PCA Prometheus Fundamentals Practice Question
Which operator performs a set union in PromQL?
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
✓
or
The 'or' operator returns the union of two vectors.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
unless
Why it's wrong here
unless is set subtraction.
- ✗
join
Why it's wrong here
join is not a standard binary operator.
- ✓
or
Why this is correct
or returns the union.
- ✗
and
Why it's wrong here
and is intersection.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed August 2026 · checked against the official CNCF / Linux Foundation exam blueprint
This PCA practice question is part of Courseiva's free CNCF / Linux Foundation 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 PCA exam.