.tip

Mar 30, 2026 · one of the small things

dig +short answers the DNS question without the essay

nslookup and plain dig print a whole page for one record.

dig +short api.example.com
dig +short api.example.com @1.1.1.1    # ask a specific resolver
dig +short -t TXT _dmarc.example.com

During a migration, comparing your resolver's answer with a public one's is the quickest way to spot stale DNS.

shelloperations

~/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

esc close