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353c0c876a
* test(lance): pin force_delete_branch surface guard
Pin the Lance 6.0.1 force_delete_branch behavior the branch-delete
single-authority redesign relies on: plain delete_branch errors on a
missing ref, force_delete_branch removes an existing forked branch, and
the local-store quirk where force_delete on a fully-absent branch still
errors (worked around by the upcoming TableStore::force_delete_branch).
Re-pin the docs/dev/lance.md alignment stanza (9 guards; 4 runtime).
* feat(storage): add force branch-delete to TableStore + CommitGraph
Add TableStore::force_delete_branch and CommitGraph::force_delete_branch
(idempotent: tolerate an already-absent branch via Lance RefNotFound /
NotFound), plus CommitGraph::list_branches for the cleanup reconciler to
diff against the manifest authority. RefConflict (referencing
descendants) is still surfaced. Unused until the branch-delete rewire.
* test(maintenance): red — cleanup reconciles orphaned branch forks
Forge a Lance branch on the Person table that the manifest never
references (a zombie fork from an incomplete prior delete) and assert
cleanup reclaims it while leaving main intact. Fails today: cleanup does
not yet reconcile orphaned forks. Goes green with the next commit.
* fix(maintenance): reconcile orphaned branch forks in cleanup
Add reconcile_orphaned_branches: force_delete_branch every per-table and
commit-graph Lance branch absent from the manifest branch set (the
authority), children-before-parents. Folded into cleanup_all_tables,
runs before version GC. Idempotent and authority-derived; no-ops once
nothing is orphaned, and would harmlessly find nothing if a future Lance
atomic multi-dataset branch op prevented orphans. Adds TableStore::list_branches
and exposes graph_commits_uri(pub crate). Turns the maintenance red test green.
* test(failpoints): red — branch_delete partial failure converges
Add the branch_delete.before_table_cleanup failpoint hook (inert without
the feature) and a regression test: a cleanup-step failure after the
manifest authority flip must leave branch_delete returning Ok, the branch
gone, the orphan stranded, then reclaimed by cleanup, and the name
reusable. Fails today: cleanup_deleted_branch_tables propagates the error
as a hard failure. Goes green with the next commit.
* fix(branch): best-effort fork reclaim after the manifest flip
Make branch_delete treat per-table forks and the commit-graph branch as
derived state reclaimed best-effort with force_delete_branch after the
manifest authority flip. A reclaim failure (transient error, or the
branch_delete.before_table_cleanup failpoint) is logged via tracing::warn
and swallowed: the branch is already gone and the cleanup reconciler
converges the orphan. cleanup_deleted_branch_tables no longer returns an
error or blocks the call. Turns the partial-failure recovery test green.
* test(failpoints): red — recreate over orphaned fork is actionable
After a partial-failure delete leaves a fork orphaned, recreating the
branch name and writing to the previously-forked table before cleanup
runs currently surfaces the opaque ExpectedVersionMismatch ("stale view
... expected manifest table version N"). Assert instead a clear error
pointing the user at cleanup. Goes green with the next commit.
* fix(branch): actionable orphan-collision error in fork_branch_from_state
When a fork's create_branch collides with an existing target ref, reuse
it only if its head matches source_version (a legitimate concurrent
first-write). A version mismatch means a zombie fork from an incomplete
prior delete: return a manifest_conflict pointing the user at
`omnigraph cleanup`, instead of the opaque ExpectedVersionMismatch.
Turns the recreate-over-orphan red test green.
* docs(invariants): single-authority branch-lifecycle + Lance forward-compat
Record branch delete in the Current Truth Matrix: manifest is the single
authority flipped atomically first, per-table forks + commit-graph branch
are derived state reclaimed best-effort with the cleanup reconciler as
backstop, and reusing a name whose reclaim failed surfaces an actionable
error. Note the reconciler is authority-derived and degrades to a no-op
under a future Lance atomic multi-dataset branch op, the same shape as
invariant 7.
* test(failpoints): red — cleanup isolates a single-table failure
Add the cleanup.table_gc failpoint hook (inert without the feature) and
an error: Option<String> field on TableCleanupStats (mechanical, always
None for now). Regression test: a one-shot version-GC failure for one
table must not abort the whole cleanup — assert cleanup still succeeds,
surfaces the failure per-table in stats, and the independent reconcile
pass still reclaimed an orphan. Fails today: the version-GC collect
aborts on the first table error. Goes green with the next commit.
* fix(maintenance): fault-isolate cleanup per table
Make the cleanup sweep do as much as it can and converge on re-run
instead of aborting wholesale on one table's transient error
(invariant 13). The version-GC loop now records a per-table failure on
its stats row (error: Some) and logs it rather than collecting into a
Result that aborts; reconcile_orphaned_branches isolates per-table and
commit-graph failures into BranchReconcileStats.failures. The CLI reports
any failed tables and tells the user to rerun cleanup. Addresses the
Devin review finding. Turns the single-table-failure test green.
* test(failpoints): red — branch_create heals commit-graph zombie + is atomic
Add the branch_delete.before_commit_graph_reclaim failpoint hook and two
regression tests: (a) recreating a name whose delete left a commit-graph
zombie must succeed (today it dies on Lance's internal Clone error), and
(b) branch_create must roll back the manifest branch when the derived
commit-graph branch fails (today it leaves the manifest branch created
while returning Err). Both fail now; green with the next commit. The
existing branch_create_failpoint_triggers test still passes.
* fix(branch): make branch_create atomic + heal commit-graph zombie
branch_create now flips the manifest authority first, then creates the
derived commit-graph branch in create_commit_graph_branch, force-dropping
any orphaned commit-graph ref left by an incomplete prior delete (the
manifest branch is fresh, so a same-named commit-graph branch is provably
a zombie). If commit-graph creation fails, the manifest branch is rolled
back so the name never half-exists. Addresses the Codex review finding.
Turns the two branch_create red tests green; existing tests unaffected.
* test(failpoints): red — fork collision misclassifies live concurrent fork
Add the fork.before_classify failpoint hook and a concurrency test: when
a concurrent first-write legitimately wins the fork race, the loser must
get a retryable refresh-and-retry, not the misleading run-cleanup orphan
error. Today the version-comparison misclassifies the live fork as an
orphan (the Cursor finding). Goes green with the next commit.
* fix(branch): manifest-arbitrated fork-collision classification
Classify a fork collision by the manifest authority instead of comparing
Lance branch versions. Before forking, open_owned_dataset_for_branch_write
re-reads the live manifest: if the table is already forked on the active
branch, a concurrent first-write won and the loser gets a retryable
refresh-and-retry (not a misleading orphan error). fork_branch_from_state
no longer guesses from versions — a create collision past that check is
an orphan, so it returns the actionable cleanup error. Addresses the
Cursor finding; turns the live-concurrent-fork test green, zombie path
unchanged.
* test(failpoints): close branch-lifecycle test gaps
Three coverage additions for the branch-delete work (behavior already
correct; these lock it in and catch regressions):
- cleanup_isolates_reconcile_failure: inject a force-delete failure into
the reconcile loop (new cleanup.reconcile_fork hook) and assert the
sweep continues + converges on re-run. Directly covers the reconcile
loop the Devin finding was about (previously only version-GC was).
- cleanup_reclaims_orphaned_commit_graph_branch: forge a commit-graph
orphan via the delete reclaim failpoint and assert cleanup's
reconcile_commit_graph_orphans drops it (previously untested).
- fork_collision_with_live_concurrent_fork_is_retryable: replace the
fixed 300ms sleep with a deterministic readiness signal (cfg_callback +
compare_exchange atomics) so the two-writer ordering can't flake.
Full failpoints suite 31/0.
63 lines
5.5 KiB
Markdown
63 lines
5.5 KiB
Markdown
# Branches, Commits, Snapshots
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## L1 — Lance per-dataset branches
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Lance supports branching at the dataset level: a branch is a named lineage of versions, and `fork_branch_from_state(source_branch, target_branch, source_version)` creates a copy-on-write fork.
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## L2 — Graph-level branches
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OmniGraph builds *graph branches* on top by branching every sub-table coherently:
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- `branch_create(name)` / `branch_create_from(target, name)` — disallowed name `main`; fails if branch exists; ensures the schema-apply lock is idle. Atomic and authority-first like `branch_delete`: it flips the `__manifest` branch (authority), then creates the derived commit-graph branch, force-dropping any orphaned commit-graph ref left by an incomplete prior delete (the manifest branch is fresh, so a same-named commit-graph branch is provably a zombie). If commit-graph creation fails, the manifest branch is rolled back so the name never half-exists.
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- `branch_list()` — returns public branches, **filters internal** `__run__…` and `__schema_apply_lock__` prefixes.
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- `branch_delete(name)` — refuses if there are descendants or active runs on the branch. The manifest is the single authority for branch existence: deletion flips the `__manifest` branch ref first (one atomic op), after which the branch is gone from every snapshot. The owned per-table forks and the commit-graph branch are derived state, reclaimed best-effort with `force_delete_branch` after the flip. A failure during that reclaim (transient object-store error) does not fail the call or block the authority flip; the leftover forks are unreachable orphans that the [`cleanup`](maintenance.md) reconciler converges. One consequence: if a delete's best-effort reclaim fails, reusing that branch name before the next `cleanup` surfaces a clear error pointing at `cleanup` (the stale fork would otherwise collide on first write).
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- **Lazy forking**: a branch only forks a sub-table when that sub-table is first mutated on it. Pure-read branches share fragments with their source. A fork collision is classified by the manifest authority, not by Lance branch versions: if the live manifest already records the fork on the active branch, a concurrent first-write won and the caller gets a retryable "refresh and retry"; if the manifest does not, a physical branch there is an orphan and the caller is pointed at `cleanup`.
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- `sync_branch(branch)` — re-binds the in-memory handle to the latest head of the branch.
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## L2 — Commit graph (`db/commit_graph.rs`)
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In-memory shape of a graph commit:
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```
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GraphCommit {
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graph_commit_id: ULID,
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manifest_branch: Option<String>,
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manifest_version: u64,
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parent_commit_id: Option<String>,
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merged_parent_commit_id: Option<String>, // populated for merge commits
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actor_id: Option<String>, // joined in-memory from _graph_commit_actors.lance, NOT a column on _graph_commits.lance
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created_at: i64 (microseconds since epoch),
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}
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```
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Storage is split across two Lance datasets (both with stable row IDs):
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- `_graph_commits.lance` — every column above *except* `actor_id`.
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- `_graph_commit_actors.lance` — optional separate `(graph_commit_id, actor_id)` map, created on demand. The `actor_id` field above is populated by joining this dataset in-memory at load time.
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Notes:
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- Every successful publish (load / change / merge / schema_apply) appends one commit.
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- Merge commits have two parents; linear commits have one.
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- API: `list_commits(branch)`, `get_commit(id)`, `head_commit_id_for_branch(branch)`.
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## L2 — Snapshots & time travel
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- `snapshot()` — current snapshot for the bound branch; cached.
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- `snapshot_of(target)` — snapshot at a `ReadTarget` (branch | snapshot id).
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- `snapshot_at_version(v: u64)` — historical snapshot from any manifest version.
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- `entity_at(table_key, id, version)` — single-entity time travel without building a full snapshot.
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- A `Snapshot` is a `(version, HashMap<table_key, SubTableEntry>)` — cheap to build, snapshot-isolated cross-table reads.
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## L2 — Internal system branches
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Filtered from `branch_list()` but visible to internals:
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- `__schema_apply_lock__` — serializes schema migrations.
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- `__run__<run-id>` — legacy from the pre-v0.4.0 Run state machine (removed in MR-771). The branch-name guard predicate `is_internal_run_branch` is kept as defense-in-depth so users cannot create a branch matching the legacy prefix; the filter will be removed once production legacy branches are swept (MR-770).
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## L2 — Recovery audit trail
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The four migrated writers (`MutationStaging::finalize`, `schema_apply`, `branch_merge`, `ensure_indices`) protect their multi-table commits with a sidecar at `__recovery/{ulid}.json` written before Phase B and deleted after Phase C. The next `Omnigraph::open` (gated on `OpenMode::ReadWrite`) runs the recovery sweep in `crates/omnigraph/src/db/manifest/recovery.rs`: classify per-table state, decide all-or-nothing per sidecar, roll forward / back, record an audit row.
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Audit rows live in `_graph_commit_recoveries.lance` (sibling to `_graph_commits.lance`) and reference the commit graph by `graph_commit_id`. The linked recovery commit is identified by that same `graph_commit_id`, and `actor_id="omnigraph:recovery"` is stored in `_graph_commit_actors.lance` (joined by `graph_commit_id`) — `_graph_commits.lance` itself does not carry the `actor_id` column. To find recoveries for a specific original actor: `omnigraph commit list --filter actor=omnigraph:recovery`, then join to `_graph_commit_recoveries.lance` by `graph_commit_id` to read `recovery_for_actor`. Schema: see `crates/omnigraph/src/db/recovery_audit.rs`.
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