You want to implement a lock that multiple sessions can hold simultaneously but prevents exclusive locks. Which function should you use?

hard📝 Application Q9 of 15

PostgreSQL - Transactions and Concurrency

Apg_advisory_lock_shared(key bigint)

Bpg_advisory_lock(key bigint)

Cpg_advisory_xact_lock(key bigint)

Dpg_advisory_unlock(key bigint)

Step-by-Step Solution

Solution:

Step 1: Understand shared vs exclusive advisory locks
Shared locks allow multiple holders simultaneously but block exclusive locks until all shared locks are released.
Step 2: Identify the function for acquiring shared locks
pg_advisory_lock_shared acquires a session-level shared advisory lock allowing concurrent holders.
Final Answer:
pg_advisory_lock_shared(key bigint) -> Option A
Quick Check:
Multiple holders = shared lock function [OK]

Quick Trick: Use pg_advisory_lock_shared for concurrent shared locks [OK]

Common Mistakes:

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