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| Author | SHA1 | Message | Date | |
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Ragnor Comerford
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f2b792e0ae
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(feat): compact the internal manifest/commit-graph tables in optimize (#291)
* feat(engine): compact the internal __manifest/_graph_commits tables in optimize
`optimize` iterated node/edge catalog tables only, so the two internal system
tables (`__manifest`, `_graph_commits`) accumulated one fragment per commit and
were never compacted -- making every write's metadata scan O(fragments), which
grows forever on a long-lived graph (RFC-013 step 2).
`optimize_all_tables` now also compacts both internal tables via a new
`compact_internal_table`. They are not catalog-tracked (readers open them at
their latest Lance HEAD), so it is a much simpler path than `optimize_one_table`:
compact in place, no manifest publish (nothing to publish to), no recovery
sidecar (a single atomic Lance commit -- no HEAD-before-publish gap), and no
optimize_indices (they carry no Lance index, only object_id's unenforced-PK
metadata). No application lock: Lance's compact_files auto-retries its Rewrite
against any concurrent writer (the canonical LanceDB pattern; Rewrite vs Append
is compatible, vs Update a retryable same-fragment conflict Lance rebases), and a
coordinator refresh afterwards makes the warm handle observe the compacted HEAD.
Compacts both tables even though Phase 7 (iss-991) will later fold _graph_commits
into __manifest -- a one-call throwaway for the full interim win; __manifest
compaction is also the prerequisite for Phase 7's graph_head contention. Cleanup
(version GC) of the internal tables is deliberately NOT included here: it needs
the Q8 cleanup-resurrection watermark first (deferred).
maintenance.rs: optimize now returns 6 stats (4 data + 2 internal); adds
optimize_compacts_internal_tables (sheds fragments, leaks no recovery sidecar,
graph coherent for reads + strict writes after).
* test(engine): un-ignore the internal-table scan LOCK (step 2 acceptance)
`internal_table_scans_are_flat_in_history` was the RED, #[ignore]'d acceptance
gate staged in PR #288. With internal-table compaction landed, a write's
__manifest/_graph_commits scan is flat in commit-history depth on a compacted
graph (measured __manifest 4->2, _graph_commits 7->3 across depth 10->100, vs the
pre-step-2 RED 34->214 / 29->207). The test now compacts at each depth before
measuring and runs green every-PR.
* docs: RFC-013 step 2 internal-table compaction landed
- invariants.md: close the compaction half of the read-path-rederivation known
gap (optimize now compacts the internal tables; cleanup half still deferred).
- maintenance.md: optimize covers __manifest/_graph_commits (no publish, no
sidecar); not yet in cleanup.
- rfc-013 §9: split step 2 into 2a (compaction, landed) and 2b (cleanup + Q8
watermark, deferred — debated; MTT-overlap + hot-path liability).
- testing.md: the internal-table LOCK is now green every-PR.
* fix(engine): guard absent _graph_commits + always compact internal tables
Addresses PR #291 review findings:
- Greptile (P1): optimize unconditionally opened `_graph_commits` for compaction,
but a graph can validly have none (the coordinator opens it as `Option`, gated on
`storage.exists`, for graphs predating the commit graph). `Dataset::open` on the
absent table errored and failed the whole optimize. Guard the `_graph_commits`
compaction with the same `storage_adapter().exists()` check the coordinator uses;
`__manifest` always exists so it stays unguarded. Regression test
`optimize_tolerates_absent_graph_commits_table` (empty graph so no publish
recreates the table before the guard).
- Cursor (low): the `table_tasks.is_empty()` early return skipped internal-table
compaction for a schema with no node/edge types. Removed it so the internal
tables are compacted regardless of the data-table set.
- Codex (auto-cleanup, P1): documented — `compact_files` commits with a default
`CommitConfig` (no skip_auto_cleanup) and `CompactionOptions` exposes no override,
so on a graph storing an *on* auto_cleanup config the commit would fire version
GC. Both internal tables are created with `auto_cleanup: None`, so new graphs are
safe; the only exposure is pre-fix upgraded graphs, identical to the existing
data-table optimize path, with step 2b's watermark as the comprehensive guard.
Added a comment in `compact_internal_table` recording this.
* fix(engine): retry publish on RetryableCommitConflict (compaction vs publish)
Step 2 compacts `__manifest` with no app-level lock (Lance OCC arbitrates,
validated against LanceDB + the lance-7.0.0 conflict resolver). compact_files'
`Operation::Rewrite` auto-retries 20x (CommitConfig default num_retries=20), so a
live publish usually wins the race and the compaction rebases. But the publish
runs its merge-insert with conflict_retries(0) = one rebase attempt; if the
compaction commits first AND the merge touched a fragment the Rewrite rewrote,
Lance preempts the publish with `Error::RetryableCommitConflict` — a DIFFERENT
variant from the row-level `TooMuchWriteContention` the publisher already retries.
Left unhandled, that surfaces a transient error to the caller, i.e. a maintenance
compaction (physical op) failing a live write (logical op) — invariant 7.
Map `LanceError::RetryableCommitConflict` to a new
`ManifestConflictDetails::RetryableCommitConflict` and treat it as retryable in the
publisher's outer loop (reload fresh state + re-merge), alongside
RowLevelCasContention. `ExpectedVersionMismatch` still propagates (a genuine
expectation break must not be blindly retried). This also hardens multi-process
concurrent writers generally, not just compaction.
Normal publishes are insert-only (new object_ids -> new fragments, disjoint from
rewritten old ones), so the conflict is rare; the guard covers the
same-fragment-update edge and multi-process writers. Unit tests in publisher.rs
pin the mapping + the retry-predicate contract.
* revert: publisher RetryableCommitConflict handling (it was the wrong side)
Reverts
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Ragnor Comerford
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f6d2cc03e3
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write-path cost gate + opener bypass (#288)
* docs(rfc): RFC-013 write-path latency design + index link * perf(engine): open write-path tables directly, bypassing the namespace builder Write opens routed through DatasetBuilder::from_namespace, whose describe_table opened the whole dataset just to return a location and then re-resolved the latest version — an O(commit-depth) double latest-resolution per table open that missed Lance's O(1) version-hint fast path. On an object store this dominated write latency (~70%, RFC-013 section 2.4). TableStore::open_dataset_head_for_write now delegates to the direct opener (open_dataset_head: Dataset::open by URI + checkout_branch, routed through the tracked opener so cost tests can count it; a no-op in production). The manifest already holds every sub-table's location, so the namespace catalog lookup was redundant; ensure_expected_version still validates head == pinned for strict ops. This completes PR #268's open-by-location migration on the write side. With both reads (PR #268) and now writes bypassing it, nothing in production routes through the per-table Lance namespace. The dead open chain (load_table_from_namespace, open_table_head_for_write) is deleted and the StagedTableNamespace contract apparatus is gated #[cfg(test)], mirroring the already-test-only read namespace; __manifest commit coordination (GraphNamespacePublisher) is a separate component and is unaffected. See docs/dev/rfc-013-write-path-latency.md sections 2.4 and 9 (step 3a). * test(engine): write-path cost-budget gate on a shared harness Adds tests/helpers/cost.rs, a store-agnostic cost harness (IoCounts/StagedCounts, measure/measure_with_staged, assert_flat, local_graph/s3_graph) that the read-side warm_read_cost.rs, write_cost.rs, and write_cost_s3.rs share, so the IOTracker / task-local plumbing lives in exactly one place instead of duplicated per test. write_cost.rs (local, every-PR) gates the internal-table scan term flat in commit-history depth (a RED #[ignore]'d LOCK, the acceptance for bringing the internal tables into compaction) plus green guards: a single insert's data writes are bounded, a per-write read-op ceiling fails the moment a round-trip is added, and a keyed insert routes through stage_merge_insert once with no stage_append or vector-index build. write_cost_s3.rs (bucket-gated, rustfs CI) gates the data-table opener term flat across depth — the object-store-RPC phenomenon local FS cannot reproduce, and the red->green proof of the opener bypass. Wired into the rustfs_integration CI job and its path filter. Guards the "hot-path cost is bounded by work, not history" invariant on writes. See docs/dev/rfc-013-write-path-latency.md section 5.1, docs/dev/testing.md. * docs(rfc): RFC-013 step 3a landed; write-skew coupling; cost-gate test map - Section 9: mark step 1 (gate + harness) and step 3a (opener bypass) landed; record the per-table namespace retirement to test-only and the corrected measurement note (the opener win is S3-only; the local data-table growth is the merge-insert/RI fragment scan, a compaction term, not the opener). - Sections 7.1/6/11/5.5/10: correct the cross-table write-skew analysis after a prototype proved the scoped expected-set fix is a no-op against the per-object_id manifest (disjoint writers never share a row, so Lance never conflicts, the publisher never retries, and the expected check is a non-atomic pre-check evaluated once against stale state). The fix needs a shared contention row (Phase-7 graph_head / a minimal head row / commit-time re-validation), so it is coupled to that row, not standalone; that contention is load-bearing for correctness, not a drawback. Split the concurrent face (read-set + head) from the sequential face (inbound-RI validation on node removal) -- two different fixes. - testing.md: add write_cost.rs / helpers/cost.rs / write_cost_s3.rs to the test map; document the local-vs-S3 backend split; extend the cost-budget checklist item to the write/open path and point at the shared harness. * test(engine): isolate the opener in the S3 cost gate; fail loud on S3 setup errors Addresses two PR review findings on the bucket-gated write_cost_s3 gate: - The data-table opener was not isolated: `data_reads` also counts the merge-insert/RI scan, which reads O(fragment-count) and so grows with history for a different reason (compaction's domain, not the opener) -- the same term that made the local data-table count grow. The flat assertion would false-RED or misattribute scan growth to the opener on rustfs. Fix: compact (db.optimize) before each measurement so the table holds ~1 fragment, bounding the scan and leaving the opener's latest-version resolution as the only history-varying term. Compaction preserves version history, so the opener still faces a deep _versions/ chain -- the thing under test. - s3_graph used `.ok()?`, so when OMNIGRAPH_S3_TEST_BUCKET was set but the store was down/misconfigured, init/seed failures collapsed to None and the gate skipped + passed vacuously. Fix: skip only when the bucket env var is absent; once it is set, init/seed failures panic (mirrors tests/s3_storage.rs). * test(engine): isolate the S3 opener with a per-prefix IO probe (correct-by-design) Replaces the fixture-bounded isolation (compact-before-measure) from the prior commit with the root fix: a path-classifying ObjectStore wrapper (PrefixCounter) that attributes each data-table read to the opener term (_versions/.manifest) vs the scan term (data/*.lance). IoCounts now exposes data_opener_reads / data_scan_reads, so write_cost_s3 asserts the opener flat *directly* -- no compaction or fixture massaging, and the assertion measures the opener, not the conflated total. Closes the "harness conflates two IO terms" class: any cost test (read or write) can now isolate the opener. PrefixCounter implements only the object_store 0.13 core ObjectStore methods; the convenience surface (get/put/head/...) routes through get_opts/put_opts via ObjectStoreExt's blanket impl, so every read/write is still counted. Validated locally (every-PR) by write_cost::data_table_reads_split_into_flat_opener_ and_growing_scan: opener stays flat (7 -> 3) while scan grows (11 -> 91) and opener + scan == data_total exactly -- proving the classifier and confirming the local data-table growth is the fragment scan, not the opener. warm_read_cost (12 tests) stays green under the shared-harness change. * refactor(tests): remove cost-harness duplication and namespace cfg(test) noise Branch self-review (no behavior change) — pay down three liabilities the write-path work left: - warm_read_cost.rs kept its own probes() (three IOTrackers + a QueryIoProbes + a probe counter) and read raw .stats().read_iops — duplicating the shared helpers::cost harness this branch introduced. Migrated all 12 tests onto measure()/IoCounts; deleted the local probes(). (This also makes IoCounts' version_probes field used rather than dead.) - insert_cost was copy-pasted verbatim into write_cost.rs and write_cost_s3.rs. Hoisted to helpers::cost::measure_insert so the measured write is defined once. - The per-table Lance namespace (namespace.rs) became entirely test-only after step 3a, but was gated with ~22 per-item #[cfg(test)] attributes. Collapsed to a single `#[cfg(test)] mod namespace;` and stripped the per-item attributes; merged the import groups the gating had split. Verified: lib in-source 162 passed; write_cost 4 + warm_read_cost 12 passed; forbidden_apis passed. |