[ibrahim halatci (ihalatci)]

DESCRIPTION: Update PostgreSQL 19 CI and regression coverage to RC1

Update build, nightly cassert, and pg_upgrade image pins to the published PostgreSQL 19 RC1 release images from merged citusdata/the-process#253 (image suffix -va0a5582). The stable image publication succeeded for merge commit a0a5582b39e72cec476f7b6ba37a2cf97572b930 in the-process build-test-images run. Preserve the existing exclusion of PG19 from Citus upgrade coverage.

Add a distributed ON CONFLICT regression for PostgreSQL's fix to inference when an index expression on a NOT NULL column simplifies to a Var (upstream commit). No Citus source change was indicated: the regression fails on PostgreSQL 19 Beta 4 and passes on RC1.

RC1 feature audit

The audited upstream range is REL_19_BETA4 (b73d13c32c834a2c8e1c60cb92f79530376cedf1) through REL_19_RC1 (0b8bff042a997fe50fcd1c4c83b9ef1cc9ed8a89): 132 commits and 300 changed paths, with no feature-revert commit.

The Citus umbrella features remain present in RC1:

• REPACK / REPACK CONCURRENTLY: PG19: reject distributed REPACK CONCURRENTLY before exclusive lock wait #8756 / PG19: use ShareUpdateExclusiveLock for REPACK CONCURRENTLY #8805 remain relevant.
• EXPLAIN IO: PG19: propagate the EXPLAIN IO option to worker nodes #8770 / PG19: propagate EXPLAIN IO to worker nodes #8807 remain relevant.
• Constraint enforceability: PG19: report explicit unsupported ALTER CONSTRAINT errors #8758 / Report unsupported ALTER CONSTRAINT explicitly #8808 remain relevant.
• JSON COPY: merged PG19: route distributed JSON COPY TO through coordinator formatting #8760 / Fix PG19 relation JSON COPY TO routing #8765 remains compatible with RC1.
• Distributed REPACK CONCURRENTLY support: Support distributed REPACK CONCURRENTLY #8772 remains a design-only exception without an implementation PR.

The approved dependent topology is:

• native stack #8929 -> #8805 -> #8807;
• Report unsupported ALTER CONSTRAINT explicitly #8808 as an independent sibling based directly on this branch after removing unrelated DETACH changes.

Version-neutral #8759 and #8762 are no longer subissues of #8782.

PostgreSQL RC2 is scheduled for 2026-11-12 and GA for 2026-11-19. RC2 must be rechecked for the open upstream eager-aggregation and CHECK-enforcement items before final PG19 feature completion.

Validation

Local validation on PostgreSQL 19 RC1: pg19 (7/7), multi_upsert (7/7), multi_insert_select_conflict (7/7), multi_copy (15/15), multi_outer_join (7/7), multi_deparse_shard_query (7/7), multi_deparse_function (7/7), and multi_join_order_additional (16/16, with base schedule and whole schedule line). merge also passed on Beta 4 after installing the missing postgres_fdw test dependency.

The repartition planning/pruning/task-assignment debug task-ID output differences reproduce on both Beta 4 and RC1; no expected output was changed for them.

The prior Citus head 7259ac9c94e9a6595eac092b18afc47b69197d4a passed all automatic checks. This suffix-only update switches CI to the successfully published stable RC1 images; checks for the current head will run after this update.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.81%. Comparing base (bcf4bfd) to head (edfc2db).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8929      +/-   ##
==========================================
+ Coverage   88.79%   88.81%   +0.01%     
==========================================
  Files         290      290              
  Lines       65455    65455              
  Branches     8255     8255              
==========================================
+ Hits        58124    58135      +11     
+ Misses       4947     4937      -10     
+ Partials     2384     2383       -1     

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[Colm (colm-mchugh)]

Lgtm, good to merge once CI is all green.

[Colm (colm-mchugh)]

Lgtm, good to merge once CI is all green.