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 reporting subscriber was twenty-six hours behind, but the publisher swore replication was fine — and it was, because it was happily streaming WAL nobody could apply. One duplicate key had killed the apply worker on Tuesday, and the only…
A column vanished from the billing_events table on a Friday afternoon, git blamed the wrong person, and by the time we looked, the logs with the real session had rotated away. The fix was an audit trail built on event…
The bloat alarm on orders fired while an autovacuum worker had been "running" for five hours — pg_stat_activity showed it waiting on BufferPin, a wait that appears in no lock view and answers to no timeout. The blocker was an…
A cleanup query with NOT IN deleted nothing for six months because one NULL made every row 'unknown'. Then a migration flipped where NULLs sort, and a dedupe job started keeping the wrong record. NULL semantics are SQL-standard until the…
We doubled the RAM, set innodb_buffer_pool_size=96G in my.cnf, restarted — and got 24G. Eight months earlier an on-call engineer had run SET PERSIST during an OOM scare, and mysqld-auto.cnf had been silently overriding the option file ever since.
After our 5.7-to-8.0 upgrade the error log ballooned from 40MB to 1.8GB a day, so we installed log_filter_dragnet — and our first broad rule quietly deleted the startup banners that would have been the timeline of a later crash investigation.…
We flipped innodb_flush_log_at_trx_commit to 2 and commit p99 dropped from 11ms to 0.8ms — a beautiful graph. Eleven weeks later a kernel panic proved what that graph cost: 47 orders the app had confirmed and InnoDB had not.
One Group Replication member came back from a 40-minute network partition with 61,000 transactions queued — and writes on the two healthy members crawled for nine minutes while it caught up. The quota math, the thresholds that matter, and what…
A compliance-mandated password rotation took the app down for 11 minutes at 02:20 — half the pods had the new credential, half had the old one, and the retry storms did the rest. MySQL 8.0.14's dual passwords make that outage…
Today's vendor news for database operators: Aurora DSQL gets per-statement CloudWatch Database Insights, ARC Region switch learns to orchestrate RDS read-replica switchovers, AWS walks through multilingual FTS migration to PostgreSQL, AlloyDB's ScaNN index hits 10 billion vectors, and Timestream for…