PostgreSQL corruption fixes and QEMU block, AI policy, Realm work

PostgreSQL hackers closed in on several corruption and crash fixes while debating a stable-branch revert and a partition-attach slowdown. QEMU developers shipped a data-loss series for the preallocate filter, advanced Arm Realm confidential VM support, and revised AI contribution policy.

PostgreSQL index corruption after SET TABLESPACE rollback

PostgreSQL hackers converged on a fix for index corruption that follows rollback of ALTER TABLE SET TABLESPACE inside a transaction. The issue is tracked as BUG #19686 and was examined across 25 messages by seven participants. Operators who move tablespaces under transactional control need the correction to avoid silent index damage.

QEMU preallocate filter data-loss races

A 13-patch series on qemu-devel fixes data loss in the preallocate filter stemming from races between multi-AioContext writes and preallocation state. Two participants drove the technical discussion. The change matters for anyone depending on QEMU block-layer preallocation for consistent virtual disk contents.

Missing tts_tid causing ctid corruption

A patch restores the missing tts_tid in ExecForceStoreHeapTuple, which previously produced ctid corruption, unwanted table extension, and invalid pages after FOR UPDATE following GiST KNN scans. Five participants reviewed the problem on pgsql-hackers. Workloads that combine nearest-neighbor index scans with row locking are directly exposed.

QEMU AI contribution policy revision

QEMU published version 4 of a policy series that relaxes a blanket ban on AI-generated contributions, introducing attestation trailers and pre-approval for large submissions. Seven participants discussed the docs and AGENTS.md updates. The shift indicates how the project intends to handle generative-tool output going forward.

Partition attach cost linear in pg_constraint size

ATTACH PARTITION in PostgreSQL 18 slows linearly because CloneFkReferenced performs a sequential scan of pg_constraint, a cost that grew after not-null constraints were stored there. A patch proposes an index on confrelid. Sites with large constraint catalogs will see attach times climb without the index.

Arm Realm support for QEMU confidential VMs

An RFC version 5 series of 22 patches adds Arm RME Realm support so QEMU and KVM can run confidential virtual machines. The work was posted by a single author. It expands hardware-backed isolation options for Arm-based QEMU deployments.

Revert of RI fast-path batching from REL_19_STABLE

A proposal calls for removing RI fast-path batching from the REL_19_STABLE branch because of trigger and subtransaction interaction risks, while leaving the feature in master. Five participants examined the trade-off. Early adopters and packagers of version 19 must watch whether the optimization survives the stable cut.

Apply worker crash on deferrable primary keys

A patch eliminates an assertion crash in the logical-replication apply worker when the subscriber table carries only a deferrable primary key and lacks REPLICA IDENTITY FULL. Five participants confirmed the failure mode. Replication configurations that rely on deferrable constraints on the subscriber side need the fix to keep apply workers running.