Zombie PostgreSQL replicas: the WAL segment removed deadlock
PostgreSQL replicas on Kubernetes can get stuck in a WAL segment removed loop that passes liveness checks, and three fixes stop it for good.
Tag: postgresql
Why pg_dump backups on a PostgreSQL replica fail intermittently
Running pg_dump on a PostgreSQL replica can fail with conflict with recovery errors because the backup is a long read transaction colliding with WAL replay.
Postgres conflict with recovery: why replicas cancel queries
A PostgreSQL replica cancels long queries with conflict with recovery errors during VACUUM replication, and hot_standby_feedback fixes it without downtime.
A Local, Multi-Tenant Graph RAG System with LightRAG
How a local Ollama and LightRAG stack turns Graph RAG into a cheap, multi-tenant retrieval layer that only sends precise context to cloud models.
Fixing the Asia/Rangoon Postgres Error on Alpine Linux
If you recently updated your Docker images and were greeted by a PG::InvalidParameterValue: ERROR: time zone "Asia/Rangoon" not recognized, you aren't alone.
Zero-Downtime GKE Upgrades with PostgreSQL in the Cluster
A blue/green node pool runbook for upgrading GKE clusters with PostgreSQL running as a StatefulSet, without a maintenance window.
Zero-downtime GKE upgrades with PostgreSQL failover
Blue/green node pools plus a Kubegres replica promotion let you upgrade a GKE cluster, PostgreSQL included, without a maintenance window.
PostgreSQL on Ubuntu: install, user setup, and auth debugging
Install PostgreSQL from the PGDG repo on Ubuntu, set up a matching development role, and debug the password authentication failures Rails hits most.
PostgreSQL MD5 to SCRAM-SHA-256: a zero-downtime migration
PostgreSQL 18 deprecates MD5 authentication, and migrating to SCRAM-SHA-256 in mixed mode lets you switch pg_hba.conf without downtime or forced app changes.
PostgreSQL 18: What's New and How to Upgrade
PostgreSQL 18 adds better query parallelism, parallel logical replication apply, and more flexible partitioning, plus the pg_upgrade and dump/restore paths to get there.
Designing a Schema for an Optional Attribute
A one-line feature request, recording why a student failed a course, walks through three schema options: a nullable column, a normalized table, and jsonb.
Troubleshooting pgpool Connection Termination in Kubernetes
Intermittent pgpool connection drops in Kubernetes usually trace to max_connections, idle timeouts, or NetworkPolicy issues, found layer by layer.
PostgreSQL JSONB vs Linking Tables for Relationships
Comparing PostgreSQL jsonb columns against a traditional linking table for modeling course prerequisites, and where a hybrid of both makes more sense.
MySQL vs PostgreSQL: Foreign Key Deadlock Contention
How foreign key checks cause deadlock contention in MySQL InnoDB versus PostgreSQL, and why PostgreSQL's FOR KEY SHARE lock reduces the risk considerably.
Deadlocks in MySQL and PostgreSQL: Foreign Keys vs Performance
How deadlocks form in MySQL and PostgreSQL under concurrent updates, and the trade-off between foreign key integrity and write throughput.
Kubernetes Node Upgrades: Cordon, Drain, and Failover
A cordon-drain-upgrade runbook for Kubernetes nodes, plus the PodDisruptionBudgets, priority classes, and lifecycle hooks that prevent outages.
Building and Deploying pgpool Images with GitHub Actions
A GitHub Actions workflow that builds multi-architecture pgpool images for several versions in parallel and pushes them to GitHub Container Registry.
Materialized Views: Speeding Up Queries with a Tradeoff
Materialized views cache expensive PostgreSQL queries as physical tables, trading storage and refresh cost for fast reads, plus how pgpool fits in.
PostgreSQL Sequence Conflicts After an Upgrade: How to Fix Them
Upgrading PostgreSQL can leave sequences out of sync with table max values, causing duplicate-key errors and blocked sign-ins, fixed here with SQL and bash.
Zero-Downtime PostgreSQL Upgrades With Logical Replication
A bash script that sets up PostgreSQL logical replication, publications, and subscriptions to perform a major-version upgrade without downtime.
Rails N+1 Queries: joins vs preload vs eager_load vs includes
What joins, preload, eager_load, and includes actually do in ActiveRecord, shown with real SQL logs, plus the chained calls that quietly bring the N+1 back.
Postgres 'Too Many Connections': Debugging Pgpool-II Limits
Debugging a Postgres 'too many connections' error through Pgpool-II's num_init_children and max_pool settings, and the fix that stopped clients queueing.
Scaling PostgreSQL on Kubernetes with Kubegres
How Kubegres brings primary/standby failover, automatic backups, and PITR to a self-hosted PostgreSQL cluster on Kubernetes without a managed database bill.
Pgpool-II: Middleware for PostgreSQL
Pgpool-II sits between PostgreSQL and its clients as a connection pooler and load balancer, and this covers the Kubernetes setup that keeps writes consistent.
Database Auditing: pg_audit vs audited vs paper_trail
A comparison of database auditing options, pg_audit, audited, paper_trail, Hibernate Envers, and SQL Server temporal tables, and when each one fits.