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From aaron morton <aa...@thelastpickle.com>
Subject Re: SSTable Index and Metadata - are they cached in RAM?
Date Thu, 16 Aug 2012 22:06:29 GMT
> What about SSTable index, 
Not sure what you are referring to there. Each row has a in a SStable has a bloom filter and
may have an index of columns. This is not cached. 

See http://thelastpickle.com/2011/07/04/Cassandra-Query-Plans/ or http://www.slideshare.net/aaronmorton/cassandra-sf-2012-technical-deep-dive-query-performance

>  and Metadata?

This is the meta data we hold in memory for every open sstable
https://github.com/apache/cassandra/blob/trunk/src/java/org/apache/cassandra/io/sstable/SSTableMetadata.java

Cheers
  

-----------------
Aaron Morton
Freelance Developer
@aaronmorton
http://www.thelastpickle.com

On 16/08/2012, at 7:34 PM, Maciej Miklas <mac.miklas@gmail.com> wrote:

> Hi all,
> 
> bloom filter for row keys is always in RAM. What about SSTable index, and Metadata?
> 
> Is it cached by Cassandra, or it relays on memory mapped files?
> 
> 
> Thanks,
> Maciej


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