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.
Find the queries dragging your Postgres down, read their plans, and fix them in order of impact.
Read the guide →Which indexes to add, which to drop, and how to spot redundant index debt before it costs you writes.
Read the guide →How autovacuum works, when it falls behind, and how to keep bloat from eating your storage and your buffer cache.
Read the guide →Sizing pools, PgBouncer modes, and how to stop idle-in-transaction sessions from exhausting max_connections.
Read the guide →Track lag, WAL throughput, and replication slots before they turn into stale reads or a full disk.
Read the guide →
Backups, restores, PITR, archive gaps, and recovery drills for PostgreSQL.
AWS RDS, Azure Database for PostgreSQL, Google Cloud SQL, AlloyDB, and managed PostgreSQL monitoring notes.
Connection storms, pool saturation, PgBouncer behavior, and max_connections pressure.
CPU, memory, disk, temp files, checkpoints, buffers, and workload pressure.
Index design, index debt, reindexing, constraint indexes, and evidence-driven DDL.
Lock waits, deadlocks, blocking chains, idle transactions, and transaction hygiene.
Galera clustering, InnoDB and Aria internals, replication, optimizer behavior, and MariaDB operations notes.
InnoDB internals, replication, locking, query performance, and MySQL operations notes.
HNSW, IVFFlat, recall, embedding search, and production RAG performance notes.
Replica lag, WAL growth, failover readiness, hot standby behavior, and replication slots.
Query plans, EXPLAIN ANALYZE, planner regressions, pagination, joins, and statistics.
Wait statistics, tempdb, Query Store, Always On availability groups, and SQL Server operations notes.
Autovacuum, dead tuples, bloat, wraparound, MVCC, freeze age, and visibility.
The storage team kept reporting a write burst every sixty seconds, and the database kept getting blamed for being badly written. It was the classic checkpoint doing exactly what recovery interval told it to do. How checkpoints actually schedule, and…
Error 824 at 03:12 on a Sunday: a torn page in the order history table, 40,000 orders unreadable, and a restore that would cost six hours of data. What CHECKDB actually checks, how to run it on a busy box,…
The same ALTER TABLE ADD COLUMN finished in 120 milliseconds on staging and ran for nearly four hours in production. The difference was not the table, the data, or the hardware — it was the MariaDB version and its instant-DDL…
One tenant held 60% of a 480-million-row events table and the optimizer kept planning for a world that did not exist. MariaDB's engine-independent histograms fixed it — here is how they are stored, collected, and when they lie.
Every ninety seconds the whole Galera cluster froze for two to four seconds, and the slow query log was empty. wsrep_flow_control_paused was climbing because one node applied writesets slower than the cluster delivered them. Here is the full diagnosis.
CPU at eleven percent, disks idle, and 1,200 connections timing out: the instance had burned through every worker thread and the queue was growing by the second. What worker threads actually are, what eats them, and why raising the ceiling…
The subscriber was forty-five minutes behind and the on-call message said replication was broken. Replication was not broken — one DELETE of two million rows was replaying as two million singleton statements through a single-threaded agent. How to read the…
The maintenance plan said ONLINE = ON, so the rebuild was supposed to be invisible. Instead it queued behind a nine-minute report, blocked every query on the orders table, and the Saturday morning checkout went down. How online rebuilds actually…
I once watched a Profiler trace against a production instance take the box from 2,000 batches a second to timeout errors in ninety seconds. Extended Events is the replacement, but only if you write sessions with the same discipline Profiler…
Every morning at 8:15 the buffer cache hit ratio sagged, page life expectancy fell off a cliff, and someone asked if the server needed more RAM. The server needed an index. How to read buffer pool counters without the folklore,…