#distributed-systems

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The outbox pattern without a relay

The transactional outbox solves the dual write problem and hands you a second one: a relay service you have to deploy, watch and keep pointed at the right database. ulak moves the relay into PostgreSQL as background workers. This is how it claims, delivers and recovers, and the trade it asks you to accept for that.

postgresqloutboxdistributed-systems+2 more

Sep 3, 202612 min16 min

~/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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