Databases · Middle · Question 20 of 75

What is a deadlock, and what does PostgreSQL do about it?

1A query that never finishes; PostgreSQL waits forever
✓Correct answer: Two transactions each wait for a lock the other holds; PostgreSQL detects the cycle and aborts one of them with an error
3A table that can no longer be read

Explanation

The aborted transaction should be retried. Prevent deadlocks by locking rows in the same order everywhere and keeping transactions short.

Further reading

PostgreSQL: Explicit locking ↗

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