v0.17.2

GoGraph v0.17.2 — see CHANGELOG.md for the per-release entry.

0.17.2 — 2026-10-13

10 commits — 8 non-merge commits and 2 merges — counted at 700eaed6, the tip of
release/0.17.2: the back-merge of v0.17.1 into develop (2b96446d); sprint 369, Bounded
rollback latency and memory for cut write statements (5 commits, merged at 18ec0dc7); the
release-preparation commit (b87ec901); and two stabilisation commits on the release branch, a
test-only fix to a gauge sampler (3b03915a, rmp #3126) and the constraint fix below
(700eaed6). 17 files changed, 1 262 insertions, 85 deletions
(git diff --shortstat v0.17.1..700eaed6).

This is a PATCH release: no exported API change, no WAL or on-disk format change. The only
non-test Go files changed are four files of package graph/lpg (lpg.go,
mvcc_abort_reclaim.go, mvcc_abort_release.go, mvcc_abort_sides.go) and four of package
cypher (api.go, exectx.go, undo_record.go, exec/constraints.go). Every declaration they
add or change is unexported: in graph/lpg, abortWithdrawsCreation, tombstoneAbortedBatch,
idBatchBitmap, countSideStores, and the lifeWithdrawal field sizeHint with its methods
tombstone and revive; in cypher, the Engine test seams beginTxGatesHookForTest and
delPropProbedHookForTest, the releasesOwed fields of Result and ExplicitTx,
Result.applyOwedReleases, and the signature of recordDelNodeProperty. No file under store/
changed. go.mod and go.sum are unchanged from v0.17.1.

Fixed

• A write statement cut by its context deadline no longer takes many times its deadline to
  roll back, nor multiplies its peak heap while doing so (rmp #3122, #3123, b1e9e21f).
  Present in v0.17.1 and earlier. The rollback deleted every node the statement had created
  through the ordinary delete path, which copied the whole copy-on-write tombstone bitmap once per
  node and recorded bookkeeping the abort then withdrew: the rollback was quadratic. A
  MATCH (a), (b), (c) CREATE () over 600 nodes cut at 1 s returned 8.6 to 9.2 s after its deadline
  and peaked at about 1.7 GB of heap; cut at 5 s it returned 64 s late and peaked at 7.2 GB. The
  abort now withdraws the nodes the statement created and flips their tombstones in batches, with
  the same end state. The same statement now returns about 1.4 s after a 1 s deadline with a peak
  of about 0.75 GB, and about 7.1 s after a 5 s deadline with a peak of about 3 GB. The rollback is
  now linear, at about 1 µs per created node. The deadline itself was always noticed within
  microseconds.
• A REMOVE racing a peer's rolled-back removal can no longer commit a node without a
  property its NOT NULL constraint requires (rmp #3127, 700eaed6). Present in v0.17.1 and
  earlier. The removal decided whether to check the node at commit from a probe of the present
  state; when that probe read a peer's uncommitted removal that the peer then rolled back, the
  removal still deleted the committed value but skipped the commit-time check. The check now
  follows the removal's effect. A second, narrower window is closed in the same commit: an
  explicit transaction whose BeginTx straddled a constraint registration between its catalogue
  reads skipped both the commit-time NOT NULL check and the straddler validation; BeginTx now
  reads the constraint generation first.
• Readers can no longer briefly see two holders of a UNIQUE value (rmp #3128,
  700eaed6). Present in v0.17.1 and earlier. A transaction that freed a UNIQUE value
  released it at its commit decision, before it was visible, so a peer could take the value and
  publish first; a snapshot between the two publications held the value twice. The release is now
  applied after publication, on the autocommit and the explicit-transaction path. Behaviour
  change: a concurrent write of a just-freed UNIQUE value, inside the window between the
  freeing transaction's commit decision and its visibility, is now refused with a constraint
  violation; a retry succeeds.
  The concurrency test that exposes both defects, TestConstraintDDLvsDML_NoViolationAdmitted,
  failed 9 runs in 200 on v0.17.1 and 3 in 100 at 3b03915a; after the fix it passed 1 000 of
  1 000 runs, and 200 of 200 under -race.

Performance

• The abort path allocates about a third less per created node (rmp #3125, 2885d7d3):
  pre-sized withdrawal lists, one bitmap Or/AndNot per batch of at least 1024 ids instead of
  per-id updates, and no duplicate unborn-mark pass. Rolling back a 5 s cut CREATE allocates
  197 B per id instead of 307. A large DELETE rollback was measured linear and is unchanged
  (rmp #3124).

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Further reading

• Narrative release notes: release-notes/v0.17.2.md
• Measured benchmark report: docs/benchmarks/v0.17.2.md
• Changelog file at this tag: CHANGELOG.md
• Commits in this release: https://github.com/FlavioCFOliveira/GoGraph/commits/v0.17.2

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Reproducibility: built from commit 3d5fd8c with Go 1.26.