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* test(engine): pin the long-lived-handle heal contract for sidecar-covered drift
A Phase B -> Phase C failure (commit_staged advanced Lance HEAD, manifest
publish did not land, recovery sidecar persists) currently wedges every
subsequent staged write on the same engine handle: the commit-time drift
guard rejects with 'run omnigraph repair', but repair itself refuses
while a recovery sidecar is pending, so a long-lived server can only
recover by restart. The documented contract (writes.md 'Long-running
servers', invariants.md invariant 5) says refresh-time roll-forward
closes this residual without restart -- but no write path runs it.
Two red tests pin the intended contract at the write entry points:
a follow-up load (the POST /ingest shape: shared handle, no reopen)
and a follow-up mutation must heal roll-forward-eligible sidecars
in-process and then succeed.
Currently failing with:
table 'node:Company' has Lance HEAD version 2 ahead of manifest
version 1; run `omnigraph repair` before writing
The fix lands in the next commit.
* fix(engine): heal pending recovery sidecars at the staged-write entry points
Close the long-lived-process gap in the recovery protocol: a Phase B ->
Phase C residual (per-table commit_staged landed, manifest publish did
not, sidecar persists) previously recovered only at the next ReadWrite
open or via an explicit refresh() that no production write path called,
so a long-lived server wedged every subsequent write on the commit-time
drift guard until restart.
New recovery::heal_pending_sidecars_roll_forward:
- one list_dir of __recovery/ at write entry (empty -> immediate
return, the steady state), so the per-write cost is one storage list;
- per sidecar, acquires the same per-(table_key, table_branch) write
queues every sidecar writer holds from before write_sidecar until
after delete_sidecar, then re-checks sidecar existence -- this
serializes the heal against live writers instead of rolling an
in-flight sidecar forward from under its writer (which would fail
that writer's publish CAS spuriously). Lock order queues ->
coordinator matches every writer's commit->publish path. This is the
queue-acquisition design recovery.rs and write_queue.rs already
documented for in-process recovery;
- processes in RollForwardOnly mode: the common residual rolls forward
in-process; rollback-eligible sidecars still defer to the next
ReadWrite open (Dataset::restore is unsafe under concurrency).
Wire it into load_as and mutate_as (before the inline delete path can
advance any HEAD), and rebase Omnigraph::refresh onto the same helper
so refresh stops racing live writers' sidecars.
The maintenance entry points (apply_schema_as, branch_merge_as,
ensure_indices) intentionally keep their strict fail-loud preconditions
for now; wiring the same heal there is a follow-up with its own tests.
Turns the previous commit's two red tests green.
* fix(engine): name the right recovery path in the commit-time drift guard
The drift guard's 'run omnigraph repair before writing' advice is a
dead end when the drift is covered by a pending recovery sidecar:
repair refuses while a sidecar is pending. With the write-entry heal in
place, reaching this guard with sidecar-covered drift means the heal
deferred it (rollback-eligible), and the actual recovery path is a
read-write reopen. Distinguish the two classes on the error path only
(one sidecar list, after the conflict is already certain); a listing
failure falls back to the uncovered-drift wording rather than masking
the conflict.
Pinned by extending refresh_defers_rollback_eligible_sidecar_to_next_open
with a write attempt against the deferred sidecar.
* docs: write-entry in-process sidecar heal — contract and coverage
Update the recovery contract docs to match the previous two commits:
invariant 5 now states that the staged-write entry points and refresh
run in-process roll-forward recovery (long-lived processes converge on
the next write, not at restart); writes.md 'Long-running servers'
describes the heal's queue-acquisition concurrency contract, the
improved drift-guard error, and the entry points that intentionally do
not heal yet; testing.md indexes the new failpoint tests; AGENTS.md
capability matrix drops the claim that in-process recovery is entirely
future work (only the rollback path remains with the background
reconciler).
* test(engine): pin the entry heal contract for schema apply and branch merge
Without the write-entry heal, the two maintenance writers do worse than
wedge on sidecar-covered drift -- they proceed and decide its fate
implicitly:
- schema apply re-plans table rewrites from the manifest pin, orphaning
the drifted Phase-B commit (its rows silently vanish from the
rewritten table) while the stale sidecar lingers to misclassify
against the post-apply pins;
- branch merge publishes over the drift, making the failed writer's
commit visible as an unattributed side effect (no recovery audit
row), and leaves the stale sidecar behind.
Two red tests pin the intended contract: both entry points heal the
sidecar first (attributed roll-forward), then run on the converged
state. Currently failing on the stale-sidecar / dropped-rows
assertions; the fix lands in the next commit.
* fix(engine): heal pending recovery sidecars at the schema-apply and branch-merge entries
Extend the write-entry heal to the remaining two write entry points.
Unlike load/mutate (which wedge on the drift guard), these proceeded
over sidecar-covered drift and decided its fate implicitly:
- schema apply re-planned table rewrites from the manifest pin,
orphaning the drifted Phase-B commit -- its rows silently vanished
from the rewritten table -- while the stale sidecar lingered to
misclassify against the post-apply pins;
- branch merge published over the drift, making the failed writer's
commit visible without a recovery audit row, and left the stale
sidecar behind.
Both now run the same queue-serialized roll-forward heal at entry,
before their own sidecar exists, so recovery is attributed (audit row)
and deterministic. ensure_indices stays heal-free: it runs inside the
load / schema-apply flows after their entry heal.
Turns the previous commit's two red tests green. Docs updated in the
same change (invariant 5, writes.md, testing.md, AGENTS.md).
* test(engine): pin Phase A sidecar-write failure semantics
Storage fault-injection matrix, row 1: a sidecar PUT failure (S3
PutObject / fs write) in Phase A. New failpoint recovery.sidecar_write
at the top of write_sidecar -- the single choke point all five sidecar
writers go through -- models the storage error backend-generically.
Also adds the other three storage-fault failpoints used by the
following commits (recovery.sidecar_delete, recovery.sidecar_list,
recovery.record_audit); each is a no-op without the failpoints feature.
Pinned contract: every writer writes its sidecar BEFORE its first
HEAD-advancing commit, so a put failure aborts with zero drift (no
sidecar, Lance HEAD == manifest pin, no rows) and a transient fault
never wedges the graph -- the same handle writes/merges normally once
it clears. Covered for load (the staging writer) and branch_merge (the
multi-table writer, forced onto the RewriteMerged path by diverging
both sides).
* test(engine): pin Phase D delete, list, and audit-append storage-fault semantics
Storage fault-injection matrix, rows 2/3/5, plus the real-backend run:
- recovery.sidecar_delete: a Phase D delete failure (S3 DeleteObject)
must NOT fail the user's write -- the manifest publish already
landed, so the caller's data is durable. The swallowed failure
leaves a stale sidecar; the next write's entry heal consumes it via
the stale-sidecar audit-recovery path (RolledForward, attributed).
- recovery.sidecar_list: a __recovery/ list failure (S3 ListObjectsV2)
is loud at every consumer -- the write-entry heal fails the write
and the open-time sweep fails the open. Silently skipping recovery
over a pending sidecar would be consumer tolerance of drift. Once
the fault clears, open recovers the pending sidecar normally.
- recovery.record_audit: an audit write failure after the
roll-forward's manifest publish aborts that recovery attempt and
keeps the sidecar; re-entry detects the already-published manifest,
records exactly ONE RolledForward audit row, and converges -- the
retry tolerance documented on record_audit, exercised end-to-end.
- s3_load_recovers_after_publisher_failure_without_reopen: the
same-handle heal scenario on a real bucket (gated on
OMNIGRAPH_S3_TEST_BUCKET, skips locally), exercising sidecar
put/list/delete through S3StorageAdapter instead of the local-FS
adapter. CI wiring lands in a follow-up commit.
* test(engine): refuse corrupt recovery sidecars loudly
Storage fault-injection matrix, row 4 (no failpoint needed -- the
corrupt file is written by hand, sibling to the unknown-schema-version
refusal test): a truncated/garbage __recovery/{ulid}.json must be
refused loudly by both the write-entry heal (the write fails naming
the parse error) and the open-time sweep (ReadWrite open fails naming
the file), with the file left on disk for operator inspection.
Read-only opens still work -- the sweep is skipped there.
* test(engine): run the S3 sidecar-lifecycle coverage in CI + document the fault matrix
- ci.yml rustfs_integration: new step running the bucket-gated
failpoints tests (name filter s3_) against the RustFS container, so
sidecar put/list/delete are exercised through S3StorageAdapter on
every storage-affecting PR.
- writes.md: sidecar I/O failure semantics -- Phase A put failure
aborts with zero drift; Phase D delete failure is swallowed (write
already durable) and healed by the next write; list failures are
loud at heal and open; corrupt sidecars are refused with the file
kept for inspection; audit-append failures are retried to exactly
one audit row.
- testing.md: index the storage-fault matrix in the failpoints.rs row
and the new RustFS CI line.
* test(engine): pin read-visibility of acknowledged local if-absent writes
The cluster lib test import_missing_state_creates_state_with_graph_-
observation flakes at ~50% under full-workspace load ('EOF while
parsing a value' reading back the state.json its own import just
acknowledged). Root cause is in the engine's local storage adapter:
write_text_if_absent writes through a buffered tokio::fs::File and
returns when write_all resolves -- which, per tokio's documented File
semantics, means the bytes reached tokio's internal buffer, not the
file. The actual write completes in a background blocking task after
drop, so a caller that acknowledges success and reads the object back
can see an empty or partial file. Under load the window widens; the
red run fails at iteration 0 with 0 of 8192 bytes on disk.
The regression test pins the contract at the adapter boundary: when
write_text_if_absent resolves, the full contents are visible to any
reader; a losing second claim leaves the winner's object untouched.
The fix lands in the next commit.
* fix(engine): publish local storage writes with atomic visibility
Close the class, not the instance. The local adapter admitted three
ways for a reader to observe a write that was acknowledged or visible
before its bytes were complete:
1. write_text_if_absent acknowledged success when the buffered
tokio::fs::File write_all resolved -- i.e. when the bytes reached
tokio's internal buffer, not the file. A caller reading back its own
acknowledged write could see an empty object (the ~50% cluster
import flake under full-workspace load; the regression test failed
at iteration 0 with 0 of 8192 bytes visible).
2. The same call published its CLAIM (create_new) before its CONTENT,
so concurrent readers saw an empty claimed file in the window.
3. write_text (plain tokio::fs::write) exposed truncated content
mid-replace -- silently falsifying write_sidecar's 'readers either
see the complete sidecar or none' contract on local FS (true on S3,
where PutObject is atomic).
A flush in write_text_if_absent would have fixed only (1). Instead,
both local write paths now publish complete temp files atomically:
rename for replace (write_text -- the idiom write_text_if_match
already used) and hard_link for no-replace (write_text_if_absent --
link fails AlreadyExists, so exactly one of N concurrent claimants
wins and the winner's object is fully readable at the instant it
becomes visible). The local adapter now honors the same object-level
atomic-visibility contract as the S3 adapter, which is what every
caller (recovery sidecar protocol, cluster state CAS) was written
against. Crash-orphaned *.tmp.* files are inert: the sidecar sweep
filters to .json, and cluster state reads address state.json by name.
fsync/durability policy is unchanged (no fsync before, none now);
this fix is about visibility ordering, not power-loss durability.
Pre-existing on main (landed with the multi-graph server mode change,
PR #119); surfaced by this branch's heal work only because one extra
list_dir per write shifted test timing. Cluster lib suite: 12/25
failures before, 0/25 after. Turns the previous commit's red test
green.
* refactor(engine): one storage implementation over object_store for every backend
Collapse LocalStorageAdapter (hand-rolled tokio::fs) and
S3StorageAdapter into a single ObjectStorageAdapter backed by
Arc<dyn object_store::ObjectStore> -- LocalFileSystem for local URIs,
the existing AmazonS3 build for s3://, plus a pub in_memory()
constructor (full contract including TRUE conditional updates; the
in-memory test backend testing.md asked for at the adapter level).
Why: the acknowledged-before-visible bug showed the two-impl shape has
no referee -- one prose contract, two independent answers. Upstream
LocalFileSystem::put_opts is byte-for-byte the staged-temp+rename/
hard_link idiom that fix converged on, and Lance's own commit protocol
is built on the same primitives (put-if-not-exists / rename-if-not-
exists), so the substrate-aligned move is to stop hand-rolling it.
The per-backend residue shrinks to a UriCodec (URI <-> object path)
and one capability flag.
Semantics preserved by construction, with three deliberate deltas:
- exists() is now object-store-semantics everywhere (head + non-empty
prefix fallback): an EMPTY local directory no longer 'exists'. The
only dir-shaped caller (_graph_commits.lance probes) self-heals via
ensure_commit_graph_initialized where it previously wedged loudly.
- A directory at an object path reads as NotFound, not as an IO error
('only objects exist'). The cluster unreadable-payload test used a
same-named directory as a portable non-NotFound trigger; it now uses
chmod 000, which still models genuine transient IO.
- write_text_if_match keeps content-token semantics on local
(PutMode::Update is NotImplemented upstream for LocalFileSystem in
0.12.5 and 0.13.2); the capability flag gates the token SOURCE in
read_text_versioned too -- an ETag token with content-compare writes
would lose every CAS.
delete_prefix keeps a local remove_dir_all branch: directories are a
local-FS concept, and list+delete would leave empty skeletons that
cluster graph_root_exists (raw Path::exists) reports as still present.
LocalStorageAdapter remains as a delegating shim so the pinned
contract tests gate this swap textually unchanged; the shim and the
test parameterization over local + in-memory land next. Cargo gains
the explicit 'fs' feature (already transitively enabled by lance).
* test(engine): one executable storage contract, run against every backend
Remove the LocalStorageAdapter delegation shim and migrate its
construction sites to ObjectStorageAdapter::local(). Replace the
per-backend duplicated tests with a single contract_suite asserting
the trait's promises (atomic replace, exists incl. the dataset-root
prefix probe, one-winner if_absent, versioned CAS with loud CAS-lost,
rename, list round-trip with no sibling-prefix bleed, idempotent
delete/delete_prefix), run against the local backend and the new
in-memory backend -- which implements true conditional updates, so the
strong-CAS path is exercised without a bucket. The bucket-gated S3
variant already exists (s3_adapter_conditional_writes_contract).
New local-specific pins for the deliberate semantic edges of the
collapse: empty directories are not objects (exists=false; the Lance
dataset-root probe shape is the non-empty case), file://-anchored and
spaces-in-path list output round-trips byte-identically into
read_text, dot-segment paths are lexically absolutized (the CLI's
./graph.omni shape), and upstream rename creating missing destination
parents. The acknowledged-write visibility regression test stays, now
documenting that the cross-API std::fs read-back is the point.
* refactor(cluster): drop put_json's per-backend atomicity branch
The local temp+rename dance predates the storage adapter guaranteeing
atomic visibility; now that write_text publishes via a staged temp +
rename on the filesystem (and a single atomic PUT on object stores) by
contract, the branch duplicated upstream behavior. One call, both
backends.
* docs: storage adapter collapse — contract, in-memory backend, local CAS gap
- testing.md: the 'no MemStorage backend' note is half-closed —
ObjectStorageAdapter::in_memory() covers the text-object layer with
the full contract (true conditional updates); Lance datasets bypass
the adapter, so the engine substrate ask stays open.
- invariants.md: truth-matrix Tests row updated; new Known Gap for
local write_text_if_match (upstream PutMode::Update is unimplemented
for LocalFileSystem; content-token emulation is safe only under the
cluster lock protocol — close before admitting a lock-free caller).
- writes.md: backend notes for the unified adapter (name#N staging
residue invisible to the sweep, backend-wrapped error text with
exists()-probing for missing-vs-error, loud permission failures).
* docs: finish renaming the storage adapters in user docs and test comments
storage.md's URI-scheme table and the S3 failpoint test's doc comment
still named the deleted LocalStorageAdapter/S3StorageAdapter; both now
describe the unified ObjectStorageAdapter over object_store, including
the relative-path absolutization note for local URIs.
* test(engine): pin branch-awareness of the drift guard's recovery advice
A pending sidecar on ANOTHER branch does not cover this branch's
drift: with a deferred feature-branch sidecar on disk and genuinely
uncovered drift on main, the main write's error must still point at
omnigraph repair -- a read-write reopen recovers the sidecar but
cannot repair main's uncovered drift. Currently red: the guard
matches sidecar pins by table_key only, so the feature sidecar flips
main's advice to the reopen path. Fix in the next commit.
Surfaced by external review of the drift-guard change.
* fix(engine): branch-aware sidecar matching in the drift guard's advice
The commit-time drift guard's sidecar-covered check matched pins by
table_key alone, so a pending sidecar on another branch flipped this
branch's uncovered-drift advice from 'run omnigraph repair' to the
reopen path -- and a reopen recovers that sidecar but cannot repair
this branch's drift. Compare the pin's table_branch too. Turns the
previous commit's red test green.
Surfaced by external review of the drift-guard change.
* test(engine): pin heal non-interference with a live schema apply
The write-entry heal's schema-staging reconcile runs before any queue
acquisition, so a load on the same handle, overlapping a schema apply
parked between its staging write and manifest commit, promotes the
apply's staging files (new catalog live against the old manifest),
classifies the LIVE apply's sidecar, and publishes its registrations
out from under it. The resumed apply then collides with its own stolen
commit. Currently red with:
Lance("Concurrent modification: table version 3 already exists for
node:Tag")
The fix (per-sidecar reconcile under the sidecar's write-queue guards,
plus a serialization key the schema-apply writer and the heal both
acquire) lands in the next commit.
Surfaced by external review of the write-entry heal.
* fix(engine): serialize the heal's schema-staging reconcile with live schema applies
The write-entry heal ran recover_schema_state_files up front, before
acquiring any queue guards. Overlapping a live schema apply parked
between its staging write and manifest commit, the heal promoted the
apply's staging files (new catalog live against the old manifest),
classified the LIVE apply's sidecar, and published its registrations —
the resumed apply then collided with its own stolen commit.
Correct by construction:
- New schema-apply serialization queue key, acquired by the schema-
apply writer (alongside its per-table keys) from before write_sidecar
until after delete_sidecar. Per-table keys alone don't cover a
registration-only migration, which pins no existing tables but has a
sidecar and staging files on disk.
- The heal reconciles schema staging lazily, PER SchemaApply sidecar,
after acquiring that sidecar's guards (including the serialization
key) and re-confirming the sidecar exists — a sidecar that survives
the queue wait belongs to a dead writer, so the reconcile can no
longer race a live apply. Recomputing per sidecar also removes the
staleness of one up-front result across a multi-sidecar pass.
- Omnigraph::refresh drops its up-front reconcile-and-pass-through
(same race, and a pre-promoted result would make the heal's guarded
reconcile see clean staging and wrongly defer the sidecar): it now
reconciles standalone only when NO sidecar exists — which cannot
race a live apply, whose sidecar always precedes its staging files —
and otherwise defers entirely to the heal.
The open-time sweep keeps its precomputed reconcile: open has no
concurrent writers. Turns the previous commit's red test green.
Surfaced by external review of the write-entry heal.
Self-audit addendum folded in: refresh's no-sidecar gate had a TOCTOU
(a live apply could write its sidecar + staging between the empty
check and the reconcile) — the standalone reconcile now holds the
serialization key across the list-then-reconcile pair. The remaining
residual is cross-process only (in-process queues cannot serialize
against a writer in another process; the open-time sweep has the same
pre-existing exposure) and is now an explicit Known Gap in
invariants.md rather than an implicit one.
* test(engine): pin catalog reload after the heal recovers a schema apply
When the write-entry heal rolls a crashed apply's SchemaApply sidecar
forward on the same handle, disk and manifest move to the new schema
(staging promoted, registrations published) but the handle's in-memory
schema_source/catalog do not. Subsequent writes then validate against
the stale catalog and reject rows of types the graph already has.
Currently red with:
record 1: unknown node type 'Tag'
refresh() reloads after its heal; the write entry points must too.
Fix in the next commit.
Surfaced by external review of the write-entry heal.
* fix(engine): reload the in-memory catalog after the heal recovers a schema apply
heal_pending_recovery_sidecars refreshed the coordinator and
invalidated the runtime cache after processing sidecars, but never
reloaded schema_source/catalog — so a write whose entry heal rolled a
crashed SchemaApply sidecar forward proceeded to validate against the
OLD schema while disk and manifest were already on the new one.
reload_schema_if_source_changed is the same post-heal step refresh()
already runs; it no-ops on the (overwhelmingly common) non-schema heal
because the on-disk source is unchanged. Turns the previous commit's
red test green.
Surfaced by external review of the write-entry heal.
* test(engine): pin that a deleted-branch sidecar cannot wedge the graph
A rollback-eligible sidecar pinned to a branch is deferred by every
roll-forward-only pass; if the branch is then deleted, the sidecar
survives, referencing a branch with no manifest tree. The heal (every
write entry) and the open-time sweep (every ReadWrite open) both fail
opening the dead branch, and repair refuses while a sidecar is pending
-- a terminal read-only state with manual sidecar surgery as the only
exit. Currently red with:
Lance("Not found: .../__manifest/tree/feature/_versions")
The branch's tree and forks are already reclaimed, so the pinned drift
is unreachable and the sidecar is provably moot; the fix classifies it
as an orphaned-branch terminal state (audit + discard) in both passes.
Surfaced by review (P1, verified by repro).
* fix(engine): classify deleted-branch sidecars as orphaned instead of wedging
A deferred (rollback-eligible) sidecar pinned to a branch survives
branch_delete; both the write-entry heal and the open-time sweep then
failed unconditionally opening the dead branch -- every write and
every ReadWrite open errored, and repair refuses while a sidecar
pends. Terminal state, manual sidecar surgery the only exit.
The branch's tree and per-table forks are already reclaimed at delete,
so the drift the sidecar pins is unreachable and the sidecar is
provably moot. Both passes now check the sidecar's branch against the
manifest's branch list (the authority -- deliberately NOT inferred
from a Not-found on open, which could be a transient storage error
masking real recovery intent) and discard orphans with an
OrphanedBranchDiscarded audit row, commit appended on main since the
sidecar's own branch no longer has a commit graph.
The open-time half is pre-existing; the write-entry heal made it hot.
Turns the previous commit's red test green.
Surfaced by review (P1, verified by repro).
* chore: harden review nits — vacuous CI filter, root-runner skip, liveness note
- ci.yml: the RustFS sidecar-lifecycle step now fails loudly if the
's3_' name filter matches zero tests (cargo passes vacuously on an
empty filter; the step exists specifically to prove S3 sidecar I/O
coverage). The pre-existing CLI smoke step has the same shape and is
left for a follow-up.
- cluster unreadable-payload test: cfg(unix) + a skip-with-log when
running as root (mode 000 is still readable to root, common in
container dev runners), so the test degrades instead of failing.
- refresh: document the one-pass-late convergence for legacy staging
residue while non-SchemaApply sidecars pend, so nobody 'fixes' it by
re-running the reconcile unserialized — the exact race the
serialization key closes.
* test(engine): pin orphan-discard idempotency across a delete fault
discard_orphaned_branch_sidecar writes its audit row and main commit
before deleting the sidecar; a Phase D delete fault leaves the sidecar
on disk with the audit already durable, and the retry repeated the
whole path -- a second OrphanedBranchDiscarded audit row (and commit)
for the same operation. Currently red: 2 rows after one fault + retry.
The retry must only finish the delete. Fix next.
Also promotes the recovery-audit kinds reader into the shared test
helpers (it was recovery.rs-local).
Surfaced by external review of the orphan-discard fix.
* fix(engine): orphan-discard idempotency + heal reports acted-vs-deferred
Two review findings on the recovery surface:
- discard_orphaned_branch_sidecar now checks the audit table for an
existing (operation_id, OrphanedBranchDiscarded) row before appending
the commit + audit pair, so a Phase D delete fault retries ONLY the
delete instead of duplicating audit rows and commit-graph entries.
Cold path: the list scan runs only when an orphaned sidecar exists.
Turns the previous commit's red test green (exactly one audit row
across fault + retry).
- process_sidecar returns whether durable state changed; the heal sets
processed_any only for sidecars that were actually rolled forward /
rolled back / audit-recovered (orphan discards count). Deferred
sidecars (rollback-eligible, invariant-violating, unpromoted
SchemaApply) no longer trigger a per-write schema reload + full
runtime-cache invalidation while they pend -- the cache is
snapshot-keyed so this was waste, not corruption, but it was paid on
every write until reopen. Acted-paths' processed=true remains pinned
by load_after_schema_apply_phase_b_failure_uses_recovered_catalog
(the reload depends on it).
Surfaced by external review.
* test(engine): pin the orphan-discard audit-append fault leg as documented tolerance
The orphan discard's commit append and audit append are two writes; a
failure between them leaves a recovery commit with no audit row, and
the retry (keyed on the audit row, the operator-facing record) appends
a second commit before the audit lands. This is the same
not-atomic-pair-write tolerance record_audit documents and the
manifest->commit-graph Known Gap covers for every publish: bounded
commit-graph noise, audit row exactly-once under clean failures.
Keying idempotency on commit rows instead would need an operation_id
column on _graph_commits, and audit-before-commit would dangle the
graph_commit_id join -- both worse than the documented residual.
Make the tolerance explicit instead of implicit: docstring names the
window, a failpoint sits inside it, and the new test pins convergence
across the fault (sidecar consumed, exactly one audit row), completing
the orphan-discard fault matrix alongside the delete-fault leg.
Surfaced by external review of the orphan-discard idempotency.
* test(engine): pin honest drift-guard advice when sidecar listing fails
The guard's unwrap_or(false) conflated 'classified as uncovered' with
'could not classify': a transient list fault on the guard's second
list (the entry heal's first list having succeeded) confidently routed
the operator to omnigraph repair even when the heal had just deferred
a rollback-eligible sidecar -- and repair refuses while a sidecar is
pending. Currently red: the error says 'run omnigraph repair' with no
mention of the reopen path. The fix names both paths plus the failure
cause when classification is impossible.
Surfaced by external review of the drift-guard fallback.
* fix(engine): admit ambiguity in the drift guard when sidecar listing fails
Replace the unwrap_or(false) fallback with a tri-state: covered ->
reopen advice; uncovered -> repair advice; listing FAILED -> say the
drift could not be classified, name the cause, and give both paths in
order ('run repair, or reopen read-write if repair reports a pending
sidecar'). The old fallback confidently routed a transient list fault
to repair, which refuses while a sidecar is pending -- a self-
correcting but pointless detour. The conflict itself is still always
raised; only the advice degrades honestly. Turns the previous commit's
red test green.
Surfaced by external review of the drift-guard fallback.
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Markdown
# Architectural Invariants
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**Type:** standing review checklist
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**Status:** living document
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**Audience:** anyone proposing, reviewing, or implementing an OmniGraph change
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This file is intentionally short. It records the rules that should be in
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working memory for every non-trivial change. Detailed mechanics live in the
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area docs linked below.
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Use it this way:
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- Review the change against **Hard Invariants** and the **Deny-list**.
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- If code and docs disagree, either fix the code or add/update a **Known Gap**.
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- Keep implementation ledgers, roadmap detail, and historical MR notes in the
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per-area docs. This file is the filter, not the encyclopedia.
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## Hard Invariants
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1. **Respect the substrate.** Lance owns columnar storage, per-dataset
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versioning, fragments, branches, compaction, cleanup, and index primitives.
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DataFusion should own relational execution where it fits. Do not add custom
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|
WALs, transaction managers, buffer pools, page formats, or local clones of
|
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substrate behavior. Read [lance.md](lance.md) before guessing.
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2. **Graph visibility is manifest-atomic.** Lance commits are per dataset.
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OmniGraph's graph-level atomicity comes from publishing one manifest update
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for the whole graph, guarded by expected table versions and sidecar recovery.
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No write path may make a subset of touched node/edge tables visible as a
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graph commit.
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3. **A query reads one snapshot.** Query execution captures a manifest snapshot
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|
for its lifetime. Do not re-read branch head mid-query to discover newer
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table versions.
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4. **Mutations publish at one boundary.** A `mutate_as` or `load` operation
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accumulates constructive writes, commits each touched table at the end, then
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publishes one manifest update. Do not commit per statement. Delete-only
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|
queries are the documented inline residual; the parse-time D2 rule prevents
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mixing deletes with insert/update until Lance exposes two-phase delete.
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Read [writes.md](writes.md) and [execution.md](execution.md).
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5. **Recovery is part of the commit protocol.** Writers that can advance Lance
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HEAD before manifest publish must write `__recovery/{ulid}.json` sidecars.
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`Omnigraph::open` in read-write mode runs the all-or-nothing sweep; the
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write entry points (`load_as`, `mutate_as`, `apply_schema_as`,
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`branch_merge_as`) and `refresh` run roll-forward-only recovery in-process,
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|
so a long-lived process converges on its next write rather than at restart. Do not add a new writer kind without
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sidecar coverage or an explicit proof that no Lance HEAD can move before
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manifest publish.
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6. **Strong consistency is the default.** Reads are snapshot-isolated, writes
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|
are durable before acknowledgement, and branch reads observe the current
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|
committed graph state. Any eventual-consistency mode must be explicit,
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read-only, auditable, and non-default.
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7. **Indexes are derived state.** Reads must see the correct result for the
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branch they read even when index coverage is partial. Expensive index work
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|
should converge from manifest state instead of extending the critical write
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|
path. Scalar staged index builds and vector inline residuals are documented
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|
in [writes.md](writes.md) and [indexes.md](../user/indexes.md).
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8. **Schema identity survives renames.** Accepted schema identity must remain
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stable across type and property renames. Rename support belongs in migration
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planning, not in "drop and recreate" behavior. See the known gap below.
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9. **Schema/data integrity failures are loud.** Type errors, required-field
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|
misses, invalid edge endpoints, cardinality violations, and unsupported
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|
mixed mutation modes fail before a graph commit is published. The system must
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|
not invent placeholder nodes or silently weaken integrity.
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10. **Query semantics are first-class IR concepts.** Search modes, mutations,
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|
polymorphism, traversal, retrieval scores, imports, and policy predicates
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|
belong in typed AST/IR/planner structures. Do not smuggle semantics through
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strings, side tables, global state, or transport-specific flags.
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11. **Transport/auth stay at the boundary.** Kernel crates should not depend on
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HTTP, OpenAPI, bearer-token parsing, or future transport protocols. The
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server resolves bearer tokens to actors; clients cannot set actor identity
|
|
directly.
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|
|
12. **Bearer-token plaintext is not retained.** Server startup hashes bearer
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|
tokens, authentication uses constant-time comparison, and request handling
|
|
carries only the resolved actor identity and hash-derived match state.
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|
|
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13. **Operational failures are bounded and observable.** Timeout, memory, OOM,
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|
partial result, recovery, and conflict paths must fail loudly or degrade in
|
|
a documented way. If a metric affects plan choice or operator behavior, it
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|
must be exposed through the relevant trait or observability surface.
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|
|
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14. **Tests match the boundary being changed.** Prefer extending the existing
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|
test that owns the area. Planner changes need planner-level coverage,
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|
storage changes need storage/recovery coverage, and end-to-end tests are not
|
|
a substitute for missing lower-level assertions. Read [testing.md](testing.md)
|
|
before adding tests.
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|
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|
## Current Truth Matrix
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|
| Area | Current state | Source |
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|---|---|---|
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| Multi-table commit | Manifest CAS plus recovery sidecars; not a single Lance primitive | [writes.md](writes.md), [architecture.md](architecture.md) |
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|
| Constructive mutations | In-memory `MutationStaging`, one end-of-query table commit per touched table, then one manifest publish | [writes.md](writes.md), [execution.md](execution.md) |
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|
| Deletes | Inline-commit residual; delete-only queries allowed, mixed insert/update/delete rejected by D2 | [query-language.md](../user/query-language.md), [writes.md](writes.md) |
|
|
| Branch delete | Manifest is the single authority, flipped atomically first; per-table forks + commit-graph branch are derived state, reclaimed best-effort (`force_delete_branch`) with the `cleanup` reconciler as the guaranteed backstop. Reusing a name whose reclaim failed before `cleanup` surfaces an actionable error | [branches-commits.md](../user/branches-commits.md), [maintenance.md](../user/maintenance.md) |
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| Schema validation | Type checks, required fields, defaults, edge endpoint checks, and edge cardinality are enforced on write paths | [schema-language.md](../user/schema-language.md), [execution.md](execution.md) |
|
|
| Unique constraints | Intra-batch and write-path checks exist; intake and branch-merge derive the composite key through one shared function (`loader::composite_unique_key`, a separator-free `Vec<String>` tuple) and fail loudly on an un-keyable column type rather than silently exempting it; full cross-version uniqueness against already-committed rows is still a gap | [schema-language.md](../user/schema-language.md) |
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|
| Storage trait | `TableStorage` (via `db.storage()`) is staged-only; the inline-commit residuals (`delete_where`, `create_vector_index`) are split onto a separate sealed `InlineCommitResidual` trait reached via `db.storage_inline_residual()` (MR-854), so §1 holds by construction; capability/stat surfaces are roadmap | [writes.md](writes.md), [architecture.md](architecture.md) |
|
|
| Index lifecycle | `ensure_indices` is explicit today; reconciler-based convergence is roadmap | [indexes.md](../user/indexes.md), [maintenance.md](../user/maintenance.md) |
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|
| Traversal IDs | Runtime still builds `TypeIndex`; Lance stable row-id based graph IDs are roadmap | [architecture.md](architecture.md), [query-language.md](../user/query-language.md) |
|
|
| Auth | Bearer token hashing and server-side actor resolution are implemented at the HTTP boundary | [server.md](../user/server.md), [policy.md](../user/policy.md) |
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|
| Tests | Tempdir-backed Lance tests are the current substrate; the storage adapter has an in-memory backend for adapter-level contract tests, but Lance datasets bypass it | [testing.md](testing.md) |
|
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|
|
The branch-delete reconciler is authority-derived: it reclaims orphaned forks
|
|
today and degrades to a no-op if Lance ships an atomic multi-dataset branch
|
|
operation, so the design composes with that future rather than blocking it. This
|
|
is the same shape as invariant 7 (indexes are derived state); prefer it over a
|
|
recovery-sidecar-style approach for any new multi-dataset metadata operation,
|
|
since the sidecar would be scaffolding to remove once the substrate closes the gap.
|
|
|
|
## Known Gaps
|
|
|
|
Do not hide these behind invariant wording. Either move them forward or keep
|
|
them explicit.
|
|
|
|
- **Rename-stable schema identity:** the invariant is that accepted IDs survive
|
|
renames. The current compiler still derives type IDs from `kind:name`; this
|
|
must be fixed before relying on renamed IDs across accepted schemas.
|
|
- **Storage abstraction:** `TableStorage` is present, sealed, and canonical for
|
|
staged writes. MR-854 sealed it: `db.storage()` exposes only staged primitives
|
|
+ reads, and the inline-commit residuals are split onto a separate sealed
|
|
`InlineCommitResidual` trait reached via `db.storage_inline_residual()`, so a
|
|
new writer cannot couple a write with a HEAD advance through the default
|
|
surface. The dead legacy methods (`append_batch` on the trait,
|
|
`merge_insert_batch{,es}`, `create_{btree,inverted}_index`) were removed. The
|
|
remaining residuals are `delete_where` (gated on MR-A — Lance v7.x bump)
|
|
and `create_vector_index` (gated on Lance #6666); see
|
|
[lance.md](lance.md) and [writes.md](writes.md). New write paths should use
|
|
the staged shape unless a documented Lance blocker applies.
|
|
- **Deletes and vector indexes:** `delete_where` and vector index creation still
|
|
advance Lance HEAD inline because the required public Lance APIs are missing.
|
|
Keep D2 and recovery coverage in place until those residuals are removed.
|
|
- **Blob-column compaction:** Lance `compact_files` mis-decodes blob-v2 columns
|
|
under its forced `BlobHandling::AllBinary` read ("more fields in the schema
|
|
than provided column indices"), so `optimize` skips any table with a `Blob`
|
|
property — reporting `SkipReason::BlobColumnsUnsupportedByLance` (loud, not a
|
|
silent drop) behind the `LANCE_SUPPORTS_BLOB_COMPACTION` gate. Reads and writes
|
|
are unaffected; only space/fragment reclamation on blob tables is deferred.
|
|
Remove the skip when the upstream Lance fix lands — the
|
|
`lance_surface_guards.rs::compact_files_still_fails_on_blob_columns` guard
|
|
turns red on that bump to force it.
|
|
- **Recovery is serialized against live writers in-process only:** the
|
|
write-entry heal (and `refresh`) serialize against a live writer's sidecar
|
|
lifetime via the per-`(table, branch)` write queues plus the schema-apply
|
|
serialization key — all in-process primitives. A recovery pass in one
|
|
process cannot serialize against a live writer in another (the open-time
|
|
sweep has the same exposure, and always has): it may roll a live foreign
|
|
writer's sidecar forward, which degrades to publisher-CAS contention for
|
|
data writes but can race the schema-staging promotion for a foreign live
|
|
schema apply. Multi-process writers on one graph are already documented
|
|
one-winner-CAS territory; closing this fully needs a cross-process
|
|
serialization primitive (e.g. lease-based use of the schema-apply lock
|
|
branch) — design it before promoting multi-process write topologies.
|
|
- **Local `write_text_if_match` is not a cross-process CAS:** object-store
|
|
backends use a true conditional put (ETag If-Match; the in-memory test
|
|
backend too), but upstream `object_store` leaves `PutMode::Update`
|
|
unimplemented for `LocalFileSystem`, so the local path emulates CAS with
|
|
a content-token compare followed by an atomic replace — a check-then-act
|
|
gap plus content-token ABA. Every current caller goes through the cluster
|
|
lock protocol first, which makes this safe. A lock-free caller would get
|
|
S3-correct but local-racy behavior — the same divergence shape as the
|
|
acknowledged-before-visible bug this branch fixed. Close it (local CAS
|
|
primitive, or a trait-level lock requirement) before admitting any
|
|
lock-free `if_match` caller.
|
|
- **Manifest→commit-graph publish atomicity:** a graph commit advances
|
|
`__manifest` (the visibility authority) and then appends `_graph_commits` as
|
|
two separate writes (`commit_updates_with_actor_with_expected`, failpoint
|
|
`graph_publish.before_commit_append`). A crash between them leaves the manifest
|
|
at version N with no commit-graph row for N. Live reads and durability are
|
|
unaffected — the live version resolves via the manifest
|
|
(`GraphCoordinator::version()`), not the commit-graph head — and the open-time
|
|
recovery sweep does NOT repair it (`lance_head == manifest_pinned` classifies
|
|
`NoMovement`; a recovery sidecar would not change this). Impact is bounded to
|
|
commit history: `commit list` misses N, time-travel by commit id to N fails,
|
|
and merge-base loses a node (a likely-benign off-by-one re-merge). This affects
|
|
every publish, not a specific maintenance command. Eventual fix: make the
|
|
commit graph reconcilable from the manifest (or the two writes atomic) — not a
|
|
recovery-sidecar concern.
|
|
- **Planner capability/stat surfaces:** cost-aware planning, complete
|
|
capability advertisement, and explain-with-cost are roadmap. Do not describe
|
|
them as implemented.
|
|
- **Traversal execution:** current multi-hop execution still uses `TypeIndex`,
|
|
ad-hoc ID filtering, and eager materialization in places. Stable row IDs, SIP,
|
|
and factorization are target patterns, not current fact.
|
|
- **Retrieval ranks:** hybrid search works, but rank/score are not yet carried
|
|
everywhere as ordinary columns through the plan.
|
|
- **Policy pushdown and `Source`:** Cedar enforcement is at the HTTP boundary
|
|
today, and imports are still loader-shaped. Planner predicates and a unified
|
|
`Source` operator are roadmap.
|
|
- **Resource bounds:** some operations still lack enforced per-query memory or
|
|
time budgets. New long-running work should add explicit bounds rather than
|
|
widening the gap.
|
|
|
|
## Deny-list
|
|
|
|
If a proposal fits one of these, the burden is on the proposer to prove why the
|
|
case is exceptional.
|
|
|
|
- Custom WAL, transaction manager, buffer pool, page format, or storage engine.
|
|
- Per-table graph publishing outside the manifest publisher.
|
|
- Re-reading current branch head during a query instead of using the captured
|
|
snapshot.
|
|
- New write paths that can advance Lance HEAD before manifest publish without a
|
|
recovery sidecar.
|
|
- Cross-query `BEGIN`/`COMMIT` transactions in the OSS engine. Use branches and
|
|
merges for multi-query workflows.
|
|
- Acknowledging writes before durable Lance and manifest persistence.
|
|
- Silent fallback to eventual consistency, partial results, or dropped rows.
|
|
- State that drifts from Lance or the manifest when it can be derived.
|
|
- Job queues for manifest-derivable state where a reconciler is the right shape.
|
|
- Synchronous inline vector/FTS index rebuilds on the query commit path, except
|
|
for documented Lance API residuals.
|
|
- Side-channels for query semantics: hidden globals, magic strings, transport
|
|
flags, or out-of-band metadata.
|
|
- Cost-blind plan choice when statistics are available or required.
|
|
- Hidden statistics for behavior that affects planning or operator choice.
|
|
- Hash-map iteration order in result ordering, plan choice, or migration output.
|
|
- String-flattened SQL/filter generation when a structured pushdown API is
|
|
available.
|
|
- Eager multi-hop cross-product materialization when factorization fits.
|
|
- Ad-hoc `IN`-list filtering where SIP or another structured selectivity path
|
|
fits.
|
|
- Discarding retrieval score/rank before fusion or projection decisions.
|
|
- Auto-creating placeholder nodes for orphan edges.
|
|
- Raw filesystem I/O for cluster-stored state (ledger, lock, sidecars,
|
|
approvals, catalog) outside the cluster crate's storage module — every
|
|
stored byte goes through the engine `StorageAdapter` so `file://` and
|
|
`s3://` stay one code path.
|
|
- Wire-protocol-specific code in compiler or engine crates.
|
|
- Cloud-only correctness fixes or forks of the OSS engine for correctness.
|
|
- Mutating immutable substrate state in place, including Lance fragments or
|
|
index segments.
|
|
- Shipping observable behavior as if it were not part of the contract. Output
|
|
ordering, error text, timestamp precision, defaults, and latency profiles all
|
|
become dependencies once exposed.
|
|
|
|
## Review Checklist
|
|
|
|
Use this as yes/no/NA for any non-trivial design or PR:
|
|
|
|
- Does it respect Lance/DataFusion instead of rebuilding them?
|
|
- Does it preserve manifest-atomic graph visibility?
|
|
- Does every query keep one snapshot for its lifetime?
|
|
- Do mutations publish once at the commit boundary?
|
|
- Can every Lance-HEAD-before-manifest gap recover all-or-nothing?
|
|
- Are schema and edge integrity checks strict by default?
|
|
- Are query semantics represented in AST/IR/planner structures?
|
|
- Are transport, auth, and policy boundaries preserved?
|
|
- Are failures bounded, typed, and observable?
|
|
- Are result ordering and plan choices deterministic within a snapshot?
|
|
- Are stats/capabilities exposed when behavior depends on them?
|
|
- Are existing known gaps left no worse and documented if touched?
|
|
- Does the test live at the same boundary as the change?
|
|
- Does the change avoid every deny-list pattern, or justify the exception?
|
|
|
|
## Maintenance Policy
|
|
|
|
Update this file when an invariant changes, a known gap opens or closes, or a
|
|
new review anti-pattern deserves deny-list treatment. Prefer stable headings
|
|
over numbered sections so other docs can link here without churn.
|
|
|
|
Removing or relaxing a hard invariant requires the same review process as code.
|
|
Adding a known gap is acceptable when it makes reality explicit; leaving stale
|
|
claims is not.
|