Databricks-DA-Assoc Importing Data Practice Question
A data analyst runs COPY INTO to load new CSV files from an S3 path into a Delta table every night. One night the job completes successfully but the row count does not change, even though new files were placed in the source path. The files have the same names as files loaded previously. What is the most likely cause?
⚠ Common exam trap
The trap here is assuming that replacing a file's contents under the same path will cause COPY INTO to reload it, when path-based tracking means it is skipped.
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
✓
COPY INTO skips files whose paths were already loaded unless the load is forced or the files are modified.
COPY INTO is idempotent by design: it records the paths it has loaded and skips them on subsequent runs unless the files are new or the load is explicitly forced. Because the new files reused prior names, their paths matched the load history, so no rows were added despite a successful job status.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The CSV files were written with a different compression codec, so COPY INTO could not parse them.
Why it's wrong here
A codec mismatch would typically cause a parse or read error, not a silent success with zero new rows. COPY INTO surfaces format problems as failures or malformed-record counts. Since the job completed without error and the row count simply did not move, the explanation must be about files being skipped, not about unreadable content.
- ✓
COPY INTO skips files whose paths were already loaded unless the load is forced or the files are modified.
Why this is correct
COPY INTO tracks which file paths it has already ingested and by default does not reload them, even if the underlying object was replaced with new content. Because the new files reused previous names, their paths matched already-processed entries, so the command silently skipped them. This idempotent behavior is intentional but surprises analysts who overwrite files.
- ✗
The Delta table's transaction log has reached its retention limit and stopped accepting new commits.
Why it's wrong here
Transaction log retention affects time travel and vacuum behavior, not the ability to append new data. If the log truly blocked writes, the COPY INTO command would fail with an error rather than report success. The scenario states the job completed successfully, which rules out a write-blocking condition in the table metadata.
- ✗
Auto Loader had already claimed the files, so COPY INTO is blocked from reading them.
Why it's wrong here
Auto Loader and COPY INTO do not lock files against each other; both read from object storage independently. Auto Loader maintains its own checkpoint state, and COPY INTO maintains its own load history. There is no mutual exclusion mechanism that would cause COPY INTO to skip files merely because a stream once saw them.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
About these practice questions
One of 291 original Databricks-DA-Assoc practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
JA
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-DA-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-DA-Assoc exam.