PostgreSQL - Transactions and Concurrency
What will be the result of this query if the advisory lock with key 999 is already held by another session?
SELECT pg_try_advisory_lock(999);
What will be the result of this query if the advisory lock with key 999 is already held by another session?
medium📝 query result Q13 of 15
Step-by-Step Solution
Solution:
Step 1: Understand pg_try_advisory_lock behavior
This function tries to acquire the lock immediately and returns true if successful, false if the lock is held by someone else.Step 2: Analyze the scenario
Since the lock with key 999 is already held, the function returns false without waiting.Final Answer:
false -> Option BQuick Check:
pg_try_advisory_lock returns false if lock busy [OK]
Quick Trick: pg_try_advisory_lock returns false if lock busy [OK]
Common Mistakes:
- Expecting true even if lock is held
- Thinking it returns null or error
- Confusing pg_try_advisory_lock with pg_advisory_lock
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