PostgreSQL
Autovacuum Is Running and Your Table Is Still Bloating
Dead tuples that never get reclaimed, a table twice the size of its data, and queries getting slower every week. Here is what blocks vacuum and how to see it.
MicroVMs
Your Database Got Slower and Nothing in Your Code Changed
Query times doubling at unpredictable hours with no deploy and no traffic spike. When the cause is not in your process, it is usually not on your machine either.
Bug Hunt
Chasing a Race Condition That Disappeared Every Time I Added a Log Line
The classic heisenbug. Here is why observation changed the outcome, and the three techniques that found it anyway.
PostgreSQL
Postgres deadlock detected: Reading the Log and Fixing the Lock Order
Two transactions each hold what the other wants. Here is how to read the deadlock report, find both statements, and restructure so it cannot happen again.
PostgreSQL
Why Your Index Is Not Being Used: Reading EXPLAIN ANALYZE Line by Line
You added the index and the query is still slow. Here is how to read a Postgres query plan properly and find the row estimate error causing it.
Bug Hunt
How a Timezone Bug Silently Corrupted Three Months of Analytics
The dashboard looked right. The numbers were wrong by a few percent every day, and the reason was one implicit conversion in a reporting query.
Networking
Your Webhook Handler Will Be Called Twice and You Should Plan For It
At-least-once delivery means duplicates are normal operation, not an edge case. Here is how to build a handler that survives them.
Databases
Your Cache Is Serving Stale Data and the Bug Is in the Invalidation
Reading from cache is easy. Knowing when to remove something is where the bugs live, and most of them are races.
PostgreSQL
The Database Migration That Locked the Table for Nine Minutes
Adding a column should be instant. Sometimes it is not, and the difference is worth knowing before you run it in production.
Databases
Finding the N+1 Queries You Do Not Know You Have
The code reads beautifully and issues four thousand queries. Here is how to detect them automatically instead of discovering them in production.
PostgreSQL
FATAL: sorry, too many clients already
Connection pooling explained through the failure it prevents, and why raising max_connections is usually the wrong fix.