XACK key group ID [ID …]

Time complexity: O(1) for each message ID processed.

Once a consumer successfully processes a message, it should call 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 Redis server.

The command returns the number of messages successfully acknowledged. Certain message IDs may no longer be part of the PEL (for example because they have been already acknowledge), and XACK will not count them as successfully acknowledged.