Evaluate Lock Contention with Non-Blocking Advisory Lock Test

Test Lock Contention with pg_try_advisory_lock

Write a PostgreSQL query to test if an advisory lock can be acquired without waiting using pg_try_advisory_lock.

Solution:

-- Attempt to acquire an advisory lock without waiting.
SELECT pg_try_advisory_lock(67890); -- Returns true if the lock is acquired, false otherwise.

Explanation:

• Purpose of the Query:
• The goal is to test for lock contention by trying to acquire an advisory lock without waiting.
• This demonstrates how pg_try_advisory_lock can be used to determine lock availability.
• Key Components:
• pg_try_advisory_lock(67890) : Tries to obtain the advisory lock with the given key and returns a boolean result.
• Real-World Application:
• Useful in scenarios where the application should proceed only if the necessary resource lock is immediately available.

Notes:

• If the function returns false, the lock is already held by another session.
• Use this approach to implement non-blocking logic for resource management.

For more Practice: Solve these Related Problems:

• Write a PostgreSQL query to attempt acquiring an advisory lock using pg_try_advisory_lock with key 67890 and check the boolean result.
• Write a PostgreSQL query to test if a composite advisory lock can be acquired without waiting using pg_try_advisory_lock with two parameters.
• Write a PostgreSQL query to attempt acquiring an advisory lock on a resource and, if unsuccessful, output a custom message using CASE statements.
• Write a PostgreSQL query to simulate lock contention by attempting pg_try_advisory_lock in two different sessions and observe the outcomes.

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Previous PostgreSQL Exercise: Set a Statement Timeout to Abort Long Lock Waits.