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hardSystem Design

SKIP LOCKED for job queues — how do you build a concurrent queue without race conditions?

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01

Understand the problem

Use FOR UPDATE SKIP LOCKED with a CTE UPDATE … RETURNING to atomically claim jobs for many workers.

skip-lockedqueueconcurrency
02

Attempt it yourself

Sketch your approach before reading the solution — that's what interviews test.

Nudge consolestandby

Stuck? Beam a request up — the console returns a conceptual nudge that guides your logic without spoiling the implementation.

03

Study the solution

SELECT … FOR UPDATE SKIP LOCKED LIMIT 1 skips rows locked by other workers instead of blocking. Combine with a CTE that UPDATE status='processing' RETURNING * to claim atomically — no double-processing, no polling races.

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04

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