PMLE Practice Question: Collaborating Within and Across Teams to Manage Data and Models
A team is using Delta Lake on Dataproc for their data lake with ACID transactions. They want to version data for ML experiments and roll back to a previous version if needed. Which Delta Lake feature should they use?
⚠ Common exam trap
PMLE often tests confusion between Delta Lake features — candidates may pick schema enforcement or Z-order thinking they provide versioning, when only time travel enables historical queries and rollback.
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
✓
Delta Lake time travel
Delta Lake time travel allows querying previous versions of a Delta table using either a version number or a timestamp, enabling reproducibility for ML experiments and rollback to a prior state. This is the native Delta Lake feature designed for versioning and auditing data changes. It directly satisfies the requirement to version data and roll back.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Delta Lake streaming
Why it's wrong here
Streaming handles incremental reads and writes of Delta tables, not historical version retrieval. It tempts because Delta supports streaming sources and sinks, but reverting an ML experiment to an earlier table state requires time travel, which queries previous commits by version or timestamp.
- ✗
Delta Lake schema enforcement
Why it's wrong here
Schema enforcement rejects writes whose columns do not match the table schema, so it cannot restore earlier table states. It is tempting because it governs write correctness, but versioning and rollback require Delta Lake time travel, which reads prior commits by version number or timestamp.
- ✓
Delta Lake time travel
Why this is correct
Time travel queries Delta table snapshots by version or timestamp, letting the team reproduce an exact training dataset and restore an earlier state via RESTORE. This directly satisfies the versioning and rollback requirement, unlike schema evolution or Z-ordering, which address structure and query performance.
- ✗
Delta Lake optimization (Z-order)
Why it's wrong here
Z-order clustering co-locates related data in the same files to speed up filtered reads; it does not retain prior table versions. It tempts because it is a Delta Lake table optimisation, yet rollback to an earlier version needs time travel over the transaction log.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Google Cloud exam blueprint
This PMLE practice question is part of Courseiva's free Google Cloud 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 PMLE exam.