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.
A booking platform stored start and end columns in MySQL, and its overlap queries were slow and quietly wrong at boundaries. Here is how tstzrange, GiST, and exclusion constraints fixed both, and what stays manual on MySQL.
When a bad migration forced a real point-in-time recovery, our restore took nine and a half hours against a two-hour RTO — replaying 1.8 TB of WAL is single-threaded, and we had never once timed it. The drill routine, the…
At 03:12 the primary vanished mid-query and the log only said "terminated by signal 9: Killed" — no ERROR, no WARNING, nothing. The kernel had picked our biggest backend. The memory accounting that explains why, the overcommit fix, and the…
A firmware-updated RAID controller spent a month writing occasional garbage pages into our events table, and we found out from a customer report, not from the database — because checksums were off. The initdb flag, the offline enable, the hidden…
Covering indexes can avoid table reads, but row visibility still matters. Compare InnoDB clustered-record checks with PostgreSQL visibility-map and VACUUM behavior.
One MySQL upsert statement burned 40,000 auto-increment IDs a second on the update path and deadlocked 180 times an hour under batch load. Here is what ON DUPLICATE KEY UPDATE actually does, what PostgreSQL ON CONFLICT does instead, and how…
Deleting one tenant row took forty-five minutes because a foreign key trigger was sequentially scanning a 90-million-row events table — inside the deleting transaction, while the lock queue grew behind it. The detection query, the rollback-safe EXPLAIN trick, and the…
pg_cron serializes runs of each job. Diagnose queued executions, coordinate duplicate callers, and monitor failures, duration, and missing successful runs.
Our 13-to-16 cutover with pg_upgrade --link took six minutes of actual upgrade and four hours of hangover: no planner statistics, one missing extension, and a standby rsync that silently synced nothing. The rehearsal routine and fallback plan that made the…
A failed three-statement MySQL migration left my schema half-applied at 2 a.m. with no way back. Here is why PostgreSQL's transactional DDL prevents exactly that, and how migration tooling treats the two engines differently.