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Date: Sat, 04 Aug 2012 12:23:46 -0400
From: Dave Brosius <dbrosius@mebigfatguy.com>
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To: user@cassandra.apache.org
Subject: Re: Secondary index impact on write performance
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There is a second (system managed) column family for each secondary 
index, so any write to a field that is indexed causes two writes, one to 
the main column family, and another to the index column family, where in 
this index column family the key is the value of the secondary column, 
and the value is the key of the original row.


On 08/04/2012 11:40 AM, David McNelis wrote:
> Morning,
>
> Was reading up on secondary indexes and on the Datastax post about 
> them, it mentions the additional management overhead, and also that if 
> you alter an existing column family, that data will be updated in the 
> background.  But how do secondary indexes affect write performance?
>
> If the answer is "it doesn't", then how do brand new records get 
> located by a subsequent indexed query?
>
> If someone has a link to a post with some of this info, that would be 
> awesome.
>
> David