XACK

XACK key group id

Available since

5.0.0

Time complexity

O(1) for each message ID processed.

ACL categories

@write, @stream, @fast

The XACK command removes one or multiple messages from the Pending Entries List (PEL) of a stream consumer group. A message is pending, and as such stored inside the PEL, when it was delivered to some consumer, normally as a side effect of calling XREADGROUP, or when a consumer took ownership of a message calling XCLAIM. The pending message was delivered to some consumer but the server is yet not sure it was processed at least once. So new calls to XREADGROUP to grab the messages history for a consumer (for instance using an ID of 0), will return such message. Similarly the pending message will be listed by the XPENDING command, that inspects the PEL.

Once a consumer successfully processes a message, it should call XACK so that such message does not get processed again, and as a side effect, the PEL entry about this message is also purged, releasing memory from the Redict server.

Examples #

redict> XACK mystream mygroup 1526569495631-0
(integer) 1