Options for Delta Subscribe

The delta subscribe command accepts several options that are unique to delta subscriptions. These options control the precise behavior of delta messages:

Option	Result
no_empties	Do not send messages if no data fields have been updated. By default, AMPS will publish a delta for every publish to the record, even if the data has not changed. By specifying this option, AMPS will only send messages when there is changed data.
no_sowkey	Do not include the AMPS generated SowKey with messages. By default, AMPS includes this key to help you identify unique records within the SOW.
send_keys	Include the SOW key fields in the message. Since the SOW key fields indicate which message to update, without this option, updates to delta messages will never contain the SOW key fields. For views, the SOW key fields are the fields specified in the Grouping element. AMPS accepts this option for backward compatibility. As of AMPS 4.0, this option is included on delta subscriptions by default.
oof	AMPS will deliver out of focus messages on this subscription. When focus tracking is enabled, AMPS will also deliver the full message to a subscription when a previously out-of-focus message comes into focus.

Delta subscriptions also support the options provided for regular subscriptions, including the timestamp option and the conflation options described in the section on Conflated Subscriptions.