couchdb-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Kenneth Kalmer <>
Subject Re: Some guidance with extremely slow indexing
Date Sat, 11 Apr 2009 18:58:11 GMT
On Thu, Apr 9, 2009 at 5:17 PM, Paul Davis <>wrote:

> Kenneth,
> I'm pretty sure you're issue is in the reduce steps for the daily and
> montly views. The general rule of thumb is that you shouldn't be
> returning data that grows faster than log(#keys processed) where as I
> believe your data is growing linearly with input.
> This particular limitation is a result of the implementation of
> incremental reductions. Basically, each key/pointer pair stores the
> re-reduced value for all [re-]reduce values in its children nodes. So
> as your reduction moves up the tree the data starts exploding which
> kills btree performance not to mention the extra file I/O.
> The basic moral of the story is that if you want reduce views like
> this per user you should emit a [user_id, date] pair as the key and
> then call your reduce views with group=true.
> HTH,
> Paul Davis

Hi Paul

Thanks for taking the trouble of investigating for me, I'll dive into the
views and clean them up a bit according to your advice as well as brush up
on the caveat you explained. I saw other threads in the archives where you
gave similar advice, sorry for not realizing I stepped into the same trap.
When I've got the issue resolved I'll update the gist and we can leave it as
a point of reference for others.

Thanks again!

Kenneth Kalmer

  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message