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.
Raising max_connections is the most common MySQL tuning move and usually the wrong one. Here is how thread-per-connection actually costs you, why Threads_running is the real signal, and how to size app pools and ProxySQL with actual math.
The CLONE plugin turned replica provisioning from a multi-tool XtraBackup ritual into two SQL statements. Field notes on setup, the remote clone gotchas, and how to watch progress while it runs.
A JOIN between columns with different charsets or collations can quietly turn an index lookup into a full scan. Field notes on how the coercion rules work, the utf8mb3/utf8mb4 upgrade trap, and the queries that find every mismatched column.
The change buffer turns cold secondary-index page reads into deferred merges. On the right workload it is the reason writes keep up; on NVMe with in-memory indexes it does almost nothing.
Debezium tailing a MySQL binlog and a PostgreSQL logical decoding pipeline look similar from Kafka. Underneath, snapshots, schema changes, and retention fail in opposite ways.
A restart with a cold buffer pool can turn into a twenty-minute incident. How innodb_buffer_pool_dump_pct, scheduled dumps, load status checks, and readiness gates make restarts boring.
MySQL replicates logical change events from the binlog; PostgreSQL streams physical WAL. That one design difference changes lag measurement, consistency guarantees, and what your replicas can be.
Row-based binary logging is the right default, but it makes binlog volume a function of how many rows you touch. This covers FULL vs MINIMAL row images, partial JSON logging, expiry settings, and the big-UPDATE binlog explosion.
binlog_expire_logs_seconds makes old files eligible for purge — it does not promise disk headroom, and it does not protect an offline replica. What pins purging, how to purge safely, and how to size retention from write rate.
mysqldump, XtraBackup, and the clone plugin map surprisingly well onto pg_dump, pg_basebackup, and pgBackRest. The concepts transfer; the tools, PITR mechanics, and failure modes do not.