link failure masked them): one asserting `open` probes
  `_graph_commits.lance` (the exists-gate this commit removes) — it was masked
  earlier by a disk-full link failure.
- Corrected src comments referencing deleted code (`migrate_v3_to_v4`,
  `append_commit`/`append_merge_commit`, the three-internal-table list,
  the `_graph_commits` reconcile owner) in publisher/recovery/optimize/recovery_audit.
- Narrowed `set_stamp_for_test` to `cfg(test)` (its only caller is the refusal
  test) — removes a dead-code warning in the failpoints build.

Branch create/delete atomicity improves (single atomic `__manifest` op). No
behavior change for reads or branches.

Follow-up (separate commit): the now-always-0 `IoCounts::commit_graph_reads` test
counter + its `IOTracker`, threaded through ~11 cost-test files.

* feat: surface the internal-schema (storage-format) version to operators

After stranding storage versioning (a sub-v4 graph is refused on open), operators
could only discover the storage-format version by hitting a refusal. Surface it:

- `omnigraph version` prints an `internal-schema <N>` line (the binary's CURRENT
  storage-format version).
- `omnigraph snapshot` includes `internal_schema_version` — the GRAPH's per-branch
  on-disk stamp, read via the new `Omnigraph::internal_schema_version_of`.
- `GET /healthz` includes `internal_schema_version` (server-scoped: the binary's
  CURRENT, alongside `version`/`source_version`).

Wire: re-expose `INTERNAL_MANIFEST_SCHEMA_VERSION` as `pub` on `db::manifest`;
add `internal_schema_version: u32` to `SnapshotOutput` + `HealthOutput`;
`snapshot_payload` takes the per-graph version (the `Snapshot` does not carry it),
threaded through the embedded CLI + server snapshot callers. `openapi.json`
regenerated (two added int32 properties). Extends the existing healthz / snapshot /
version tests.

* docs(engine): gate internal-schema version at the graph level; record the per-branch read gap

PR reviewers flagged that the open path validates only main's internal-schema stamp, so a branch read could decode a branch stamped outside this binary's range. The stamp is a graph-wide storage-format property (the upgrade path is a whole-graph export/import), so with one binary version every branch is always CURRENT; divergence needs concurrent multi-version writers, an unsupported topology already in one-winner-CAS territory. Gating per-branch would add a second __manifest open per non-main branch read to defend a state we do not support, unearned complexity that regresses the warm-read budget.

Keep the graph-level gate, document it at the code site (refuse_if_internal_schema_unsupported), and record the read-only residual hole as a known gap in invariants.md to close only when multi-version write topologies become supported. Also clarify the sub-floor rebuild message to say "export with the older omnigraph binary that created it."

No behavior change: HEAD already gated at the graph level.

* test(cost): remove the dead commit_graph_reads IO counter

Phase B retired _graph_commits.lance / _graph_commit_actors.lance, so no commit-graph dataset is opened and the commit_graph IOTracker term is structurally always 0. Remove IoCounts::commit_graph_reads, its total_reads() term, the commit_graph IOTracker in OpProbes, and the now-dead commit_graph_wrapper field on QueryIoProbes (it had no accessor — nothing ever attached it). Drop the 7 trivially-true assert_eq!(commit_graph_reads, 0) checks in warm_read_cost.rs and the debug-print refs in write_cost{,_s3}.rs.

Lineage and actor rows now live in __manifest (RFC-013 Phase 7), so the internal_table_scans_are_flat_in_history gate folds into the single manifest_reads flat-assertion — the manifest scan already covers them. Harness-only; no production runtime impact.

* docs: align with the commit-graph retirement + strand storage versioning

Update the always-loaded and user-facing docs to match the landed state: graph lineage lives in __manifest, the _graph_commits.lance / _graph_commit_actors.lance tables are retired, and storage is strict-single-version (no in-place migration — a sub-CURRENT graph is refused with an export/import rebuild).

Fixed stale claims in invariants.md (the migration/atomicity known-gap entry, the Truth Matrix branch-delete row, the read-path/optimize internal-table scope), lance.md (the migrate_v1_to_v2 PK bullet now reflects init-time set; removed the two deleted v3->v4 migration surface guards), testing.md (dropped the deleted migration failpoint tests; manifest-only internal-table term), writes.md (rewrote the Migration-code section to the strand model), storage.md / maintenance.md / constants.md (retired tables out of the layout, internal-table compaction scope, and the constants cheat-sheet), and AGENTS.md. Marked the retirement DONE in the RFC-013 handoff/roadmap and banner-noted the historical RFC analysis.

Added docs/user/operations/upgrade.md (the export/import rebuild recipe) and docs/dev/versioning.md (the four-axis compatibility policy: release lockstep / wire additive / storage strict-single-version / Lance pinned), cross-linked from the audience indexes and the AGENTS.md topic map, and rewrote the in-progress v0.8.0 release note for the strand model + version surfacing. check-agents-md.sh passes (65 links, 62 docs).

* test(manifest): cover the v3-refusal→export/import rebuild cycle and branch stamp inheritance

Two coverage additions from PR review (P1):

(a) sub_current_graph_is_refused_then_rebuilt_via_export_import — the full operator narrative in one flow: load → export → a sub-CURRENT graph (stamp rewound below CURRENT) is refused with the export nudge → fresh init + load(export) → data present and the rebuilt graph opens. The refusal is stamp-only (read before any data), so a stamp-rewound graph is a faithful stand-in for a real older-release graph without a second binary; vector/blob fidelity stays covered by tests/export.rs.

(b) branch_inherits_main_internal_schema_stamp — proves a branch cannot diverge from main's stamp under single-binary operation (create_branch forks main's __manifest, the publisher does not re-stamp), which is why the graph-level (main-only) stamp gate is sufficient for supported inputs. A divergent branch stamp needs concurrent multi-version writers, the unsupported topology recorded as a known gap.
2026-06-28 16:49:49 +02:00

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Markdown

# Maintenance: Optimize, Repair & Cleanup
**Addressing.** `optimize`, `repair`, and `cleanup` are **direct** (storage-native) CLI commands: they run with direct storage access against a positional `file://`/`s3://` URI or **`--cluster <dir|s3://…> --graph <id>`** (which resolves the graph's storage URI from the served cluster state, so you needn't know the `<storage>/graphs/<id>.omni` layout). They never run through a server, and reject `--server` or a remote (`http(s)://`) URI with a declared error. There are no server routes for them by design — to maintain a server-backed graph, run them out-of-band against the graph's storage URI. See the *Command capabilities* section of [cli-reference.md](../cli/reference.md).
## `optimize` — non-destructive
- Compacts every node + edge table on `main`, then reindexes them, then **publishes the resulting version to the `__manifest`** so the manifest's recorded version tracks the compacted-and-reindexed state. Reads pin the manifest version, so without this publish the work would be invisible to readers *and* would break the version precondition of the next schema apply / strict update/delete ("stale view … refresh and retry"). The publish advances the graph version (a system-attributed commit) only for tables that actually changed.
- Rewrites small fragments into fewer large ones; old fragments remain reachable via older versions until `cleanup` runs.
- **Also compacts the internal `__manifest` table** (RFC-013 step 2), which accumulates one fragment per commit — it now carries the graph lineage and actor rows inline (RFC-013 Phase 7: `graph_commit` / `graph_head` rows), so on the authenticated write path every commit's actor lands here too — and otherwise makes every write's metadata scan grow with history. (The `_graph_commits.lance` / `_graph_commit_actors.lance` tables are retired, so there is no separate lineage table to compact.) It takes a simpler path than data tables: `__manifest` is read at its latest version, so compaction just advances its version in place — **no manifest publish and no recovery sidecar**. (The sidecar-free property is not because it is one commit — `compact_files` can emit a `ReserveFragments` commit before the `Rewrite`, and the auto-cleanup strip below is a further commit — but because every one of those commits is content-preserving and the table is read at its latest version, so a crash at any point leaves it readable and content-identical and the next `optimize` re-plans.) It appears in the returned stats under `table_key` `"__manifest"`. It is **not yet covered by `cleanup`**, so its version chain still grows until the cleanup half lands (it requires a cleanup-resurrection safeguard first); run `optimize` on a cadence to keep per-write metadata scans flat.
- **`optimize` is non-destructive by construction — it never garbage-collects versions, on any table (data or internal).** Compaction rewrites fragments and advances the version; old versions stay reachable until you run `cleanup`. This holds even for a graph created by an older binary that stored an on-by-default Lance `auto_cleanup` hook: `compact_files` / `optimize_indices` commit with the hook enabled and expose no skip override, so before compacting **any** table `optimize` strips its stale `lance.auto_cleanup.*` config first, so Lance's commit-time GC hook cannot fire and silently prune `__manifest`-pinned versions. (Graphs created by current binaries store no such config; the strip is the upgrade-path safety net.) The internal-table path additionally tolerates a concurrent live writer: it runs a **bounded** rebase-and-retry, so transient contention does not fail the operator's `optimize` or the live write — but sustained contention past the retry budget surfaces a loud conflict error rather than looping forever (bounded and observable, not a silent give-up). The data-table path holds the per-table write queue while it compacts, so it does not contend with mutations on that table in the first place.
- **Reindex (index coverage maintenance).** A scalar/FTS/vector index only covers the fragments it was built over. Rows appended after the index was built (e.g. by `load --mode merge`, whose commit does not rebuild an already-existing index) are scanned unindexed, and compaction itself rewrites fragments out of an index's coverage. `optimize` runs Lance's incremental `optimize_indices` after compaction to fold those fragments back in (a delta merge, not a full retrain), restoring full coverage so equality/range/traversal predicates stay index-accelerated. This is why a table with **no compaction work but stale index coverage still commits** a new version under `optimize`. Run `optimize` on a cadence at least as frequent as your freshness window so recently-loaded rows do not linger in the unindexed flat-scan tail.
- **Create declared-but-missing indexes (the index reconciler).** `@index`/`@key` declares intent; `schema apply` records it but builds nothing, and `load`/`mutate` defer a column that cannot be built yet (a `Vector` column with no trainable vectors). `optimize` materializes any such declared-but-unbuilt index over the compacted layout — so it is the convergence path for an `@index` added after data exists, or a vector index whose embeddings arrived via a later `embed`. A column still not buildable (no vectors yet) is reported on the table's stat as `pending_indexes` (visible in `--json`), not treated as a failure; the next `optimize` retries. So `optimize` is the single operator-facing index reconciler: it compacts, restores coverage, **and** builds declared-but-missing indexes.
- Each table's compact→reindex→publish serializes with concurrent mutations on the same table. A crash mid-operation is recovered automatically on the next open (both compaction and reindex are content-preserving, so roll-forward is always safe).
- **Requires a recovered graph.** `optimize` refuses (errors) when a pending crash-recovery operation is present — operating on an unrecovered graph could publish a partial write that recovery would roll back. Reopen the graph to run recovery, then re-run `optimize`.
- **Uncovered drift is skipped, not interpreted.** If a table's underlying version is ahead of the version recorded in `__manifest` and no crash-recovery record covers that movement, `optimize` reports `skipped: DriftNeedsRepair` with the manifest/head versions and leaves the table untouched. Run `omnigraph repair` to classify and explicitly publish that drift.
- Bounded by `OMNIGRAPH_MAINTENANCE_CONCURRENCY` (default 8).
- Returns per-table stats: `table_key, fragments_removed, fragments_added, committed, skipped, manifest_version, lance_head_version, pending_indexes` (the last lists any declared `@index` column the reconciler could not build this run, with the reason — e.g. a vector column with no trainable vectors yet).
- **Blob tables are skipped.** A table that declares any `Blob` property is not compacted: it is reported with `skipped: BlobColumnsUnsupportedByLance` (and logged) instead of compacted, and the rest of the sweep proceeds normally. **Reads and writes are unaffected** — only compaction is. Consequence: fragment count and deleted-row space on blob tables are not reclaimed; query results are never affected. A skipped blob table is also **not reindexed** in the same sweep (the skip happens before the reindex step), so its index coverage on appended rows is not refreshed by `optimize` today.
## `repair` — explicit
- Handles **uncovered manifest/head drift**: a table's underlying version is ahead of the manifest pin and no crash-recovery record explains the movement.
- Preview by default. `omnigraph repair --json <uri>` reports each table's `classification`, `action`, manifest/head versions, underlying operation names, and any classification error. `--confirm` publishes only verified maintenance drift; if any suspicious or unverifiable table is refused, the CLI prints the per-table output and exits non-zero. `--force --confirm` also publishes suspicious or unverifiable drift after operator review.
- Classifies drift by reading the table's transaction history from `manifest_version + 1` through the current head. Only fragment-reservation and rewrite (compaction) operations are verified maintenance. Semantic operations such as append, delete, update, merge, or missing transaction history are not auto-healed.
- Publishes repair by advancing `__manifest` to the existing head; it does **not** rewrite data. If the publish succeeds, normal reads and strict writes use the repaired version. If it fails, no new data-side partial state was created.
- Requires a clean recovery state. A pending crash-recovery operation still belongs to automatic recovery, not manual repair.
## `cleanup` — destructive
- Garbage-collects old versions per table.
- Removes versions (and their unique fragments) older than the retention policy.
- Policy options `keep_versions` and `older_than` — at least one is required.
- Returns per-table stats: `table_key, bytes_removed, old_versions_removed, error`.
- **Fault-isolated per table.** A single table's transient failure (version GC or
orphan reclaim) is recorded on that table's stats row (with an `error`) and logged,
and never aborts the healthy tables — cleanup is the convergence
backstop, so it does as much as it can and converges on re-run. The CLI reports
any failed tables; rerun `cleanup` to retry them.
- CLI guards with `--confirm`; without it, prints a preview line.
- **Non-local consent.** Against a non-local target (an `s3://` store/cluster), `cleanup` additionally requires `--yes` on top of `--confirm`: a TTY is prompted, and a non-interactive run (no TTY, or `--json`) refuses rather than destroying. A local (`file://`) target needs only `--confirm`. The same `--yes` gate applies to overwrite `load` and `branch delete`; every maintenance run echoes its resolved target to stderr (suppress with `--quiet`).
- **Recovery floor:** `--keep < 3` may garbage-collect versions that crash recovery needs as a rollback target. Default `--keep 10` is safe.
- **Orphaned-branch reconciliation:** before the version GC, cleanup reclaims any per-table or commit-graph branch absent from the manifest branch list. These orphans arise when a `branch_delete` flips the manifest authority but a downstream best-effort reclaim does not complete (see [branches-commits.md](../branching/index.md)). The reconciler is idempotent (it no-ops once nothing is orphaned), runs regardless of the `keep_versions` / `older_than` values (those gate version GC only), and never reclaims `main` or system-branch forks. Reclaimed forks are logged.
## Tombstones
Logical sub-table delete markers in `__manifest` that exclude a sub-table version from snapshot reconstruction.
## Internal schema migrations
Version evolutions of the on-disk `__manifest` shape are reconciled automatically on the first write under a new binary. An on-disk stamp records the shape; the binary migrates it forward before reading state, and reads are side-effect-free. No operator action is required for in-place upgrades. See [storage.md → Internal schema versioning](../concepts/storage.md) for the full mechanism.
A binary opening a manifest stamped at a version *higher* than it knows about refuses to publish with a clear "upgrade omnigraph first" error — old binaries cannot clobber a newer schema.