On Dec 10, 2013, at 12:30 PM, Jan Lehnardt <[email protected]> wrote: > Heya Adam, > > I found this on IRC: > > <kocolosk> [Thu 23:43] dch: yeah i recommend a small worker_batch_size for > docs with attachments for other reasons > > Could you elaborate on the other reasons? :) > > Best > Jan > --
Sure: * The entire batch gets blocked on the transfer of a single document with attachments, so in the limiting case you end up with only worker_processes documents being transferred in parallel. * A batch might contain several documents with large attachments; these will be processed in series. With those in mind we've found that we can get the best attachment replication throughput out of our Cloudant clusters when we decrease the batch size (to limit the queue depth) and up the worker_processes count a bit (to improve parallelism). I can't promise that those suggestions are immediately applicable to all Apache CouchDB servers, but the facts motivating the adjustment do hold true in both codebases. Adam
