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From aaron morton <aa...@thelastpickle.com>
Subject Re: Cassandra as session store under heavy load
Date Wed, 12 Oct 2011 09:10:11 GMT
> - Serializing data is not an option, because I would like to have possibility to access
data using console
fair enough, but I would do some tests to see the difference in performance and disk space

> - Using Cassandra to build something like "HTTP session store" with short TTL is not
an anti-pattern ?
Heavy delete work loads, such as a queue, is more of a problem. You may have to may some extra
attention to disk space, because it not clean up instantly. But I would not go so far to say
anti-pattern.

- There is really no way to tell Cassandra, that particular Key Space should be stored "mostly"
in RAM and only asynchronous backup on HDD (JMS has something like that)?

See the durable_writes option for create keyspace in the CLI. Turn if off and the commit log
is not used, writes will only be committed to disk when the memtable is flushed. 

Have fun. 


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

On 12/10/2011, at 7:28 PM, Maciej Miklas wrote:

> - RF is 1. We have few KeySpaces, only this one is not replicated - this data is not
that very important. In case of error customer will have to execute process again. But again,
I would like to persist it.
> - Serializing data is not an option, because I would like to have possibility to access
data using console
> - I will keep row cache - you are right, there is no guarantee, that my data is still
in Memtable
> 
> I will get my hardware soon (3 servers) and we will see ;) In this worst case I will
switch my session storage to memcached, and leave all other data in Cassandra (no TTL, or
very long)
> 
> Another questions:
> - Using Cassandra to build something like "HTTP session store" with short TTL is not
an anti-pattern ?
> - There is really no way to tell Cassandra, that particular Key Space should be stored
"mostly" in RAM and only asynchronous backup on HDD (JMS has something like that)?
> 
> 
> Thanks,
> Maciej
> 


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