# 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 system tables** `__manifest`, `_graph_commits`, and `_graph_commit_actors` (RFC-013 step 2), which accumulate one fragment per commit (the actor table only on the authenticated write path, where every commit carries an actor) and otherwise make every write's metadata scan grow with history. These take a simpler path than data tables: they are not `__manifest`-tracked (readers open them at their latest version), so compaction just advances their 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.) They appear in the returned stats under `table_key` `"__manifest"` / `"_graph_commits"` / `"_graph_commit_actors"` (the latter two only when present). They are **not yet covered by `cleanup`**, so their 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.