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.
InnoDB FULLTEXT and PostgreSQL tsvector both promise search without a search engine. Here is how indexing, ranking, and language support actually compare, and when neither is enough.
Foreign keys feel free until the parent row gets hot. InnoDB's FK checks take shared locks on the parent, cascades multiply your lock footprint, and the contention never names the FK as the cause.
Both engines have ENUM, and both implementations will eventually make you regret something. Field notes on the sorting traps, the ALTER pain, and why a lookup table often wins in either engine.
Doublewrite really does write every flushed page twice, and the honest cost lands somewhere between unmeasurable and painful depending on your flush pattern. Here is how to measure it on your own hardware instead of quoting folklore.
A full disk turns MySQL into a stalled or aborted server, and the wrong rm makes it unrecoverable. This is the playbook: what actually grows, what you can purge safely, and the emergency order of operations.
ORDER BY col1 ASC, col2 DESC forced a filesort for two decades of MySQL. Since 8.0, a composite with a real descending part resolves it straight from the index — if the directions match exactly.
The ORM-generated subquery in FROM looked harmless until it materialized two million rows into a temp table. How MySQL decides between merging and materializing a derived table, and the rewrites that actually fix it.
Your MySQL knowledge is an asset on PostgreSQL, but only after translation. This is the first-week mental-model guide: psql habits, catalogs, roles, config files, the vacuum mindset, and the sharp edges to respect early.
MySQL gives you DATETIME and TIMESTAMP, each with its own timezone story and one with a 2038 ceiling. Here is how they map onto PostgreSQL's timestamp and timestamptz without corrupting history.
MySQL gives every connection a thread; PostgreSQL gives every connection a process. That one difference changes capacity planning, pooling strategy, and what breaks under transaction pooling.