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.
The JSON keyword in MariaDB is a compatibility alias over LONGTEXT. It migrates schemas cleanly, then surprises you at scale: full parses per row, whole-document rewrites per update, and equality semantics that differ from MySQL.
MariaDB's InnoDB is a maintained fork with its own defaults: the change buffer is gone in 11.0, flushing defaults to O_DIRECT, the redo log was rewritten, and half of every MySQL tuning guide quietly stops applying.
A two-node Galera cluster survives fewer failures than a single node. Here is the quorum arithmetic behind that, how garbd breaks ties, what a non-primary component actually does to your writes, and how to bootstrap safely after a full outage.
A Galera node rejoin either streams a small delta (IST) or copies the entire dataset (SST), and whether any donor's gcache still holds the joiner's missing writesets decides which. Here is how the decision is made, how to size for…
gcache.size is the difference between a node rejoining in three minutes via IST and a two-hour full SST that hammers the donor. Here is how the ring buffer works, how to size it from wsrep_replicated_bytes, and how to verify the…
An ADD COLUMN on one Galera node froze writes on all three for forty minutes. Here is what TOI really does to the cluster, how to run RSU node by node without aborting one, and the DDL decision runbook.
Someone forgot the WHERE clause. You can restore last night's backup and replay a day of binlog, or you can generate the inverse transaction and apply it in minutes. Here is how MariaDB flashback actually works.
MariaDB can store optimizer statistics as ordinary data in mysql.table_stats, column_stats and index_stats — histograms included. Here is how to turn it on, keep it fresh, and stop guessing why a plan changed.
The audit checkbox says 'encrypt data at rest'; the operations reality is key custody, background rotation threads, a binlog that stays plaintext until you say otherwise, and a recovery plan that dies with the key file. The honest field guide.
Deep OFFSET pagination punishes InnoDB and PostgreSQL alike. Here is how keyset pagination works in each engine, including composite cursors, row-value comparisons, and covering-index tricks.