[ DCP ] How to get futur changes/mutations only?



We are experimenting a bit with DCP / UPR (couchbase CE v3.01) and are a bit confused about the way we should ask for futur mutations only

We are looking for something like the “Backfill” option used with TAP

The DCP “doc” (https://github.com/couchbaselabs/dcp-documentation/blob/master/documentation/commands/stream-request.md) , says that “Stream Request” can use the “Start By Seqno” option, but how can we set it to the current/futur Seqno ?

We have been playing with “Branor/couchbase-dcp-consumer” and “couchbaselabs/python-dcp-client” : Any help would be appreciated

(We know that DCP is still not open to the outside world, but we are sure this functionality could be a game changer, and want to make sure we are ready when it does)




There are operations to obtain the current sequence numbers for each vbucket in order to pass them on to the “start by seqno” request option: https://github.com/couchbaselabs/dcp-documentation/blob/master/documentation/commands/failover-log.md

The failover log is also very important during failure handling to determine the operations you are potentially ahead of a replica. Once we make it “public” of course we’re going to provide slightly higher level commands to send those requests and more documentation around what to do in certain cases.


Thank you Michael,

I could be wrong, but I don’t find any “operation” that gives the current sequence numbers for each vbucket in the link you point to

Did you mean : https://github.com/couchbaselabs/dcp-documentation/blob/master/documentation/commands/stats-vbucket-seqno.md




No, I’m referring to the failover log which you can use to get all seqnos for each vbucket (you need to ask all 1024 for the first time, most likely): https://github.com/couchbaselabs/dcp-documentation/blob/master/documentation/commands/failover-log.md