4 min read
When Replication Slots Eat the Disk: A Diagnostic Walkthrough
If your Postgres disk is growing and you cannot identify the culprit, replication slots are usually the answer. Here is the diagnostic sequence.
Database Field Notes
Notes for the problems that show up after launch: bad plans, awkward migrations, index debt, vacuum pressure, replica lag, and the small decisions that keep PostgreSQL, MySQL, MariaDB, and SQL Server easier to operate.
Featured Guides
Slow query optimization
Find the queries dragging your Postgres down, read their plans, and fix them in order of impact.
Read the guide →Index optimization
Which indexes to add, which to drop, and how to spot redundant index debt before it costs you writes.
Read the guide →Vacuum guide
How autovacuum works, when it falls behind, and how to keep bloat from eating your storage and your buffer cache.
Read the guide →Connection pooling
Sizing pools, PgBouncer modes, and how to stop idle-in-transaction sessions from exhausting max_connections.
Read the guide →Replication monitoring
Track lag, WAL throughput, and replication slots before they turn into stale reads or a full disk.
Read the guide →Browse by Topic
Backups and Durability
9 articlesBackups, restores, PITR, archive gaps, and recovery drills for PostgreSQL.
Cloud Providers
5 articlesAWS RDS, Azure Database for PostgreSQL, Google Cloud SQL, AlloyDB, and managed PostgreSQL monitoring notes.
Connections and Pooling
10 articlesConnection storms, pool saturation, PgBouncer behavior, and max_connections pressure.
CPU, Memory, and I/O
17 articlesCPU, memory, disk, temp files, checkpoints, buffers, and workload pressure.
Indexes
37 articlesIndex design, index debt, reindexing, constraint indexes, and evidence-driven DDL.
Locks and Transactions
22 articlesLock waits, deadlocks, blocking chains, idle transactions, and transaction hygiene.
MariaDB
56 articlesGalera clustering, InnoDB and Aria internals, replication, optimizer behavior, and MariaDB operations notes.
MySQL
107 articlesInnoDB internals, replication, locking, query performance, and MySQL operations notes.
pgvector and RAG
15 articlesHNSW, IVFFlat, recall, embedding search, and production RAG performance notes.
Replication and WAL
28 articlesReplica lag, WAL growth, failover readiness, hot standby behavior, and replication slots.
Slow Queries
38 articlesQuery plans, EXPLAIN ANALYZE, planner regressions, pagination, joins, and statistics.
SQL Server
47 articlesWait statistics, tempdb, Query Store, Always On availability groups, and SQL Server operations notes.
Vacuum and Bloat
16 articlesAutovacuum, dead tuples, bloat, wraparound, MVCC, freeze age, and visibility.
Latest Field Notes
6 min read
Postgres Roles and Least Privilege: The Setup That Survives Audits
Most production databases run application traffic as a superuser. This is convenient and wrong. Here is the role hierarchy that takes a few hours to set up and saves you in the worst case.
5 min read
PostgreSQL Replication Monitoring: Lag, Slots, and Failover
Replication monitoring is not one lag number. You need to know stale-read risk, slot retention, replay delay, WAL growth, and whether failover would help or hurt.
6 min read
Row-Level Security in Postgres: Strong Defense, Costs You Will Encounter
RLS pushes access control into the database. It is more secure than application-side filters and slightly slower than no filter at all. Here is the framework for using it well.
5 min read
Postgres SSL Connections: Doing It Properly Without Losing a Day
SSL on Postgres is a one-line config change to enable and a multi-day project to do correctly. The default settings are not good enough.
5 min read
Auditing Sensitive Access in Postgres: Patterns That Survive Real Audits
"Did anyone read the customer table outside expected hours" is a common audit question. The answer is harder to produce than it should be unless you set up auditing deliberately.
5 min read
Connection Strings, Passwords, and Secrets: How to Stop Leaking Postgres Credentials
Most Postgres connection strings live in places they should not. Environment variables, config files, scripts, screenshots in Slack. Here is the discipline.
6 min read
AWS RDS Parameter Groups: The Postgres Settings That Actually Matter
RDS exposes hundreds of Postgres parameters through Parameter Groups. About a dozen of them are worth tuning. Here are the ones I always change and why.
5 min read
AWS Aurora Postgres Replica Lag: Different from Vanilla, Different to Diagnose
Aurora's replica lag has different mechanics than vanilla streaming replication. The dashboard metric "replica lag" can be misleading. Here is what it actually measures.
7 min read
PostgreSQL Locks and Deadlocks: Detection, Prevention, and Triage
Lock incidents feel mysterious because the database looks idle while requests wait. The fix starts with blockers, waiters, transaction age, and code paths that take locks in different orders.