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DBMS Weekly — 2026-05-31 (week of 2026-05-25–2026-05-31)

PostgreSQL

  • 5 PostgreSQL locking behaviours that trip people up — counterintuitive production-outage locks from a PostgreSQL engineer: FIFO lock-queue chained blocking behind a waiting ACCESS EXCLUSIVE, invisible FK FOR KEY SHARE deadlocks, unique-check INSERT deadlocks, the wraparound-prevention autovacuum that refuses to be cancelled, and VACUUM's hidden truncate-phase ACCESS EXCLUSIVE (and how it force-cancels standby SELECTs via max_standby_streaming_delay). (Shinya Kato · dev.to)
  • How soon is now()? A frozen-timestamp retry-loop bug — a real distributed-locking bug: now() returns the transaction start time, so a retry loop sharing one transaction re-evaluated last_updated < now() - timeout against a constant and never made progress; fix is clock_timestamp(), with the testing-seam lesson on why unit + e2e both missed it. (Oskar Dudycz · event-driven.io)
  • TOAST: where PostgreSQL hides big values — reproducible walkthrough of the over-2KB out-of-line storage path: compression strategies, the per-column STORAGE knob, why a wide text/jsonb column silently changes your I/O profile, and how to see TOAST traffic. (Radim Marek · boringsql.com)
  • Why Postgres lacks transparent data encryption — why TDE never landed in core (the buffer/WAL/temp-file surface area, key management, and the recurring pg_tde-style extension route requiring a patched server), and what at-rest encryption actually buys you versus filesystem/volume encryption. (pgEdge)

Community pulse

  • SQLite is all you need for durable workflows — the week's biggest DB thread: a long argument over building durable-execution engines directly on an embedded DB instead of a dedicated workflow system, trading off single-node simplicity against scale. (Hacker News · 720 pts, 387 comments)
  • Building durable workflows on Postgres — the Postgres-flavoured half of the same debate (DBOS): can the database be your only durable-execution substrate, and where do queues/outboxes still beat it. (Hacker News · 359 pts, 147 comments)
  • CQL: Categorical Databases — category-theory-based data integration and schema mapping resurfaced and drew a genuinely technical thread on whether the formalism pays its way in practice. (Hacker News · 111 pts, 39 comments)
  • SQLite does not accept agentic code — Simon Willison on SQLite's stance against AI-generated contributions, prompting a wider argument about provenance, testing rigour, and the project's famously high bar. (Simon Willison · Hacker News)

Wider DBMS & distributed data

International (non-English sources)

  • Becoming postgres in someone else's cloud: a security crash-test of managed databases — a Yandex Cloud reliability lead documents two privilege-escalation vectors in managed PostgreSQL where the server runs code as superuser and bypasses the control-plane's restricted roles; both were found at two public cloud providers and fixed upstream and by the vendors before publication. (Evgeny Efimkin · Yandex Cloud / habr.com) [ru] (orig: «Как стать postgres в чужом облаке: краш-тест безопасности управляемых БД»)
  • Why Postgres with an external OLAP engine isn't really HTAP — argues that bolting an external columnar engine onto Postgres (separate storage model, ETL/CDC, parquet hand-off) breaks the single-transaction-visibility property real HTAP needs, and sketches doing OLTP + analytics over shared storage inside Postgres instead. (Tantor Labs · habr.com) [ru] (orig: «Почему PostgreSQL с внешним OLAP — это не совсем HTAP?»)
  • Polymorphic associations in PostgreSQL: helping the planner avoid performance cliffs — how the ORM-generated discriminated-FK pattern (type, id LEFT JOINed to every subtype) regresses, and three pgsql-hackers patches discussed in 2024–2026 that each target a different source of the regression in the optimizer. (Andrei Lepikhov · Tantor / habr.com) [ru] (orig: «Полиморфные ссылки в PostgreSQL: помогаем СУБД избежать провалов производительности»)

Upcoming events

  • Swiss PGDay 2026 — Rapperswil, CH, Jun 25–26 — the Swiss PostgreSQL conference, two tracks (EN/DE). Internals picks:
    • Deep dive into the PostgreSQL Front/Backend protocol (Xavier Fischer, EDB) — the wire protocol every pooler, proxy, and distributed router must speak.
    • Optimizer Hints in PostgreSQL (Michael Banck, credativ) — timely against PG19's new pg_plan_advice.
    • Zooming in on OOM: Postgres & Linux memory (Oleksii Kliukin & Dimitris Sideris, Tiger Data) — backend/OOM-killer interaction and memory accounting.

14 items · sources scanned: ~30 · community threads scanned: HN (postgres/database/sqlite/clickhouse queries, date-ranged) · international: ru (Habr) · filtered out as marketing/ads: ~10