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From Jason Davies <>
Subject Re: Use couchdb as the data store for real-time chat room
Date Sat, 14 Mar 2009 10:57:01 GMT
Hi Howard,

On 14 Mar 2009, at 10:20, howard chen wrote:

> 1. I know couchdb is good for simple key-value query, but is couchdb
> fast for range requests ? E.g. I want to get all message in between
> Add_Time -  Last_Time? How does it compare with MySQL range query on
> index?

Yes, CouchDB is extremely fast for range requests.  In fact, this is  
CouchDB's sweet spot.  Essentially, CouchDB's views allow you to  
create a B-Tree index (mapping keys to values) and then retrieve  
values from a range of keys (in a linear keyspace) very quickly.     
So, this would be ideal for range requests on documents indexed by  
time, like in your case.  I don't know how comparable such queries are  
with an equivalent on a MySQL index, but it would certainly be  
comparable, and CouchDB gives you a lot more for free (flexible  
schema, replication and in general designed for high scalability) so I  
would recommend giving it a try.

> 2. Is Memcached useless if I am using couchdb?

I'm guessing memcached would still be useful as a caching layer to  
squeeze that extra bit of speed if you have the RAM, but maybe someone  
else can speak from experience.

Jason Davies

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