Databricks-Spark-Assoc Using Spark SQL Practice Question
Which of the following describes the behavior of a Delta table when a 'DELETE' operation is performed?
⚠ Common exam trap
Candidates often assume DELETE drops the entire table or runs an instant metadata-only operation, forgetting that Delta Lake must physically rewrite the specific data files containing target rows.
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
✓
It identifies affected files, rewrites them excluding the target rows, and updates the transaction log.
Delta Lake implements deletes by rewriting only the files containing the data to be removed, while maintaining a record of the change in the transaction log. This is much more efficient than traditional systems that might perform full table scans or require complex locking. Understanding this 'copy-on-write' or 'merge-on-read' approach is vital for Databricks developers to predict performance and costs when executing large-scale DML operations.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
It deletes the entire table and recreates it without the target rows.
Why it's wrong here
Delta Lake is designed for efficiency and does not rewrite the entire table for a DELETE operation. Instead, it identifies the specific files containing the records that meet the filter criteria, creates new versions of those files, and records the change, minimizing data movement and maximizing performance.
- ✗
It physically removes the data from all files in a synchronous manner.
Why it's wrong here
Delta Lake does not physically remove the data immediately. Instead, it marks the files as deleted in the transaction log. The actual removal of data from storage occurs later during a VACUUM command, allowing for time travel and maintaining ACID consistency during concurrent read operations.
- ✓
It identifies affected files, rewrites them excluding the target rows, and updates the transaction log.
Why this is correct
Delta Lake uses a metadata-driven approach where it only processes the files containing the records to be deleted. By writing new files and updating the transaction log, it ensures ACID compliance and enables time travel, representing the efficient, performant way Delta Lake handles record-level deletions.
- ✗
It only marks the rows as deleted without affecting the underlying files.
Why it's wrong here
This description refers to 'soft deletes', which are not the default behavior for Delta Lake. Delta Lake performs physical data updates by creating new versions of files. While the transaction log keeps track of versions, the data files themselves are modified to reflect the state change at the commit.
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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 Databricks exam blueprint
This Databricks-Spark-Assoc practice question is part of Courseiva's free Databricks 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 Databricks-Spark-Assoc exam.