* Initial support for bootstrap segments.
- Adds a new API in the coordinator.
- All processes that have storage locations configured (including tasks)
talk to the coordinator if they can, and fetch bootstrap segments from it.
- Then load the segments onto the segment cache as part of startup.
- This addresses the segment bootstrapping logic required by processes before
they can start serving queries or ingesting.
This patch also lays the foundation to speed up upgrades.
* Fail open by default if there are any errors talking to the coordinator.
* Add test for failure scenario and cleanup logs.
* Cleanup and add debug log
* Assert the events so we know the list exactly.
* Revert RunRules test.
The rules aren't evaluated if there are no clusters.
* Revert RunRulesTest too.
* Remove debug info.
* Make the API POST and update log.
* Fix up UTs.
* Throw 503 from MetadataResource; clean up exception handling and DruidException.
* Remove unused logger, add verification of metrics and docs.
* Update error message
* Update server/src/main/java/org/apache/druid/server/coordination/SegmentLoadDropHandler.java
Co-authored-by: Kashif Faraz <kashif.faraz@gmail.com>
* Apply suggestions from code review
Co-authored-by: Kashif Faraz <kashif.faraz@gmail.com>
* Adjust test metric expectations with the rename.
* Add BootstrapSegmentResponse container in the response for future extensibility.
* Rename to BootstrapSegmentsInfo for internal consistency.
* Remove unused log.
* Use a member variable for broadcast segments instead of segmentAssigner.
* Minor cleanup
* Add test for loadable bootstrap segments and clarify comment.
* Review suggestions.
---------
Co-authored-by: Kashif Faraz <kashif.faraz@gmail.com>
* Undocument unused segments retrieval API.
* Mark API deprecated and unstable. Note that it'll be removed.
* Cleanup .spelling entries
* Remove the Unstable annotation
### Description
This pr adds an api for retrieving unused segments for a particular datasource. The api supports pagination by the addition of `limit` and `lastSegmentId` parameters. The resulting unused segments are returned with optional `sortOrder`, `ASC` or `DESC` with respect to the matching segments `id`, `start time`, and `end time`, or not returned in any guarenteed order if `sortOrder` is not specified
`GET /druid/coordinator/v1/datasources/{dataSourceName}/unusedSegments?interval={interval}&limit={limit}&lastSegmentId={lastSegmentId}&sortOrder={sortOrder}`
Returns a list of unused segments for a datasource in the cluster contained within an optionally specified interval.
Optional parameters for limit and lastSegmentId can be given as well, to limit results and enable paginated results.
The results may be sorted in either ASC, or DESC order depending on specifying the sortOrder parameter.
`dataSourceName`: The name of the datasource
`interval`: the specific interval to search for unused segments for.
`limit`: the maximum number of unused segments to return information about. This property helps to
support pagination
`lastSegmentId`: the last segment id from which to search for results. All segments returned are > this segment
lexigraphically if sortOrder is null or ASC, or < this segment lexigraphically if sortOrder is DESC.
`sortOrder`: Specifies the order with which to return the matching segments by start time, end time. A null
value indicates that order does not matter.
This PR has:
- [x] 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.)
- [x] added documentation for new or modified features or behaviors.
- [ ] a release note entry in the PR description.
- [x] 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)
- [x] added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
- [x] 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.
- [x] been tested in a test Druid cluster.
In the current design, brokers query both data nodes and tasks to fetch the schema of the segments they serve. The table schema is then constructed by combining the schemas of all segments within a datasource. However, this approach leads to a high number of segment metadata queries during broker startup, resulting in slow startup times and various issues outlined in the design proposal.
To address these challenges, we propose centralizing the table schema management process within the coordinator. This change is the first step in that direction. In the new arrangement, the coordinator will take on the responsibility of querying both data nodes and tasks to fetch segment schema and subsequently building the table schema. Brokers will now simply query the Coordinator to fetch table schema. Importantly, brokers will still retain the capability to build table schemas if the need arises, ensuring both flexibility and resilience.
There is a current issue due to inconsistent metadata between worker and controller in MSQ. A controller can receive one set of segments, which are then marked as unused by, say, a compaction job. The worker would be unable to get the segment information as MetadataResource.
Abhishek Radhakrishnan
zachjsh
Katya Macedo
Rishabh Singh
Adarsh Sanjeev
317brian
Victoria Lim
Nhi Pham