Postgres
Renaming a column without downtime: expand, migrate, contract
ALTER TABLE ... RENAME COLUMN takes a millisecond and breaks every running pod. A step-by-step expand and contract rename in Postgres, with the trigger we use.
Database engineer
Ilse Brandt
Ilse looks after Postgres for a payments team: migrations, indexes, vacuum and the queries nobody wants to own. She writes about EXPLAIN output and schema changes that do not take the site down.
Stories by Ilse
Postgres
The index that did nothing: reading an EXPLAIN plan line by line
We added an index to fix a 1.2 second query and the plan did not change. Here is how EXPLAIN ANALYZE told us why, and the partial index that worked.
Reliability
Idempotency keys for webhooks: the ten lines that stop double charges
Webhook providers deliver at least once, so your handler will see duplicates. A unique key and one transaction in Postgres make that harmless.