.tip

Mar 4, 2026 · one of the small things

--first-parent reads a merge-heavy history as a timeline

On a branch that merges feature branches in, a plain log mixes together every commit from every feature. --first-parent only follows the main line, so you get one entry per merge.

git log --first-parent --oneline main

That's the release history the way a person would tell it, and git bisect --first-parent searches it the same way.

git

~/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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