Package org.apache.druid.segment.metadata
package org.apache.druid.segment.metadata
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ClassDescriptionAn abstract class that listens for segment change events and caches segment metadata.ColumnTypeMergePolicy defines the rules of which type to use when faced with the possibility of different types for the same column from segment to segment.Classic logic, we use the first type we encounter.Resolves types using
ColumnType.leastRestrictiveType(ColumnType, ColumnType)to find the ColumnType that can best represent all data contained across all segments.Immutable representation of RowSignature and other segment attributes.Config for caching and managing datasource schema on the Coordinator.Coordinator-side cache of segment metadata that combines segments to build datasources.Encapsulates information about a datasource, such as its schema.Utility to generate schema fingerprint which is used to ensure schema uniqueness in the metadata database.Metrics related toSegmentSchemaCacheandSegmentSchemaManager.No-op implementation ofSegmentSchemaCachethat always returns false forNoopSegmentSchemaCache.isEnabled()andNoopSegmentSchemaCache.isInitialized().Coordinator-side configuration class for customizing properties related to the SegmentMetadata cache.ThisQuerySegmentWalkerimplementation is specific to SegmentMetadata queries executed byCoordinatorSegmentMetadataCacheand is in parity withCachingClusteredClient.This class publishes the segment schema for segments obtained via segment metadata query.In-memory cache of segment schema used byCoordinatorSegmentMetadataCache.Handles segment schema persistence and cleanup on the Coordinator.Wrapper overSchemaPayloadPlusclass to include segmentId and fingerprint information.