https://walstack.io/insightsWalStack provides evidence-first PostgreSQL performance investigations for SaaS engineering teams, with specialist capability across SQL Server, pgvector, Snowflake and OLAP workloads.enhttps://walstack.io/insights/postgresql-foreign-key-index-slow-deletehttps://walstack.io/insights/postgresql-foreign-key-index-slow-deleteKiran SabneTested on PostgreSQL 18: deleting one customer took 1.7 seconds and ran 22 sequential scans because two foreign keys had no index. Find them, and why pg_stat_statements hides the cost.Wed, 04 Nov 2026 00:00:00 GMThttps://walstack.io/insights/postgresql-18-async-io-io-methodhttps://walstack.io/insights/postgresql-18-async-io-io-methodKiran SabneLab-tested on PostgreSQL 18.6: sync, worker and io_uring on cold sequential and bitmap heap scans.Tue, 27 Oct 2026 00:00:00 GMThttps://walstack.io/insights/rds-aurora-postgresql-14-extended-support-costhttps://walstack.io/insights/rds-aurora-postgresql-14-extended-support-costKiran SabneDates, per-vCPU billing on primaries, standbys and replicas, and how to list affected instances.Tue, 27 Oct 2026 00:00:00 GMThttps://walstack.io/insights/pgvector-087-cve-upgradehttps://walstack.io/insights/pgvector-087-cve-upgradeKiran SabneCVE-2026-103484 in IVFFlat index builds: version checks, privileges and a tested extension upgrade.Tue, 27 Oct 2026 00:00:00 GMThttps://walstack.io/insights/snowflake-gen2-vs-adaptive-warehouseshttps://walstack.io/insights/snowflake-gen2-vs-adaptive-warehousesKiran SabneACCOUNT_USAGE checks for idle credits, spills, pruning and queuing before converting a warehouse.Tue, 27 Oct 2026 00:00:00 GMThttps://walstack.io/insights/postgresql-autovacuum-not-removing-dead-tupleshttps://walstack.io/insights/postgresql-autovacuum-not-removing-dead-tuplesKiran SabneTested on PostgreSQL 18: autovacuum ran 4 times and removed no dead tuples while one session sat idle in transaction. Find the blocker and reclaim the space.Thu, 22 Oct 2026 00:00:00 GMThttps://walstack.io/insights/postgresql-transaction-id-wraparoundhttps://walstack.io/insights/postgresql-transaction-id-wraparoundKiran SabneReproduced on PostgreSQL 18: the wraparound warning, the error that stops writes, why VACUUM FREEZE did not help, and the recovery steps that worked.Thu, 22 Oct 2026 00:00:00 GMThttps://walstack.io/insights/postgresql-work-mem-temp-file-spillshttps://walstack.io/insights/postgresql-work-mem-temp-file-spillsKiran SabneTested on PostgreSQL 18: 336 MB of temp file spills at the default work_mem. Raising it 64x removed every spill but saved at most 8%. What to change instead.Thu, 22 Oct 2026 00:00:00 GMThttps://walstack.io/insights/how-to-profile-slow-postgresql-querieshttps://walstack.io/insights/how-to-profile-slow-postgresql-queriesKiran SabneRank with pg_stat_statements, capture real plans with auto_explain, reproduce with EXPLAIN ANALYZE, then validate the fix.Wed, 21 Oct 2026 00:00:00 GMThttps://walstack.io/insights/pg-upgrade-check-failureshttps://walstack.io/insights/pg-upgrade-check-failuresKiran SabneReal pg_upgrade --check output from a tested PG14 to PG18 run: checksum mismatch, prepared transactions, reg* columns, and what --check misses.Wed, 21 Oct 2026 00:00:00 GMThttps://walstack.io/insights/postgresql-upgrade-logical-replication-slotshttps://walstack.io/insights/postgresql-upgrade-logical-replication-slotsKiran SabneTested PG14 to PG18: pg_upgrade --check passed with a Debezium slot present, and the slot was gone afterwards.Wed, 21 Oct 2026 00:00:00 GMThttps://walstack.io/insights/rds-aurora-postgresql-14-to-18-blue-greenhttps://walstack.io/insights/rds-aurora-postgresql-14-to-18-blue-greenKiran SabneIn-place upgrade or Blue/Green: where the downtime goes and the logical replication limits that break Blue/Green.Wed, 21 Oct 2026 00:00:00 GMThttps://walstack.io/insights/postgresql-slow-queries-pg-stat-statementshttps://walstack.io/insights/postgresql-slow-queries-pg-stat-statementsKiran SabneRank statements by total time, diff snapshots and read buffer and temp-file signals. Lab-tested on PostgreSQL 17.Wed, 14 Oct 2026 00:00:00 GMThttps://walstack.io/insights/postgresql-slow-after-major-upgradehttps://walstack.io/insights/postgresql-slow-after-major-upgradeKiran SabneA tested pg_upgrade lost optimizer statistics; how to detect and fix it on self-managed PostgreSQL and RDS.Wed, 14 Oct 2026 00:00:00 GMThttps://walstack.io/insights/pgvector-filtered-search-missing-resultshttps://walstack.io/insights/pgvector-filtered-search-missing-resultsKiran SabneMeasured iterative scans, exact search and partial indexes for filtered HNSW queries.Wed, 14 Oct 2026 00:00:00 GMThttps://walstack.io/insights/sql-server-parameter-sniffing-query-storehttps://walstack.io/insights/sql-server-parameter-sniffing-query-storeKiran SabneQuery Store diagnosis and measured PSP, RECOMPILE and covering-index fixes on SQL Server 2022.Wed, 14 Oct 2026 00:00:00 GMThttps://walstack.io/insights/postgresql-14-minor-version-deadlineshttps://walstack.io/insights/postgresql-14-minor-version-deadlinesKiran SabneCheck minor-version deadlines that arrive before the PostgreSQL 14 major-version date.Tue, 13 Oct 2026 00:00:00 GMThttps://walstack.io/insights/what-ai-misses-postgresqlhttps://walstack.io/insights/what-ai-misses-postgresqlKiran SabneA safe production recommendation needs workload, waits, change history and validation.Tue, 13 Oct 2026 00:00:00 GMThttps://walstack.io/insights/pgvector-hnsw-vs-ivfflathttps://walstack.io/insights/pgvector-hnsw-vs-ivfflatKiran SabneMeasure recall, filtered result count, latency and operational cost on the real workload.Tue, 13 Oct 2026 00:00:00 GMThttps://walstack.io/postgresql-concurrency-and-locking-a-comprehensive-guidehttps://walstack.io/postgresql-concurrency-and-locking-a-comprehensive-guideKiran SabneFind blockers, long transactions and DDL queues before changing queries.Tue, 13 Oct 2026 00:00:00 GMThttps://walstack.io/how-to-scale-postgresql-databases-with-partitioninghttps://walstack.io/how-to-scale-postgresql-databases-with-partitioningKiran SabneVerify partition pruning, data lifecycle and constraint trade-offs.Tue, 13 Oct 2026 00:00:00 GMThttps://walstack.io/mastering-clustering-in-postgresql-for-enhanced-query-performancehttps://walstack.io/mastering-clustering-in-postgresql-for-enhanced-query-performanceKiran SabneTest physical row order benefits against rewrite and locking costs.Tue, 13 Oct 2026 00:00:00 GMThttps://walstack.io/sharding-postgresql-techniques-for-horizontal-scalabilityhttps://walstack.io/sharding-postgresql-techniques-for-horizontal-scalabilityKiran SabneAssess shard keys, routing, rebalancing and cross-shard work.Tue, 13 Oct 2026 00:00:00 GMThttps://walstack.io/postgresql-indexing-when-brin-beats-b-treehttps://walstack.io/postgresql-indexing-when-brin-beats-b-treeKiran SabneDecide from correlation, query evidence and index trade-offs.Tue, 13 Oct 2026 00:00:00 GMThttps://walstack.io/building-a-semantic-similarity-search-api-with-fastapi-sentence-bert-and-postgresql-pgvectorhttps://walstack.io/building-a-semantic-similarity-search-api-with-fastapi-sentence-bert-and-postgresql-pgvectorKiran SabneMove from a pgvector demo to measurable recall, filtering and latency.Tue, 13 Oct 2026 00:00:00 GMThttps://walstack.io/mastering-mongodb-locking-concurrency-and-performance-optimization-a-deep-divehttps://walstack.io/mastering-mongodb-locking-concurrency-and-performance-optimization-a-deep-diveKiran SabneWiredTiger lock modes, versioning and contention diagnosis, with corrections.Tue, 13 Oct 2026 00:00:00 GMT