cryptoe opened a new pull request, #14527:
URL: https://github.com/apache/druid/pull/14527
## Description
One of the most requested features in druid is to have an ability to
download big result sets.
As part of #14416 , we added an ability for MSQ to be queried via a query
friendly endpoint. This PR builds upon that work and adds the ability for MSQ
to write `select` results to durable storage.
We write the results to the durable storage location
`<prefix>/results/<queryId>` in the druid frame format. This is exposed to
users by
`/v2/sql/statements/:queryId/results`.
The broker now understands how to read frame files from durable storage and
return the results as a `json` format to end users.
We also write the first 3000 rows of the result to task report to enable
preview results for clients like the console.
Users can use this by setting the context flag
`selectDestination:DURABLE_STORAGE` while issuing select q's to MSQ.
Note that `DURABLE_STORAGE` needs to be configured on broker, overlord,
ingestion tasks/indexers captured at :
https://druid.apache.org/docs/latest/multi-stage-query/reference.html#enable-durable-storage
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<hr>
##### Key changed/added classes in this PR
* `SQLStatementResource`
* `QueryResultsFrameProcessor`
* `ControllerImpl`
* `WorkerImpl`
* `DurableStorageInputChannelFactory`
* `DurableStorageOutputChannelFactory`
<hr>
### TODO:
* Add more UT's
User facing docs for both # #14416 and this PR would be raised once this is
merged.
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This PR has:
- [ ] been self-reviewed.
- [ ] using the [concurrency
checklist](https://github.com/apache/druid/blob/master/dev/code-review/concurrency.md)
(Remove this item if the PR doesn't have any relation to concurrency.)
- [ ] added documentation for new or modified features or behaviors.
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- [ ] added Javadocs for most classes and all non-trivial methods. Linked
related entities via Javadoc links.
- [ ] added or updated version, license, or notice information in
[licenses.yaml](https://github.com/apache/druid/blob/master/dev/license.md)
- [ ] added comments explaining the "why" and the intent of the code
wherever would not be obvious for an unfamiliar reader.
- [ ] added unit tests or modified existing tests to cover new code paths,
ensuring the threshold for [code
coverage](https://github.com/apache/druid/blob/master/dev/code-review/code-coverage.md)
is met.
- [ ] added integration tests.
- [ ] been tested in a test Druid cluster.
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