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 schema with 40 utf8mb4 VARCHAR(255) columns failed to create on MySQL with ERROR 1118 while PostgreSQL accepted the equivalent table without comment, then rejected its index with a 2704-byte limit nobody had heard of. Both engines store big values…
A 40-minute analytics query on a PostgreSQL standby started dying with 'canceling statement due to conflict with recovery' every night at 02:00. MySQL replicas never cancel your query; they just fall behind. Here is the trade-off both engines make and…
A nightly job ran twice at 02:00 because GET_LOCK was held on the old MySQL primary and the failover moved the lock namespace with nothing in it. Advisory locks are application-level mutexes with no row attached, and each engine scopes,…
Our usage-billing rollup double-counted the fallback hour one November night because date_trunc bucketed in the session time zone and that day had 25 hours. The storage model, the AT TIME ZONE type flip, and the session-zone rules that ended DST…
The read-only analytics role worked for a year, then broke on a Monday with ERROR: permission denied for table charge_events — because the GRANT only covered tables that existed on Friday, and the default privileges had been set for the…
A routine failover promoted the standby in forty seconds — then p99 latency ran at 300 ms for twenty-five minutes while the new primary re-read its working set from disk. The blks_read measurement, pg_prewarm and autoprewarm setup, and the restart…
A report query flipped from an index range scan to a full scan over a weekend, with zero deploys and zero data imports. Both engines re-estimated the same table and got different answers. Here is how MySQL and PostgreSQL gather…
p99 latency spiked every five minutes like clockwork on PostgreSQL, and MySQL stalled hard once a night during batch. Same disease on both: dirty-page flushing falling behind dirty-page creation. Here is how each engine's write-ahead log forces checkpoints, and how…
Our nightly 40GB partner feed loaded in 52 minutes with batched INSERTs and 7 minutes with the native bulk loader. LOAD DATA INFILE and COPY are the fastest write paths either engine has, and they differ on security, replication, and…
A bulk UPDATE of 1.8 million rows took 41 minutes instead of 3 because of one audit trigger, and the replica had a different opinion about the result than the primary. Here is how MySQL and PostgreSQL triggers actually differ:…