7 min read
How I Actually Find and Fix Slow PostgreSQL Queries
A practical slow-query incident workflow: find the fingerprint, prove the bottleneck, avoid the tempting wrong fix, and ship the smallest change that actually holds.
Database Field Notes
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.
Featured Guides
Slow query optimization
Find the queries dragging your Postgres down, read their plans, and fix them in order of impact.
Read the guide →Index optimization
Which indexes to add, which to drop, and how to spot redundant index debt before it costs you writes.
Read the guide →Vacuum guide
How autovacuum works, when it falls behind, and how to keep bloat from eating your storage and your buffer cache.
Read the guide →Connection pooling
Sizing pools, PgBouncer modes, and how to stop idle-in-transaction sessions from exhausting max_connections.
Read the guide →Replication monitoring
Track lag, WAL throughput, and replication slots before they turn into stale reads or a full disk.
Read the guide →Browse by Topic
Backups and Durability
9 articlesBackups, restores, PITR, archive gaps, and recovery drills for PostgreSQL.
Cloud Providers
5 articlesAWS RDS, Azure Database for PostgreSQL, Google Cloud SQL, AlloyDB, and managed PostgreSQL monitoring notes.
Connections and Pooling
10 articlesConnection storms, pool saturation, PgBouncer behavior, and max_connections pressure.
CPU, Memory, and I/O
17 articlesCPU, memory, disk, temp files, checkpoints, buffers, and workload pressure.
Indexes
37 articlesIndex design, index debt, reindexing, constraint indexes, and evidence-driven DDL.
Locks and Transactions
22 articlesLock waits, deadlocks, blocking chains, idle transactions, and transaction hygiene.
MariaDB
56 articlesGalera clustering, InnoDB and Aria internals, replication, optimizer behavior, and MariaDB operations notes.
MySQL
107 articlesInnoDB internals, replication, locking, query performance, and MySQL operations notes.
pgvector and RAG
15 articlesHNSW, IVFFlat, recall, embedding search, and production RAG performance notes.
Replication and WAL
28 articlesReplica lag, WAL growth, failover readiness, hot standby behavior, and replication slots.
Slow Queries
38 articlesQuery plans, EXPLAIN ANALYZE, planner regressions, pagination, joins, and statistics.
SQL Server
47 articlesWait statistics, tempdb, Query Store, Always On availability groups, and SQL Server operations notes.
Vacuum and Bloat
16 articlesAutovacuum, dead tuples, bloat, wraparound, MVCC, freeze age, and visibility.
Latest Field Notes
5 min read
Composite Index Column Order: The Decision That Costs Most People a Day
Two columns in a composite index can go in either order. Which order matters more than people expect, and "index everything both ways" is a worse answer than the right call.
5 min read
Partial Indexes in Postgres: The Right Index Is Often a Smaller One
Partial indexes work when the product mostly asks about a predictable slice of a table. They fail when the predicate is vague, parameterized, or not repeated by the query shape.
5 min read
GIN vs GiST in Postgres: Which Index Type to Reach For
GIN and GiST cover the cases B-tree cannot. They overlap, they have very different cost profiles, and the docs are vague about which to use. Here is the practical answer.
5 min read
BRIN Indexes in Postgres: Tiny, Underrated, and Sometimes Exactly Right
BRIN indexes are 100x smaller than B-tree on the right data. They are also useless on the wrong data. The deciding factor is whether the table is naturally sorted.
4 min read
Foreign Keys in Postgres: The Indexes the Database Will Not Make For You
Foreign key constraints check the parent side automatically. The child side is your problem. Forgetting this index is one of the most common silent performance bugs.
5 min read
Expression Indexes in Postgres: The 30-Minute Lesson That Cost Us Three Days
Expression indexes are powerful but exacting. If the query expression and index expression do not match, the index you trusted may not be used.
6 min read
PostgreSQL Partitioning: When to Use It, When to Skip It, and How Not to Mess It Up
Partitioning solves specific problems. It also creates new ones. Here's an honest look at range, list, and hash partitioning — including the mistakes that will haunt you.
4 min read
REINDEX in Postgres: When the Index Got Out of Hand
REINDEX is a repair tool, not an indexing strategy. Use it when bloat, corruption, or access pattern churn makes rebuilding cheaper than carrying the old index forward.
4 min read
Unique Constraints vs Unique Indexes: The Quiet Difference
Both enforce uniqueness. They look identical in `\d`. The differences only show up when you try to alter the table or hit them with a partial uniqueness rule.