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From aaron morton <aa...@thelastpickle.com>
Subject Re: Cassandra compression not working?
Date Wed, 26 Sep 2012 02:05:44 GMT
Nothing jumps out. Are you able to reproduce the fault on a test  node ?

There were some schema change problems in the early 1.1X releases. Did you enable compression
via a schema change ?

Cheers

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

On 25/09/2012, at 9:14 AM, Mike <mtheroux2@yahoo.com> wrote:

> I forgot to mention we are running Cassandra 1.1.2.
> 
> Thanks,
> -Mike
> 
> On Sep 24, 2012, at 5:00 PM, Michael Theroux <mtheroux2@yahoo.com> wrote:
> 
>> Hello,
>> 
>> We are running into an unusual situation that I'm wondering if anyone has any insight
on.  We've been running a Cassandra cluster for some time, with compression enabled on one
column family in which text documents are stored.  We enabled compression on the column family,
utilizing the SnappyCompressor and a 64k chunk length.
>> 
>> It was recently discovered that Cassandra was reporting a compression ratio of 0.
 I took a snapshot of the data and started a cassandra node in isolation to investigate.
>> 
>> Running nodetool scrub, or nodetool upgradesstables had little impact on the amount
of data that was being stored.
>> 
>> I then disabled compression and ran nodetool upgradesstables on the column family.
 Again, not impact on the data size stored.
>> 
>> I then reenabled compression and ran nodetool upgradesstables on the column family.
 This resulting in a 60% reduction in the data size stored, and Cassandra reporting a compression
ration of about .38.
>> 
>> Any idea what is going on here?  Obviously I can go through this process in production
to enable compression, however, any idea what is currently happening and why new data does
not appear to be compressed?
>> 
>> Any insights are appreciated,
>> Thanks,
>> -Mike


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