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Manage Warmup Jobs

A VeloDB Cloud cluster keeps hot data in a local cache and reads the rest from remote storage. A warmup job preloads data into a cluster's cache so the first requests do not need to fill the cache from remote storage.

Warm up a cluster when you want to:

  • Prepare a new or resumed cluster before it takes production traffic.
  • Refill the cache after scaling in compute, when cached data beyond the new capacity is evicted.
  • Keep a standby cluster's cache aligned with a busy cluster so it can take over quickly.

Cache warmup is available since version 4.1.8. The Warmup Jobs console entry appears only for warehouses with the supported core versions.

Create a warmup job​

Create a warmup job with SQL, not from the VeloDB Cloud console. Run the WARM UP COMPUTE GROUP statement in the SQL Editor or another SQL client. In the SQL statement, a cluster is named as a compute group.

Warm the destination cluster from another cluster, which copies the cached data set of a source cluster into the destination. Use this to reproduce a warm cluster's cache on a new cluster, or to keep a standby cluster aligned with a busy one.

WARM UP COMPUTE GROUP <destination_cluster> WITH COMPUTE GROUP <source_cluster>;

Or warm specific tables and partitions, when you know which datasets the next queries will read.

WARM UP COMPUTE GROUP <destination_cluster> WITH
    TABLE <table_name>
    AND TABLE <table_name> PARTITION <partition_name>;

The statement returns a job ID. Use it to monitor and manage the job in the VeloDB Cloud console or with SQL. For the full syntax, see WARM UP.

Monitor a warmup job​

  1. Log in to the VeloDB Cloud console.
  2. In the upper-left corner, select the warehouse that contains the job.
  3. In the left navigation pane, under Compute, click Warmup Jobs.
  4. Use Search by ID to find a job, or filter jobs by Type, Sync Mode, or Status.
  5. Click a Job ID to open the job details.

A warmup job reports the following:

FieldMeaning
StatusPENDING, RUNNING, FINISHED, or CANCELLED.
TypeCLUSTER when warming from another cluster, and TABLE when warming specific tables or partitions.
Finished / total batchesHow many data batches are warmed out of the total. Use this to gauge progress.
Create time / finish timeWhen the job started and, once complete, when it finished.
ErrorThe failure reason when a job does not finish.

The equivalent SQL statement is SHOW WARM UP JOB.

Cancel a warmup job​

To stop a running job, find it on the Warmup Jobs page and use Actions to cancel it. Its status changes from RUNNING to CANCELLED. Data already warmed remains in the cache. The equivalent SQL statement is CANCEL WARM UP JOB WHERE id = <id>.

Alert on warmup jobs​

When you warm a destination cluster from a source cluster, VeloDB Cloud can keep the destination cache in sync with the source over time. Two metrics track that sync and can be used as a Warmup alert target. Both are available since v4.1.8 on the v4.x line and v26.0.5 on the v26.x line.

MetricUnitWhat it tracks
Warmup Job Trigger GapmsThe interval between warmup runs. A growing gap means warmup is scheduling behind.
Warmup Job Pending SizebytesThe source-minus-destination data size over the last 5 minutes. A growing value means the destination cache is falling behind the source.

Create a warmup alert from the job's own page, not from the Alerts page: open the job on the Warmup Jobs page, then click Create Alert. For the full alerting workflow, including the other target types and notification channels, see Alerts.

Warmup runs on the SQL layer. Create a warmup job with WARM UP COMPUTE GROUP, then look it up and cancel it from the VeloDB Cloud console or with SQL.