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From Attila Nagy <...@fsn.hu>
Subject Re: CouchDB slow response times
Date Fri, 20 Apr 2012 10:03:44 GMT
Hi,

What I need is a multi-site replicated document DB (well, most of the 
time a key-value DB would also be fine, but CouchDB views are very handy 
for the rest, which spares me to build my own indexes) where I can read 
and write all instances every time and the last modification wins -whole 
document-.
Also, I don't like read repair, the DB should log the changes and 
replicate them (having last update conflict resolution is fine as said) 
to the others when they can be reached.
For this specific application the read/write ratio is very high, like 
5M:1 or higher.

So CouchDB is a perfect fit, my only problem is it (for this particular 
case the read performance) should be somewhat faster. Also, a different 
API would be good, with the attributes of -say- LDAP:
- binary for quick processing
- multiple outstanding queries on the wire

HTTP is easy to use, but I guess it adds somewhere 30-50% of the current 
processing time (are there any exact measurements maybe?).

I really think that april 1 post about switching to Java would bring 
more boost (at least raw performance wise, from other perspectives, 
maybe Erlang is a good fit).
Waiting some hundred milliseconds for the GCs is fine with me if they 
don't happen too often. ;)

On 04/20/12 10:27, Mike Kimber wrote:
> Performance is relative and effective performance is very much determined by the use
case i.e. we do analytics with couchdb its faster than a traditional RDBMS in many cases (especially
if your views are queried regularly) on less hardware (disk space not included, but that's
a trade off and compression in 1.2 helps greatly here) and is easier to use for document analysis.
However it may not be a great fit for very high read use cases currently. If that's your use
case then there are other options i.e. Redis (possibly as a front end to Couch) or dare I
say it here Mongodb and Couchbase or numerous other commercial options from in-memory databases
to column orientated databases, but again it depends on the use case.
>
> You may want to describe your use case i.e. what you are trying to accomplish to  allow
the community to provide  informed comment on your observations.
>
> Thanks
>
> Mike
>
> -----Original Message-----
> From: Attila Nagy [mailto:bra@fsn.hu]
> Sent: 20 April 2012 08:35
> To: user@couchdb.apache.org
> Subject: Re: CouchDB slow response times
>
> On 04/19/12 08:28, Attila Nagy wrote:
>> So getting an exact document took .098921 seconds (nearly 98.9
>> milliseconds) on a completely idle machine.
>>
>> Any subsequent queries are in the order of the above response time,
>> which is just slow.
>>
>> Is this what CouchDB and Erlang capable of, or something is wrong in
>> my setup? I haven't turned compression off, BTW, but will measure its
>> effect.
> Without compression:
> 07:43:03.822390 HTTP GET /test/1
> 07:43:03.823475 HTTP/1.1 200 OK
> 07:43:03.919761 the JSON data
> so the response time is .097371 seconds (97.37 ms)
>
> In the mean time, I've found that somewhere in time CouchDB/HTTPd turned
> TCP NODELAY to off, so
> socket_options = [{nodelay, true}]
> gives: 2.47 ms response time, which is a major increase.
> I could lower that down to 2.1 ms by switching to
> null_authentication_handler, which is not good, but better.
>
> On query performance: when I fetch the same documents (one by one, ID
> number one to the last) from three different machines on four threads on
> each of them (so 12 concurrent HTTP GETs can be on the wire), I can
> saturate one CPU core (Xeon X5670 @ 2.93GHz, I've limited it to one
> core) to 100% CouchDB and can get about 1700 query/sec performance.
> These are just plain HTTP GETs, so no JSON parsing is involved.
> Switching to persistent connections gives 2200 query/sec (again, CouchDB
> maxes the CPU out).
>
> I hope some day CouchDB will be able to deliver performance too.


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