.tip

Jun 14, 2026 · one of the small things

HEAD, when you only need to know it exists

Fetch a 20 MB file just to check it's there and you download 20 MB. HEAD returns the headers and nothing else.

curl -I https://cdn.example.com/build/app.js

You get the same status code, Content-Length and ETag. A health check that sends GET to a heavy endpoint wastes the server's time twice a minute.

http

~/tips/today — 2026-10-19

~cat tips/today

Never build an index on a live table without CONCURRENTLY

postgresqlmigrations

A plain CREATE INDEX takes a lock that blocks every write to the table for the whole build. On a big table that means minutes of outage that look like a hung app.

CREATE INDEX CONCURRENTLY orders_customer_idx ON orders (customer_id);

It's slower and can't run inside a transaction, so you'll have to tell your migration tool. If it fails halfway, it leaves an invalid index behind, so check pg_index.indisvalid and drop it before you retry.

↵ open y yesterday l ls /tips

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