Database Technology

Henrietta Dombrovskaya has released significant updates to the pg_acm extension, addressing bugs she identified after leaving DRW. The update includes several requested new functions and conceptual improvements to the tool's core logic. While the code is now published, the author notes that comprehensive documentation is still pending.

• pg_acm receives critical bug fixes and new function additions.
• Conceptual changes improve the extension's underlying logic.
• Documentation is currently incomplete despite code release.
• Updates stem from post-DRW development backlog.

This AWS blog post details a three-tier architecture combining Amazon ElastiCache for Valkey, an exact-match cache, and Amazon Aurora PostgreSQL to perform membership lookups. By layering a Bloom filter with strict verification against the relational source of truth, the pattern eliminates false-positive risks inherent in probabilistic structures. The design achieves sub-millisecond decision times at peak throughput while ensuring data correctness.

• Use Valkey for high-speed probabilistic filtering before hitting Aurora PostgreSQL
• Always verify Bloom filter hits against an exact-match layer to prevent false positives
• Architect for sub-millisecond latency without compromising data integrity guarantees
• Leverage this pattern for high-throughput membership queries in read-heavy workloads

Fleet impact: For Aurora PostgreSQL and ElastiCache fleets, this pattern offers a robust way to offload high-volume membership checks while maintaining strict consistency. Ensure your Valkey instances are sized for the filter load and that the exact-match fallback path remains performant under peak concurrency.

A PostgreSQL agent using the MCP protocol can inadvertently read another tenant’s data when connecting through PgBouncer in transaction mode. This occurs because the pooled connection retains session state from a previous client, bypassing the expected isolation. The issue highlights a critical flaw in relying on session variables for multi-tenant isolation when using connection pooling.

• PgBouncer transaction mode reuses connections without resetting session state
• MCP protocol lacks inherent session isolation for agent tool calls
• RLS policies reading session vars are vulnerable to connection reuse
• Agents may access unauthorized tenant data via pooled connections
• Reset session state explicitly before each transaction or tool call

PostgreSQL 19 will miss its expected fall release window due to a heavy review cycle and significant feature reversions during beta. The development team is prioritizing quality over the original timeline, reducing the release scope to stabilize the codebase. Beta 4 is scheduled for September 24, 2026, with the final release pushed back by weeks or potentially months.

• Postgres 19 is delayed beyond the traditional fall release schedule.
• Major features reverted during beta to maintain code quality.
• Release scope is being reduced to meet stability requirements.
• Beta 4 is set for September 24, 2026, with final release pending.
• Expect weeks to months of delay before the official launch.

The PostgreSQL 19 stable branch saw 71 commits in its final week, but this was offset by 74 reverts across six separate pull requests. The most significant revert involves the online data checksum transition feature, which was pulled by Daniel Gustafsson on September 16. This reflects a conservative stabilization approach as the release window closed.

• PostgreSQL 19 stabilized with a net positive of 71 commits after reverting 74 changes.
• Online data checksum transition was removed from v19, likely due to stability concerns.
• Six features remain tracked for inclusion, with two still actively shipping.
• PostgreSQL 20 master branch received 46 commits in the same reporting window.