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Database Technology

Saturday, September 26, 2026 · 7 stories, curated & summarized — click any story for the source.

Perplexity has shifted its search infrastructure from Amazon DynamoDB to CobbleDB, a custom key-value store written in Rust. This migration was designed to handle large document batches more efficiently, resulting in a fivefold reduction in query latency. The move also lowered cloud storage costs while maintaining high throughput for production traffic.

  • CobbleDB is a homegrown Rust key-value store replacing DynamoDB for search workloads.
  • Query latency dropped by 5x after migrating away from managed DynamoDB.
  • Cloud storage expenses were reduced through more efficient data handling.
  • The architecture supports high query volumes with improved efficiency.

Christophe Pettus explains how the new GUC max_slot_wal_keep_size mitigates the risk of replication slots silently consuming all available disk space on a primary server. By enforcing a hard limit on WAL retention for stalled replicas, this parameter allows the system to terminate stuck connections rather than crashing due to out-of-memory or disk-full errors. This change shifts the failure mode from a catastrophic hardware constraint to a controlled service interruption.

  • Prevents primary disk exhaustion caused by unbounded WAL accumulation from stalled replicas.
  • Automatically terminates replication slots that exceed the specified WAL size threshold.
  • Replaces potential OOM or disk-full crashes with a controlled connection drop.
  • Essential for protecting high-throughput clusters with unreliable network links.

AWS demonstrates a fully managed, event-driven CDC pipeline that streams row-level changes from RDS or Aurora PostgreSQL to Amazon S3 in near real time. The solution is deployed via a single CloudFormation template and operates within private subnets, eliminating the need for an internet gateway or public exposure. This approach enables secure, serverless ingestion of database changes for downstream analytics or archival.

  • Deployable via single CloudFormation template for rapid infrastructure-as-code setup
  • Runs in private subnets without internet gateway, enhancing security posture
  • Supports both RDS for PostgreSQL and Aurora PostgreSQL sources
  • Enables near real-time row-level change capture to Amazon S3
  • Serverless execution via AWS Fargate removes operational overhead
AWS What's New awsdatabase ↺ since 09-25

AWS RDS PostgreSQL 19 Beta 4 adds refined autovacuum and query performance

Amazon RDS for PostgreSQL now offers Beta 4 of version 19 in the Database Preview Environment. This release refines query performance and autovacuum management capabilities introduced in earlier betas. Key updates include bug fixes for the pg_stat_autovacuum_scores view and corrected freeze-score scaling to improve tuning accuracy.

  • Test PostgreSQL 19 Beta 4 in the RDS Database Preview Environment to evaluate pre-release features.
  • Autovacuum now shares a rebalanced cost limit across parallel workers to respect configured maintenance limits.
  • pg_stat_autovacuum_scores view now correctly reports metrics for TOAST tables.
  • Freeze-score scaling has been corrected, allowing more effective autovacuum prioritization for large tables.
CHECKLISTKey PostgreSQL 19 Beta 4 UpdatesTest in RDS Database Preview EnvironmentAutovacuum shares rebalanced cost limitFix pg_stat_autovacuum_scores viewCorrect freeze-score scaling
PostgreSQL News database ↺ since 09-24

PgBouncer 1.26.0 patches three CVEs and adds Meson build support

PgBouncer 1.26.0 addresses three critical vulnerabilities affecting unauthenticated clients, including a SCRAM nonce crash, an integer overflow causing infinite loops, and unbounded login work from malicious servers. The release introduces new configuration options like pool_idle_timeout and per-user query_wait_timeout, while dropping the deprecated online restart flag. It also adds Meson build support and begins tracking search_path and default_transaction_read_only by default.

  • Update immediately to patch DoS vectors in SCRAM auth and packet buffer logic.
  • Leverage new pool_idle_timeout for better resource management.
  • Use per-user/database query_wait_timeout for granular control.
  • Migrate to Meson build system; remove usage of -R online restart flag.
  • Verify search_path and read-only transaction behavior changes in your fleet.
CHECKLISTPgBouncer 1.26 Hardening StepsUpdate immediately to patch DoS vectorsLeverage new pool_idle_timeout settingUse per-user query_wait_timeoutMigrate to Meson build systemVerify search_path behavior changes
PostgreSQL Releases databasereleases ↺ since 09-23

PostgreSQL 19 Beta 4 released

The PostgreSQL global development group has published the fourth beta release for version 19. This pre-release iteration continues the stabilization process ahead of the final 19.0 launch, incorporating community feedback and bug fixes from earlier beta cycles. Engineers can now evaluate upcoming features and performance improvements in a test environment.

  • Test upcoming PostgreSQL 19 features in non-production environments.
  • Monitor for regression bugs introduced in this fourth beta cycle.
  • Review release notes for new capabilities and deprecated functions.
  • Plan upgrade timelines based on the final 19.0 release schedule.
HOW IT WORKSPostgreSQL 19 Beta 4 Path1Evaluate beta features2Monitor for regressions3Review release notes4Plan upgrade timeline
AWS What's New awsdatabase ↺ since 09-25

Amazon RDS for PostgreSQL adds post-quantum TLS key exchange

Amazon RDS for PostgreSQL now supports post-quantum TLS key exchange for encrypting data in transit. This feature is available for RDS for PostgreSQL versions 18 and higher. Users can modify the ssl_groups parameter to select cryptographic groups from an allow list. This allows alignment with organizational security standards.

  • Available for RDS for PostgreSQL v18+ via ssl_groups parameter
  • Enables post-quantum cryptography for data in transit
  • Select groups from RDS allow list to match security policies
  • Simplifies setup for compliant PostgreSQL deployments
CHECKLISTEnable Post-Quantum TLSUpgrade to RDS for PostgreSQL v18 or higherModify the ssl_groups parameter on your instanceSelect groups from the RDS allow listAlign choices with organizational security standards
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