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Dataflow provides a scalable and flexible way to process and clean the incoming data in real-time before loading it into BigQuery.

Cloud Data Fusion is a fully managed, cloud-native data integration service that allows you to build and manage data pipelines with a graphical interface. Wrangler is a feature of Cloud Data Fusion that enables you to interactively explore, clean, and transform data using a spreadsheet-like UI. You can use Wrangler to normalize the data in BigQuery by applying various directives, such as parsing, formatting, replacing, and validating data. You can also preview the results and export the wrangled data to BigQuery or other destinations. You can then set up a recurring job in Cloud Data Fusion to run the Wrangler pipeline on a schedule, such as weekly or daily. This way, you can create a quick and code-free solution to normalize the data for your reports. References:

Cloud Data Fusion overview

Wrangler overview

Wrangle data from BigQuery

[Scheduling pipelines]

When Dataflow fuses multiple transformations into a single stage (step), it can make it harder to pinpoint which specific part of that fused stage is causing a bottleneck because internal metrics for individual ParDos within the fused stage might not be as distinct.

Reshuffle Operation (Option D):Inserting a Reshuffle (or GroupByKey followed by ungrouping, which forces a shuffle) operation between logical processing steps in your Beam pipeline prevents Dataflow from fusing those steps. A shuffle operation acts as a barrier to fusion. This materializes the intermediate PCollection and forces data to be redistributed across workers.

Benefit for Debugging:By breaking the fusion, the Dataflow monitoring UI will display distinct steps for the operations before and after the Reshuffle. This allows you to observe metrics like processing time, throughput, and watermarks for each now-separated step, making it much easier to identify which part of your original fused logic is the bottleneck.

Let's analyze why other options are less effective for this specific problem of afused step:

A (Verify service account permissions):While important for overall pipeline health, permission issues usually result in outright failures or errors in logs, not typically a slowdown within a successfully running (albeit slow) fused step.

B (Insert output sinks):Adding actual output sinks (like writing to Pub/Sub or GCS) after each key step would also break fusion and allow you to measure throughput. However, it's a more heavyweight approach than Reshuffle. It introduces I/O overhead and requires setting up and managing these temporary sinks. Reshuffle is a lighter-weight way to achieve the same goal of breaking fusion for diagnostic purposes within the pipeline itself.

C (Log debug information):Logging can be helpful, but if the entire fused step is slow, logs might not easily distinguish which internal operation is the culprit without very careful and verbose logging. Analyzing potentially massive volumes of logs for performance bottlenecks can be less direct than observing stage metrics in the Dataflow UI once fusion is broken.

Using Reshuffle is a standard technique recommended by Google Cloud for debugging performance issues in fused Dataflow stages.

To re-encrypt all of your CMEK-protected Cloud Storage data after a key has been exposed, and to ensure future writes are protected with a new key, creating a new Cloud KMS key and a new Cloud Storage bucket is the best approach. Here’s why option C is the best choice:

Re-encryption of Data:

By creating a new Cloud Storage bucket and copying all objects from the old bucket to the new bucket while specifying the new Cloud KMS key, you ensure that all data is re-encrypted with the new key.

This process effectively re-encrypts the data, removing any dependency on the compromised key.

Ensuring CMEK Protection:

Creating a new bucket and setting the new CMEK as the default ensures that all future objects written to the bucket are automatically protected with the new key.

This reduces the risk of objects being written without CMEK protection.

Deletion of Compromised Key:

Once the data has been copied and re-encrypted, the old key can be safely deleted from Cloud KMS, eliminating the risk associated with the compromised key.

Steps to Implement:

Create a New Cloud KMS Key:

Create a new encryption key in Cloud KMS to replace the compromised key.

Create a New Cloud Storage Bucket:

Create a new Cloud Storage bucket and set the default CMEK to the new key.

Copy and Re-encrypt Data:

Use the gsutil tool to copy data from the old bucket to the new bucket while specifying the new CMEK key:

gsutil -o "GSUtil:gs_json_api_version=2" cp -r gs://old-bucket/* gs://new-bucket/

Delete the Old Key:

After ensuring all data is copied and re-encrypted, delete the compromised key from Cloud KMS.

Reference Links:

Cloud KMS Documentation

Cloud Storage Encryption

Re-encrypting Data in Cloud Storage

Dataprep is a low code, serverless, and fully managed service that allows users to visually explore, cleanse, and validate data in Cloud Storage. It also provides features such as data profiling, data quality, data transformation, and data lineage. Dataprep is integrated with BigQuery, so users can easily export the prepared data to BigQuery for further analysis or modeling. Dataprep is a suitable solution for the data science team to quickly and easily work with the data in Cloud Storage, without having to write code or manage infrastructure. The other options are not as suitable as Dataprep for this use case, because they either require more coding, more infrastructure management, or more data movement. Loading the data into BigQuery, either directly or through Dataflow, would incur additional costs and latency, and may not provide the same level of data exploration and validation as Dataprep. Creating an external table in BigQuery would allow users to query the data in Cloud Storage, but would not provide the same level of data cleansing and transformation as Dataprep. References:

Dataprep overview

Dataprep features

Dataprep and BigQuery integration