Databricks Data Engineer Associate Question 351
Select 2You are using a COPY INTO statement to ingest data from a cloud storage location into a Delta Lake table in Databricks. However, no new data is being added to the target table despite verifying that there are new files in the source location. What could be causing this issue?
- A
The target Delta table enforces idempotency by tracking the files already loaded based on their file paths.
- B
The file format specified in the COPY INTO statement does not match the format of the source files.
- C
The source files have already been processed and recorded in the Delta Lake transaction log.
- D
The COPY INTO statement is missing an explicit WHERE clause to filter the new data.
- E
The destination table is not defined as a Delta table, so COPY INTO cannot perform incremental loads.
Show answer and explanation
Correct answers: A, C
Explanation
COPY INTO in Delta Lake is designed to ensure idempotency and avoid duplicating data by keeping track of the files it has already processed. This tracking is based on file paths recorded in the Delta Lake transaction log. If the source files have already been ingested or the file paths match files previously processed, the COPY INTO statement will skip these files. Understanding how Delta Lake tracks data ingestion is crucial to troubleshooting such issues.
- A. Correct.
Correct. Delta Lake automatically tracks files that have been loaded to ensure idempotency, and will not re-process files with the same paths as those already recorded in the transaction log.
- B. Incorrect.
Incorrect. While a mismatch in file format could cause a syntax error or processing failure, it would not result in the data being silently ignored.
- C. Correct.
Correct. If the source files have already been ingested and recorded in the Delta Lake transaction log, COPY INTO will skip those files to prevent duplication.
- D. Incorrect.
Incorrect. A WHERE clause is optional in a COPY INTO statement and is only needed for filtering specific data. The absence of a WHERE clause does not prevent new files from being processed.
- E. Incorrect.
Incorrect. COPY INTO can load data incrementally into Delta tables, but the issue here is not related to whether the table is defined as a Delta table.