The correct sequence is B because:
- Combine chunks - First, you need to combine the chunked text data into a unified dataset
- Convert to DataFrame - Then convert the combined data into a DataFrame format that can be processed by Spark
- Write to Delta Lake in Overwrite mode - Finally, write the DataFrame to Delta Lake using Overwrite mode, which is efficient for initial data loading and replaces any existing data
This approach is efficient because:
- Combining chunks first avoids creating multiple small files
- Converting to DataFrame enables Spark's distributed processing
- Overwrite mode is optimal for initial data loading scenarios where you want to replace existing data
Other options are incorrect:
- A includes unnecessary schema definition and uses Merge mode which is for upsert operations
- C converts to DataFrame before combining, which is inefficient for chunked data
- D creates schema separately and uses Append mode which is for adding to existing data