Citus removed the node. Its cleanup records stayed behind.
Draining a Citus worker and removing it straight away left cleanup records for a node that no longer existed. A later rebalance retried one move 33 times.
11 min read
Topic
PostgreSQL
Replication, point-in-time recovery, promotion, connection limits, and the version-upgrade surprises that only ever show up under production traffic.
PostgreSQL is the database I have used longest — since 2017 — and still my default for transactional systems. Most of what I know about it comes from the operational side rather than the query side: how far behind a standby actually falls under write pressure, point-in-time recovery you have rehearsed instead of documented, promotion while traffic is still arriving, connection limits meeting an application that opens a pool per worker, and major-version upgrades. On my failover rig, PostgreSQL 18 streaming replication held a replay lag of 383 µs — measured on the rig, not quoted from a release note.
8 posts
All writingFiltered vector search returned four rows instead of ten, and nothing failed
A 10% filter cut pgvector's post-filtered answer to 3.9 of 10 rows and OpenSearch's filtered recall to 0.745 on 381,559 vectors. No error was raised.
12 min read
pgBackRest against a Patroni cluster: archive, rebuild, and restore
Wire pgBackRest into a running Patroni cluster over mutual TLS with Ansible, then prove it: full backup, replica rebuilt from the repo, and a point-in-time restore.
~90 min on an existing cluster; the restore drill itself is ~15 min
Patroni HA on PostgreSQL 18 with etcd, proven by killing the primary
Build a two-node Patroni cluster on Rocky 8 under QEMU, then SIGKILL the leader and measure the promotion, the timeline bump, and the pg_rewind rejoin.
~2–3 h first bring-up (TCG is slow); ~5 min for the failover itself
Dedicated pgBackRest TLS on RHEL 8 with Ansible—before Postgres
Stand up a dedicated pgBackRest TLS repo host on generic/rhel8 with Ansible-issued certs, then prove server-ping and mTLS from a client VM.
~90 min first bring-up (TCG + dnf)
amd64 Vagrant labs on Apple Silicon without broken host networking
Apple Silicon labs that boot still fail host and mesh ping when you use aarch64 boxes or park the VMs on your Wi‑Fi subnet.
~60–90 min first bring-up (TCG is slow)
PostgreSQL 18 won't take a volume at /var/lib/postgresql/data
The mount point moved in the PG 18 image, so every compose file copied from a 12–17 guide breaks. The corrected file, then replication, promotion and PITR.
~35 min hands-on
A failover lab: six database engines, eight scenarios, every one run
Six database engines, eight failover scenarios, one 8-CPU Docker rig. The results matrix, the headline measurements, and how to run the first scenario.
~45 min hands-on