Several methods from IndexerMetadataStorageCoordinator, namely
getUsedSegmentsForIntervalgetAllUsedSegmentsgetUsedSegmentsAndCreatedDatesgetUsedSegmentsForIntervalsgetveUnusedSegmentsForInterval
Duplicate the MetadataSegmentManager's functionality and look like much better suited for the latter class.
The conceptual difference is that MetadataSegmentManager caches the segments' data in memory, while IndexerMetadataStorageCoordinator always accesses the metadata store. This difference should be retained, but there should be comments to those methods, as well as parallel methods returning cached metadata with warnings and guidance regarding which method to use. For example, MaterializedViewSupervisor uses the methods from IndexerMetadataStorageCoordinator which seems unnecessary to me (could use the methods from MetadataSegmentManager instead).
If we decide that "cached metadata - direct access to metadata store" is the separation principle between IndexerMetadataStorageCoordinator and MetadataSegmentManager, then this fact should be reflected in these interfaces' names, Javadocs, and retrieveAllDataSourceNames() method should be moved from MetadataSegmentManager to IndexerMetadataStorageCoordinator.
Several methods from
IndexerMetadataStorageCoordinator, namelygetUsedSegmentsForIntervalgetAllUsedSegmentsgetUsedSegmentsAndCreatedDatesgetUsedSegmentsForIntervalsgetveUnusedSegmentsForIntervalDuplicate the
MetadataSegmentManager's functionality and look like much better suited for the latter class.The conceptual difference is that
MetadataSegmentManagercaches the segments' data in memory, whileIndexerMetadataStorageCoordinatoralways accesses the metadata store. This difference should be retained, but there should be comments to those methods, as well as parallel methods returning cached metadata with warnings and guidance regarding which method to use. For example,MaterializedViewSupervisoruses the methods fromIndexerMetadataStorageCoordinatorwhich seems unnecessary to me (could use the methods fromMetadataSegmentManagerinstead).If we decide that "cached metadata - direct access to metadata store" is the separation principle between
IndexerMetadataStorageCoordinatorandMetadataSegmentManager, then this fact should be reflected in these interfaces' names, Javadocs, andretrieveAllDataSourceNames()method should be moved fromMetadataSegmentManagertoIndexerMetadataStorageCoordinator.