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From Donal Zang <>
Subject Re: insert slowdown with secondary indexes
Date Sat, 11 Jun 2011 11:40:03 GMT
On 11/06/2011 02:27, wrote:
> I'm trying to understand why doing the inserts into a column family with indexes seems
to jam things up and am wondering if there are any settings that I could tweak to help. It
seems that the 4 node cluster should be able to handle 2 threads of data coming at it.  Has
anyone had any experience with this number of indexes per column family? Any insight or suggestions
would be appreciated.
I used to post an email about this, see the mail list archive.
The secondary index now use hash method, and it causes an random I/O 
when do insertion(so lots of swap work). Also, the query based on it 
would be slow too.
So my advice would be : don't use the secondary index, at least for now 
(there are plans to build an bitmap index [1])
You can try Ed Uff 's method [2] to build an CF as your index, it's much 
faster than the secondary index. (this method may need the CompositeType 


Donal Zang
Computing Center, IHEP
19B YuquanLu, Shijingshan District,Beijing, 100049
86 010 8823 6018

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