DBS-C01 Monitoring and Troubleshooting Practice Question
A database specialist is troubleshooting a performance issue on a self-managed PostgreSQL database that they plan to migrate to Amazon RDS. The database has a high number of 'idle in transaction' connections. What is the impact of these connections on the database?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
They hold locks and prevent cleanup of dead tuples, leading to bloat.
Idle-in-transaction connections hold locks and prevent PostgreSQL's autovacuum from cleaning up dead tuples, leading to table bloat and performance degradation. Option A is wrong because idle transactions do not cause constant polling; CPU usage remains low. Option C is wrong because they do not prevent new connections from being established unless the max_connections limit is reached. Option D is wrong because idle transactions do not significantly increase write-ahead logging.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
They increase CPU usage due to constant polling.
Why it's wrong here
Idle connections consume minimal CPU.
- ✓
They hold locks and prevent cleanup of dead tuples, leading to bloat.
Why this is correct
Idle transactions keep locks and prevent autovacuum from marking dead tuples.
- ✗
They prevent new connections from being established.
Why it's wrong here
Connection limits are separate; idle transactions do not block new connections.
- ✗
They cause increased disk I/O from write-ahead logging.
Why it's wrong here
Idle transactions may hold back cleanup but do not directly increase I/O.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DBS-C01 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DBS-C01 exam.