Enabling Log Compaction

Provides a code example for using timestamps on HPE Ezmeral Data Fabric Event Store streams and topics.

Log compaction is enabled through the HPE Ezmeral Data Fabric Event Store StreamDescriptor interface with the setCompact method where the compact value is set to true. Additionally, use the setDeleteRetentionMS and setMinCompactionLagMS methods to set the time delay before compacting records and the time that deleted records are retained.

Configuration values include:

compact - used to set log compaction at the stream-level.
min.compaction.lag.ms - used to set a minimum time delay (milliseconds) before starting to compact records after they are written. Records won’t get compacted until after this period. The setting gives consumers time to retrieve every record.
delete.retention.ms - used to set the minimum time (milliseconds) that deleted records are retained.

Note: You can set not set log compaction when creating the stream; only when editing the stream configuration. The configuration parameters, min.compaction.lag.ms and delete.retention.ms can be set when both creating and editing streams.

Enabling Log Compaction

The following code example performs the following:

Enables log compaction at the stream-level.
Sets the minumum time delay before log compaction starts
Set the minimum time that deleted record are retained.

// Creates a stream
// Sets log compaction on the stream
// Sets the minimum time for a message to stay uncompacted
// Sets the time that deleted records are retained.

(Admin streamAdmin = Streams.newAdmin(conf)) 
	StreamDescriptor streamDescriptor = Streams.newStreamDescriptor();
       streamDescriptor.setCompact(true);
       streamDescriptor.setDeleteRetentionMS(deleteRetentionMs);
	streamDescriptor.setMinCompactionLagMS(minCompactionLagMs); 
       streamAdmin.editStream(streamName, streamDesc);
}

For More Information

See the following topics for more information: