Secure Resources with an Application-Level Advisory Lock

Acquire an Advisory Lock

Write a PostgreSQL query to acquire an advisory lock using pg_advisory_lock for custom application-level locking.

Solution:

-- Acquire an exclusive advisory lock with a specific key.
SELECT pg_advisory_lock(12345); -- The numeric key represents the lock identifier.

Explanation:

• Purpose of the Query:
• The goal is to obtain an application-level lock that is not tied to a specific table row.
• This demonstrates how to use advisory locks to manage custom concurrency scenarios.
• Key Components:
• pg_advisory_lock(12345) : Requests an exclusive lock using the provided key.
• Real-World Application:
• Useful in scenarios where resources need to be locked across multiple tables or systems without using standard row/table locks.

Notes:

• Advisory locks must be explicitly released, or they will be held until the session ends.
• They offer flexibility for implementing custom locking logic.

For more Practice: Solve these Related Problems:

• Write a PostgreSQL query to acquire an exclusive advisory lock with a key value of 98765 using pg_advisory_lock.
• Write a PostgreSQL query to acquire an advisory lock with a composite key (e.g., two integers) using pg_advisory_lock.
• Write a PostgreSQL query to obtain an advisory lock for a resource in the Reports table using a specific numeric key.
• Write a PostgreSQL query to acquire an advisory lock in a transaction and then check if subsequent queries are blocked from acquiring the same lock.

Have another way to solve this solution? Contribute your code (and comments) through Disqus.

Previous PostgreSQL Exercise: Simulate a Deadlock Scenario.
Next PostgreSQL Exercise: Release an Advisory Lock.