.tip

Aug 1, 2026 · one of the small things

Run the tests that touch what you changed, then everything in CI

Running the full suite on every save is why people stop running tests at all.

vitest --changed        # tests affected by uncommitted changes
vitest --changed main   # affected since main

The test runner walks the import graph to find what depends on the changed files. CI still runs everything, while your local loop runs the relevant slice in seconds.

testingdeveloper-experience

~/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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