v26.45.0 release notes

[bosconi]

The v26.45.0 release-note train, one commit per snapshot. Dates in RC snapshots are provisional until the release ships; the final snapshot sets the real dates.

rc.1 adds the ## v26.45.0 section — 7 Improvements, 1 Agent Skills entry, 7 Bug Fixes (15 published entries from 16 PRs) — and the v26.45 row in the self-managed operator compatibility table. No Features section: nothing in this snapshot's 229 in-scope PRs rises to one. The closest candidate is sum/avg over interval, which fills the last gap in the aggregate surface for a core type rather than adding a capability worth its own heading.

rc.2 adds 1 Bug Fix from 1 PR in scope — zero-downtime cut-overs stalling for hours when the incoming environmentd re-consolidated its whole catalog snapshot before every fence attempt and so lost the race against the serving instance's advancing frontier (#39482). Nothing omitted, nothing Borderline.

rc.3 adds 1 Improvement and amends another, from 2 PRs in scope. New: quieter logins with identity-provider group sync (#39434). Amended in place: rc.1's subject-alternative-name bullet now carries the exact-match pinned-CA carve-out (#39459) and cites both PRs — see the reviewer check below for why that is a replacement rather than a second bullet. Nothing omitted, nothing Borderline.

Provisional dates: Cloud 2026-10-08, Self-Managed 2026-10-09 — the first Thursday strictly after the v26.45.0-rc.1 tag's commit date (2026-10-02T02:23:01Z, a Friday), plus one day. Anchored on rc.1, so rc.2 and rc.3 introduce no drift and neither touches the compatibility YAML. Expect the final snapshot to move these one day earlier: both of the last two trains shipped on the Wednesday before the estimate (v26.43.0 on 2026-09-23 against 2026-09-24; v26.44.0 on 2026-09-30 against 2026-10-01). The estimate is kept as the rule specifies rather than pre-corrected.

⚠️ Reviewer checks

• rc.3 rewrites an rc.1 bullet rather than adding one, and that is deliberate. #39459 repairs a regression #39415 introduced earlier in this same unreleased train, so no released version ever showed the failure and a standalone "fixed" bullet would be false for every reader upgrading from v26.44.0. What it changes for that reader is the scope of rc.1's caveat: a schema registry server certificate byte-for-byte identical to its configured SSL CERTIFICATE AUTHORITY needs no reissue. The narrower alternative, if a reviewer prefers one bullet per snapshot: revert to rc.1's wording and accept a published caveat broader than the shipped behaviour — the safe-direction error, but still wrong.
• rc.3's group-sync entry is published over the rollout-lever default rule, and the LaunchDarkly evidence is weaker than the precedent it leans on. oidc_group_role_sync_enabled reads false at the tag (src/adapter-types/src/dyncfgs.rs:203-208) and is in KNOWN_CROSS_ENV_DIVERGENCES, not KNOWN_MISSING_FROM_LD — so an LD flag exists and its served value knowingly differs by environment, which is consistent with a per-customer opt-in but is not proof the feature is on. It is published on four grounds: the flag is environment-scoped, v26.40.0 rc.1 already published a fix on this same gated path (#38410), the capability was announced GA one release earlier, and the PR ships the new behaviour in the published sync-idp-groups.md docs page in the same diff. Confirm with the release owner; if it comes back negative, that is the entry to cut — the certificate entry is unaffected.
• Two entries are breaking-ish and need an upgrade-time action, and the notes schema has no "Breaking changes" heading. The stricter Kubernetes API server certificate verification (#39316) and the schema registry / COPY FROM subject-alternative-name requirement (#39415 + #39459) both sit in Improvements, phrased around the action a user must take. A reviewer may want them moved or called out more loudly. Related and omitted: #39351 moves all S3/AWS traffic onto rustls and webpki — if the same SAN strictness applies to a custom S3 endpoint in a Self-Managed deployment, it belongs in the same note; the PR does not say either way.
• Two zero-downtime cut-over fixes are published separately, by design. rc.1's #39151 (previous-generation replicas left running) and rc.2's #39482 (lost fence race against a large catalog audit log) are distinct failures with distinct mechanisms, so they are not merged. If a reviewer prefers one combined "zero-downtime cut-over reliability" bullet, that is an editorial call to make at final. Also deliberately unpublished on catalog: skip consolidation on syncs that apply no updates #39482: it is a regression since v26.22.0 by the author's own statement, and the fix does not cover syncs that do apply updates (DDL issued during takeover still consolidates the full snapshot) — the PR gives no measurement of that residual, so it is not claimed.
• Curated metric sinks are withheld for the fourth consecutive train (v26.39.0, v26.40.0, v26.42.0, v26.43.0). Three real fixes are Borderline behind enable_metric_sink, which reads false at this tag. Confirm with the release owner: if the flag is on in v26.45.0, publish #39332 (clearest candidate — it also removes the unattributable series from the metric's label set), #38910, and #39337. #39337 deserves a second look even if metric sinks stay off — the coordinator panic it fixes is reachable by any superuser via ALTER SYSTEM SET disabled_metric_sinks = '', a plain system variable with no feature-flag check.
• The schema-registry TLS fix is rc.1's closest call on the include side. #39362's only observed failures are in CI (test/kafka-auth, SS-115) — no customer report, no database-issues reference. It is published because the defect is in shipped code on a shipped path (librdkafka leaves a stale OpenSSL error on the tokio worker's error queue). If a reviewer wants only customer-observed fixes published, this is the entry to cut.
• The introspection-logging latency numbers were measured on one noisy shared machine. #39179's own caveat is not in the published entry, and #39178 adds metrics to confirm the effect elsewhere. A reviewer who wants the figures hedged should say "about 9–14 ms" or cut the halved-SELECT clause, which is the softer of the two claims.
• The materialized-view correction-buffer stack is omitted for want of an end-to-end number. #38894 / #38895 / #38896 are on the default-on path (enable_compute_correction_v2 is true) with real figures — 3503 ms → 1897 ms, 1.6x–2.0x — but every one is a bench of the buffer's own insert path, not of materialized-view ingest. If the compute team can supply a hydration or lag number, publish these as one Improvement; the per-clause provenance is already drafted in the review notes.
• The documented local kind install fails today, and the fix is a docs change. #39149 is omitted as documentation (the rubric excludes the class), but following the guide on v26.42.0 crash-loops environmentd with the exact Invalid Parquet file. Corrupt footer defect that #39115 fixes and this release publishes. Same call as #39125 in v26.44.0 rc.1. If a reviewer restores it, it is a Bug Fix.
• This branch will need a rebase if the v26.44.0 or v26.43.0 docs PRs merge first. _index.md here jumps from ## v26.45.0 straight to ## v26.43.0 — the v26.44.0 section is absent because that train's PR (#39138) has not merged, and the same holds for the v26.44 row in the operator-compatibility YAML. Whichever PR merges second needs the rebase to get the sections and rows into version order.
• Two PRs are excluded as already published by an earlier train — #39300 (published in v26.44.1 as "Lower balancerd memory use per connection") and #39130 (the materialize half of the materialize-docs → mz-docs rename, whose user-visible half shipped in v26.44.0). Accounted for in omitted.md under "Already published in an earlier release".

Inclusion rate: rc.1 is 7.0% (16/229), inside the usual 5–15% band; rc.2 is 1/1 and rc.3 is 2/2, which is the expected shape for a late RC — the set is cherry-picks a release manager has already filtered down. rc.1's denominator is dominated by automation: 125 of the 225 materialize PRs are dependency bumps, 65 of them a single Dependabot fan-out of the materialize-terraform-self-managed modules from 13.10.0 to 13.12.1 across five test/terraform directories — #39282 groups future Terraform releases into one PR so it does not recur. Strip the dependency bumps and rc.1's materialize side is 15 included out of 100 (15%). A further 22 PRs are CI/test-harness repair and 14 are documentation.

The agent-skills windows for rc.2 (2026-10-02T02:23:01Z, 2026-10-02T22:33:36Z] and rc.3 (2026-10-02T22:33:36Z, 2026-10-02T23:08:27Z] are both empty, re-checked against a widened query; MaterializeInc/agent-skills#88 merged 83 minutes after rc.3's upper bound and falls to the final snapshot.

Snapshot drafts (with PR links) in mz-skills:

• rc.1: release_notes.md / omitted.md
• rc.2: release_notes.md / omitted.md
• rc.3: release_notes.md / omitted.md

Borderline PRs omitted: rc.1: 12 — review borderline calls, rc.2: 0 — none, rc.3: 0 — none