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.
FTWRL waits for every in-flight statement, then makes everything else wait for it. MySQL 8.0's LOCK INSTANCE FOR BACKUP and performance_schema.log_status give backup tools a lighter path — and you a shorter outage.
When an AUTO_INCREMENT column hits its type's ceiling, every insert on that table fails at once. Field notes on the incident shape, a fleet-wide detection query, signed vs unsigned headroom, and migrating to BIGINT without downtime.
A crash mid-ALTER on 5.7 left orphaned #sql tables and dictionary mismatches you fixed with file surgery. MySQL 8.0's transactional data dictionary ended that era — and quietly retired a few other habits.
The adaptive hash index is a real CPU win on uniform point-lookup workloads and a latch nightmare on skewed ones. Here is how to tell which one you have, and what to do about it.
MySQL 5.7 has been end-of-life since October 2023, and plenty of production fleets still run it. Field notes on the upgrade checker, the removals that actually break apps, and a rollback plan that is honest about being a restore plan.
Logical backups scale badly by default. Field notes on where mysqldump stops working, what mydumper and myloader change, and the honest boundary where physical backups win.
An eighteen-second JSON_EXTRACT scan dropped to single-digit milliseconds with one generated column and one index. VIRTUAL vs PERSISTENT, the real indexing rules, and the replica determinism caveats nobody mentions.
One SET GLOBAL gives MariaDB per-account, per-client, per-table, and per-index counters — enough to answer 'who is hammering this table' in a single query. Here is what userstat collects, what it costs, and where the unused-index caveats hide.
MariaDB ships a real thread pool in the community server — MySQL charges extra for one. Here is how pool-of-threads works, when it saves you under a connection storm, and when it quietly serializes you.
MariaDB's system-versioned tables keep row history automatically — no triggers, no shadow tables. How FOR SYSTEM_TIME works, what storage growth really costs, and the limitations worth knowing first.