The Multi-Stage Query Engine is a preview feature available starting in Imply 2022.06. Preview features enable early adopters to benefit from new functionality while providing ongoing feedback to help shape and evolve the feature. All functionality documented on this page is subject to change or removal in future releases. Preview features are provided "as is" and are not subject to Imply SLAs.
All authenticated users can use the Multi-Stage Query Engine (MSQE) through the UI and API if the extension is loaded. However, without additional permissions, users are not able to issue queries that read or write Druid datasources or external data. The permission you need depends on what you are trying to do with the Multi-Stage Query Engine (MSQE).
The permission required to submit a query depends on the type of query:
- SELECT from a Druid datasource requires the READ DATASOURCE permission on that datasource
- INSERT or REPLACE into a Druid datasource requires the WRITE DATASOURCE permission on that datasource
- EXTERN references to external data require READ permission on the resource name "EXTERNAL" of the resource type "EXTERNAL".
Multi-Stage Query Engine tasks are Overlord tasks, so they follow the Overlord's (indexer) model. This means that users with access to the Overlord API can perform some actions even if they didn't submit the query. The actions include retrieving the status or canceling a query. For more information about the Overlord API and MSQE, see Interact with a query.
To interact with a query through the Overlord API, you need the following permissions:
- INSERT or REPLACE queries: You must have READ DATASOURCE permission on the output datasource.
- SELECT queries: You must have read permissions on the
__query_selectdatasource, which is a stub datasource that MSQE creates.
If you enable durable storage for mesh shuffle with S3 as the storage, the following S3 permissions are required:
The following are used for pushing and fetching intermediate stage results to and from S3:
The following is used for removing intermediate stage results: