On Thu, Mar 11, 2010 at 12:51 PM, Henrik Thostrup Jensen <thost...@gmail.com> wrote: > Hi > > I recently did some performance test of different _id sizes [1], including a > comparison between stock 0.10 and a 0.11 snapshot. Unexpectedly, 0.11 turned > out to be slower for view generation, despite the work done with COUCHDB-495. > I've poked a bit at the problem, and I think the reason (or a part of it), is > the increased number of fsync call during view generation for checkpointing. > In > 0.11, checkpointing is done every second, where it is done around 10-15 > seconds > in 0.10. This increases the disk load and creates large B-trees due to > extensive shadowing (as least that is what I observe). > > Is it possible to configure this interval? Delayed commits is not what i want, > as i want insertions to fsync. I tried changing the three 1000 constants in > the > send_after delays in couch_view_group.erl, but checkpointing was still done > each second (I'm not to strong on Erlang, so I had a bit of problem grokking > the code). In the case of a crash this will only cause a certain part of the > db > to be scanned for the view, so IMHO the checkpointing interval could easily be > set to 60 seconds or so. > > There are a lot of guessing in the above, and I'm not sure of everything. > However as we are accumulating more data the time view generation is starting > to hurt when creating new views, so I'd like to see CouchDB become faster at > this (we expect to do some _id field reducement which should help a bit as > well, but it won't buy us that much). > > Are there any other explanations for the performance regressions? > > Please CC any replies, as I am not subscribed. > > > best regards, Henrik > >
delayed_commits = true ; set this to false to ensure an fsync before 201 Created is returned batch_save_size = 1000 ; number of docs at which to save a batch batch_save_interval = 1000 ; milliseconds after which to save batches are the settings you may want to change in ini. - benoît
