RemovableFeature Table Features¶

RemovableFeature is an extension of the TableFeature abstraction for table features that can be removed.

Contract (Subset)¶

actionUsesFeature(
  action: Action): Boolean

See:

Used when:

validateDropInvariants(
  table: DeltaTableV2,
  snapshot: Snapshot): Boolean

See:

Used when:

ColumnMappingPreDowngradeCommand is requested to removeFeatureTracesIfNeeded
DeletionVectorsPreDowngradeCommand is requested to removeFeatureTracesIfNeeded
... (other commands)
TableFeature is requested to validateFeatureRemovalAtSnapshot
AlterTableDropFeatureDeltaCommand is requested to executeDropFeatureWithCheckpointProtection and executeDropFeatureWithHistoryTruncation

preDowngradeCommand(
  table: DeltaTableV2): PreDowngradeTableFeatureCommand

See:

Used when:

Sealed Trait

RemovableFeature is a Scala sealed trait which means that all of the implementations are in the same compilation unit (a single file).

historyContainsFeature(
  spark: SparkSession,
  table: DeltaTableV2,
  downgradeTxnReadSnapshot: Snapshot): Boolean

historyContainsFeature...FIXME

historyContainsFeature is used when:

AlterTableDropFeatureDeltaCommand is requested to executeDropFeatureWithHistoryTruncation

containsFeatureTraces(
  ds: Dataset[SingleAction]): Boolean

containsFeatureTraces checks out whether the given dataset of actions has got any Action that uses this feature.

containsFeatureTraces is used when:

requiresHistoryProtection: Boolean

requiresHistoryProtection is enabled (true) when this table feature is a ReaderWriterFeatureType.

requiresHistoryProtection is used when:

RemovableFeature is requested to historyContainsFeature and isProtocolRemovingFeatureWithHistoryProtection
AlterTableDropFeatureDeltaCommand is executed