[bhor-sanket]

What changes were proposed in this pull request?

Background

Apache Atlas supports multiple audit repository backends (HBase, RDBMS, InMemory, Cassandra, Noop). The REST API GET /api/atlas/v2/entity/bulk/headers?tagUpdateStartTime={epoch_ms} enables consumers to retrieve entities that had classification (tag) changes within a given time window. This API is used by ClassificationAssociator.Retriever to synchronize classification state across systems.

Problem Statement

• Existing behavior: The API always returns an empty guidHeaderMap when Atlas is configured with the RDBMS audit backend
  (atlas.EntityAuditRepository.impl=org.apache.atlas.repository.audit.rdbms.RdbmsBasedAuditRepository).
• Expected behavior: The API should return entity GUIDs that had classification changes (CLASSIFICATION_ADD, CLASSIFICATION_DELETE, CLASSIFICATION_UPDATE) within the specified time range, matching the HBase
  backend behavior.
• Root cause: RdbmsBasedAuditRepository.getEntitiesWithTagChanges(fromTimestamp, toTimestamp) was a // TODO: stub returning Collections.emptySet().
• Impact: Classification sync via the bulk headers API is completely non-functional on RDBMS-backed Atlas deployments.

How the patch resolves it

The implementation mirrors the HBase backend's behavior using JPA/JPQL against the atlas_entity_audit table.

1. New JPA Named Query (janus-jpa_named_queries.xml)

• DbEntityAudit.getDistinctEntityIdsByActionPrefixAndTimeRange — queries atlas_entity_audit for distinct entity IDs where operation LIKE 'CLASSIFICATION_%' within a half-open time range (fromTimestamp, toTimestamp)
• Uses SELECT DISTINCT obj.entityId to avoid materializing full DbEntityAudit objects
• LIKE 'CLASSIFICATION_%' matches CLASSIFICATION_ADD, CLASSIFICATION_DELETE, CLASSIFICATION_UPDATE but excludes PROPAGATED_CLASSIFICATION_* — exact parity with HBase's
  BinaryPrefixComparator("CLASSIFICATION_")
• Half-open interval [from, to) matches HBase's Scan.setTimeRange() semantics

2. New DAO Method (DbEntityAuditDao.java)

• getDistinctEntityIdsByActionPrefixAndTimeRange(String actionPrefix, long fromTimestamp, long toTimestamp) — executes the named query with parameterized action prefix and time range
• Returns List (entity GUIDs), follows existing error-handling convention

3. Repository Implementation (RdbmsBasedAuditRepository.java)

• Replaced the // TODO: stub with a working implementation using RdbmsTransaction + DbEntityAuditDao pattern (consistent with existing listEventsV2 method)
• Passes "CLASSIFICATION_%" as the action prefix
• Wraps result in HashSet<> to satisfy Set return type

How was this patch tested?

Setup :

• Atlas 3.0.0-SNAPSHOT running with RDBMS (PostgreSQL) backend via Docker compose
• API endpoint: GET /api/atlas/v2/entity/bulk/headers?tagUpdateStartTime={epoch_ms}

Use-cases validation :

• Scenario 1: Classification Add — Added classification to an entity, called API with timestamp captured before the add. Entity GUID returned with classification in response. Passed.
• Scenario 2: Classification Delete — Removed classification from an entity, called API with timestamp captured before the delete. Entity GUID returned in response (reflecting current state without the
  classification). Passed.
• Scenario 3: Classification Update — Updated classification attributes, called API with timestamp before the update. Entity GUID returned with updated classification attributes. Passed.
• Scenario 4: No classification changes (empty result) — Performed a non-classification attribute update, called API. Response returned empty guidHeaderMap. Passed.
• Scenario 5: Time range boundary — Added classification, then called API with a timestamp after the add event. Entity excluded from results as expected. Passed.
• Scenario 6: Multiple entities — Added/removed classifications on 3 different entities. All 3 GUIDs returned in a single API response. Passed.
• Scenario 7: Deduplication — Multiple classification events (add + update) on the same entity. Entity GUID appeared exactly once. Passed.
• Scenario 8: Propagated classification exclusion — Added classification with propagate=true to a parent entity linked via hive_process lineage. Parent entity (direct CLASSIFICATION_ADD) returned. Child
  entity (PROPAGATED_CLASSIFICATION_ADD) excluded — matches HBase behavior. Passed.

Unit testing

• Test class: AuditRepositoryTestBase.java (executed via InMemoryAuditRepositoryTest)

• Tests added:

  • testGetEntitiesWithTagChanges — verifies CLASSIFICATION_ADD, CLASSIFICATION_DELETE, CLASSIFICATION_UPDATE events within the time range return their entity GUIDs
  • testGetEntitiesWithTagChanges_emptyForNoMatchingTimeRange — verifies events outside the queried time window are excluded
  • testGetEntitiesWithTagChanges_deduplicatesEntities — verifies multiple classification events for the same entity produce only one GUID in the result set