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From Josh Bryan <>
Subject Re: Write Performance
Date Mon, 12 Jan 2009 21:40:00 GMT
I went ahead and ran benchmarks again where I created 100 documents
first using the bulk api, and then added attachments separately.  I did
these tests with couch 0.9.0a733182 (the same 0.9 version I used
previously).  On the dual core pentium, I saw a write rate of 138
documents per second.  This is slightly slower than the 150 / second I
saw when the attachments were included in the bulk request.  Also, on
the quad xeon, I saw a write rate of about 200 / second.  This is about
the same as I saw when attachments were included in the bulk request. 
However, if I ran two instance of couchdb on the xeon machine and
distributed writes across them, the write rate increased to about 360 /
second and utilized all 4 cpus.  It seems that the only way I can get
couchdb to use more cpu's while writing is to actually use multiple
instances of couch.  Anyway, thanks for the ideas.


Josh Bryan wrote:
> This is an interesting idea, and from Damien's note about attachments
> executing in a separate thread, is probably worth looking into.  I'll
> go ahead and run benchmarks on this on Monday.
> --thanks,
> Josh
> Sven Helmberger wrote:
>> Josh Bryan schrieb:
>>> On a dual core pentium 3.0ghz with erlang 5.6 and couch 0.8.0 using
>>> bulk
>>> writes, I get throughput of 95 writes / second .   I didn't get the
>>> 2000
>>> per second that Michael did, but that is likely due to the fact that
>>> his
>>> documents are considerably smaller than mine (each of my docs has a
>>> 4K-10K attachment).  By upgrading to the latest couchdb from svn, this
>>> improved from 95 / second to about 150 / second.
>> My totally unsubstantiated guess would be that if you have lots of
>> attachments you might actually be faster bulk creating the docs
>> without attachments and then adding the attachments later as binary.
>> Regards,
>> Sven Helmberger

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