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.
MySQL JSON with generated-column indexes and PostgreSQL JSONB with GIN solve the same problem with different tradeoffs. Field notes on operators, updates, and indexing from someone who has run both.
Updating one key in an 18KB JSON document should not rewrite 18KB into the binlog. MySQL 8.0 can patch documents in place and log just the diff — when the change qualifies, and when it silently does not.
MySQL cannot index a JSON column directly, and the workarounds have sharp edges. Field notes on generated columns, multi-valued indexes, MEMBER OF pruning, and when to stop pretending and promote the field.
Dropping an index is instant; rebuilding it under incident pressure takes hours. Field notes on using MySQL 8.0 invisible indexes as a safety net, plus the audit workflow that finds safe candidates.
ALGORITHM=INSTANT is the best schema-change feature in MySQL 8.0, and the most misunderstood. These field notes cover what qualifies, the 64 row-version limit, and how to check before you ALTER.
Purge lag is usually a pinned read view, not weak purge threads. Here is how to tell the two failures apart, what innodb_purge_threads actually buys, and the alerts that matter.
MySQL ships two unrelated features both called InnoDB compression, and picking the wrong one costs memory, CPU, or both. Here is how each actually works and when either still pays.
innodb_io_capacity is a background I/O budget, not a speed dial. Crank it past your redo-driven need and the page cleaner spends the surplus evicting warm pages you were about to read.
An InnoDB FULLTEXT index is a family of hidden auxiliary tables with its own parser, stopwords, and deferred deletes. Where the edges are, which knobs demand a rebuild, and when to move search out of MySQL.
Every MySQL durability argument comes down to two knobs. What innodb_flush_method and innodb_flush_log_at_trx_commit actually change, what a setting of 2 really risks, and why O_DIRECT is usually but not always right.