Databricks Certified Data Engineer - Associate
Get started today
Ultimate access to all questions.
In order for Structured Streaming to reliably track the exact progress of the processing so that it can handle any kind of failure by restarting and/or reprocessing, which of the following two approaches is used by Spark to record the offset range of the data being processed in each trigger?
Real Exam
Community
KKeng
A
Checkpointing and Write-ahead Logs
B
Structured Streaming cannot record the offset range of the data being processed in each trigger.
C
Replayable Sources and Idempotent Sinks
D
Write-ahead Logs and Idempotent Sinks
E
Checkpointing and Idempotent Sinks
Explanation:
Explanation
Correct Answer: A (Checkpointing and Write-ahead Logs)
Structured Streaming uses two key mechanisms to reliably track processing progress and handle failures:
1. Checkpointing
- Purpose: Periodically saves the state of the streaming computation to durable storage
- Function: If the streaming computation fails, it can be restarted from the last checkpoint and resume processing from where it left off
- What it stores: Metadata about the streaming query, including the progress of processing (offsets)
2. Write-ahead Logs (WAL)
- Purpose: Records all changes made to a dataset before they are applied
- Function: Allows Structured Streaming to recover from failures by replaying the write-ahead logs from the last checkpoint
- How it works: Ensures that no data is lost even if the system crashes between checkpoints
Why Other Options Are Incorrect:
B: Incorrect - Structured Streaming can and does record offset ranges through checkpointing and WAL.
C: While replayable sources and idempotent sinks are important concepts in streaming systems, they are not the primary mechanisms Spark uses to record offset ranges for failure recovery.
D: Write-ahead logs are correct, but idempotent sinks alone don't track offset ranges for recovery.
E: Checkpointing is correct, but idempotent sinks handle duplicate data processing rather than tracking offset ranges.
Key Insight:
The combination of checkpointing (for periodic state saving) and write-ahead logs (for continuous change recording) provides the reliability guarantees needed for Structured Streaming to handle failures while maintaining exactly-once processing semantics.
Comments
Loading comments...