Reservation Assignments
BigQuery offers different compute models that impact access to various compute features and directly affect costs. Masthead analyzes usage to determine the optimal model among On-demand, Standard and Enterprise editions.
Reservation assignments can be configured at different levels:
On-demand (default): Billed per data processed
Project-level assignment: Billing project assigned to a reservation
Query-level assignment: Query with specific reservation (overrides project settings)
These levels provide flexibility to optimize compute models across your workloads. Read more about combining different compute billing models.
Reservation Assignment Levels
Masthead provides recommendations to optimize compute costs through reservation assignments at multiple levels:
Project-level: All workloads in a project use assigned reservations
DAG node-level: Flexible assignment for individual dbt or Dataform models
Pipeline-level: Individual pipelines assigned to specific reservations
Before applying changes, Masthead ensures your workloads are compatible with the target compute model and suggests the reservation capacity adjustments.
Creating or adjusting a reservation for the migrated workload
If you didn't have a reservation, create one in the BigQuery admin project:
CREATE RESERVATION `{BQ_ADMIN_PROJECT}.region-{region_id}.{RESERVATION_ID}` OPTIONS (
edition = STANDARD,
slot_capacity = 0,
autoscale_max_slots = {estimated_slot_capacity}
);If your current workload already uses reservations, you'll need to adjust the reservation capacity as shown above to increase/decrease the capacity for an existing reservation.
Project-Level Reservation Assignment
Masthead analyzes and aggregates all compute workload running within a project to recommend the most cost-effective compute model. We consider overall project usage patterns and potential savings by switching between On-Demand and Editions models with project-level reservation assignments.
DAG Node-Level Reservation Assignment
Flexible reservation assignment at the DAG node level delivers significant savings with minimal effort. Ready-to-use solutions are available for common orchestration technologies to assign reservations to individual models or actions.
dbt - Assign reservations at the model level with dbt Reservations package
Dataform - Assign reservations at the action level with Dataform Reservations package
Airflow - Override reservation assignment at the query level using the example below:
reservation_id = 'RESERVATION_ID'
sql_with_overridden_reservation = f"""SET @@reservation='{reservation_id}';
{your_sql}
"""
BigQueryInsertJobOperator(
task_id="run_query",
configuration={
"query": {
"query": sql_with_overridden_reservation
}
},
...
)
Pipeline-Level Reservation Assignment
Masthead provides a granular view of compute costs, grouped by pipeline. This enables optimization through pipeline-level reservation assignments, migrating pipelines between BigQuery Editions and On-Demand models based on slot-consumption and usage patterns.
Recommendation:
Review pipeline-specific recommendations on Compute Cost Insights page. It shows current and alternative costs achievable by switching the compute model for each pipeline.
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