A sow_and_delta_subscribe command is used to combine the functionality of commands sow and a delta_subscribe in a single command.

The sow_and_delta_subscribe command is used: (a) to query the contents of a SOW topic (this is the sow command); and (b) to place a subscription such that any messages matching the subscribed SOW topic and query filter will be published to the AMPS client (this is the delta_subscribe command). As with the delta_subscribe command, publish messages representing updates to SOW records will contain only the information that has changed.

If a sow_and_delta_subscribe is issued on a record that does not currently exist in the SOW topic, or if it is used on a topic that does not have a SOW-topic store defined, then a sow_and_delta_subscribe will behave like a sow_and_subscribe command.

Header Fields

The following table contains the header fields supported by a sow_and_delta_subscribe command.

Options Field

The following table contains a list of the Options available and their definitions when used in the AMPS sow_and_delta_subscribe command.


A sow_and_delta_subscribe command returns the following command types:

AMPS will send acknowledgment messages for the following AckType fields: received and processed, along with a populated Status header field describing the acknowledgment message.

If the sow_and_delta_subscribe command is successful, AMPS will return a group_begin message to notify the client that a group of messages is being returned as part of the sow portion of the command. For more information about SOW topic query behavior, see the chapter on Querying the State of the World in the AMPS User Guide. The following table contains the AckType messages which can be returned by a sow_and_delta_subscribe.

The stats acknowledgment message includes three values in the header, the Matches, TopicMatches and the RecordsReturned. These are defined below:


The total number of records compared across all matching SOW topics.


The number of records returned that match the topic regular expression and the content filter. This value can be greater than RecordsReturned in the case where the number of returned records is limited by TopN.


The total number of records returned to the client, which can be limited by the TopN header value.


Errors for a sow_and_delta_subscribe query are either returned in the Status field if an AckType has been defined, or the errors may be inserted into the AMPS log.

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