Cloudera Docs

Configuring query-level fault tolerance for Trino

Learn how to configure query-level fault tolerance for Cloudera Data Warehouse to enable automatic retries for failed queries in Cloudera Data Warehouse.

Cloudera Data Warehouse fault-tolerant execution mitigates query failures by retrying failed queries automatically. Query-Level retry allows the entire failed query to be rerun by the Cloudera Data Warehouse server in memory without requiring external exchange storage.

Before you begin, note the following:

  • Fault tolerance does not apply to broken queries or other user errors. For example, Cloudera Data Warehouse does not retry a query that fails because its SQL cannot be parsed.
  • Enabling query-level retries causes a result delivery delay. Queries cannot begin returning results as quickly as standard queries with fault tolerance disabled because the Cloudera Data Warehouse engine must spool the entire result set.
  • When set to query-level retry, Cloudera Data Warehouse automatically retries a query up to a maximum of 4 times before failing.
  1. Log in to the Cloudera Data Warehouse web UI as a user with administrator privileges (DWAdmin).
  2. Navigate to the Cloudera Data Warehouse Overview page and click the Virtual Warehouses tab.
  3. Create a new Trino Virtual Warehouse or edit an existing Trino Virtual Warehouse.
    1. For a new Virtual Warehouse, in the Trino Specific Settings section:
      1. Click the Retry Policy drop-down menu and select Query Level.
      2. In the Spooling Buffer Size (MB) field, specify the maximum in-memory buffer size allocated on the coordinator per query. The minimum spooling buffer size is 16 MB, and the maximum is 1024 MB.
      3. Click Create Virtual Warehouse.
    2. For an existing Trino Virtual Warehouse:
      1. Click the action menu () for the Virtual Warehouse and select Details.
      2. Click the Sizing And Scaling tab.
      3. In the Retry Policy drop-down menu, select Query Level.
      4. In the Spooling Buffer Size (MB) field, adjust the buffer size value as needed. The minimum spooling buffer size is 16 MB, and the maximum is 1024 MB.
      5. Click Apply Changes.