org.apache.druid.segment.realtime.appenderator

Interface SegmentAllocator

public interface SegmentAllocator

Method Summary

Modifier and Type	Method and Description
SegmentIdWithShardSpec	allocate(InputRow row, String sequenceName, String previousSegmentId, boolean skipSegmentLineageCheck) Allocates a new segment for a given timestamp.

Method Detail

allocate

@Nullable
SegmentIdWithShardSpec allocate(InputRow row,
                                          String sequenceName,
                                          @Nullable
                                          String previousSegmentId,
                                          boolean skipSegmentLineageCheck)
                                   throws IOException

Allocates a new segment for a given timestamp. Even though its name is "allocate", this method is actually idempotent: given the same sequenceName, previousSegmentId, and skipSegmentLineageCheck, the implementation must return the same segment ID.

Parameters:

row - the event which triggered this allocation request

sequenceName - sequenceName for this allocation

previousSegmentId - segment identifier returned on the previous call to allocate for your sequenceName. When skipSegmentLineageCheck is false, this can be null if it is the first call for the same sequenceName. When skipSegmentLineageCheck is true, this will be ignored.

skipSegmentLineageCheck - if true, perform lineage validation using previousSegmentId for this sequence. Should be set to false if replica tasks would index events in same order

Returns:

the pending segment identifier, or null if it was impossible to allocate a new segment

Throws:

IOException