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PROFESSIONAL-DATA-ENGINEER · Question #346

You are running your BigQuery project in the on-demand billing model and are executing a change data capture (CDC) process that ingests data. The CDC process loads 1 GB of data every 10 minutes into a

The correct answer is B. Create a BigQuery reservation for the job.. Option B is correct because BigQuery allows you to assign a reservation directly to a specific job by specifying the reservation_id in the job's configuration. This lets you apply committed-slot capacity (predictable pricing) exclusively to the scan-intensive CDC merge job, while

Submitted by certguy· Mar 30, 2026Building and operationalizing data processing systems

Question

You are running your BigQuery project in the on-demand billing model and are executing a change data capture (CDC) process that ingests data. The CDC process loads 1 GB of data every 10 minutes into a temporary table, and then performs a merge into a 10 TB target table. This process is very scan intensive and you want to explore options to enable a predictable cost model. You need to create a BigQuery reservation based on utilization information gathered from BigQuery Monitoring and apply the reservation to the CDC process. What should you do?

Options

  • ACreate a BigQuery reservation for the dataset.
  • BCreate a BigQuery reservation for the job.
  • CCreate a BigQuery reservation for the service account running the job.
  • DCreate a BigQuery reservation for the project.

How the community answered

(38 responses)
  • A
    3% (1)
  • B
    76% (29)
  • C
    8% (3)
  • D
    13% (5)

Explanation

Option B is correct because BigQuery allows you to assign a reservation directly to a specific job by specifying the reservation_id in the job's configuration. This lets you apply committed-slot capacity (predictable pricing) exclusively to the scan-intensive CDC merge job, while the rest of your project continues running on on-demand billing - giving you surgical cost control exactly where you need it.

Why the distractors are wrong:

  • A (dataset): Datasets are not a valid reservation assignment target in BigQuery. Reservations attach to compute resources, not storage constructs.
  • C (service account): BigQuery does not route reservation assignments by service account identity; this concept doesn't exist in the reservation model.
  • D (project): While project-level reservation assignment is valid, it applies committed slots to all jobs in the project - not just the CDC process - which over-provisions and defeats the goal of targeted cost control.

Memory tip: Think of BigQuery reservation assignments as a targeting hierarchy: Org → Folder → Project → Job. Each level is more specific than the last. When you need to isolate cost for a single workload (like one CDC pipeline), go to the most specific valid target - the job - rather than blanketing the whole project.

Topics

#BigQuery Reservations#Cost Management#Change Data Capture#Data Ingestion

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