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From Jonathan Ellis <jbel...@gmail.com>
Subject Re: cassandra's performance?
Date Thu, 04 Jun 2009 01:33:43 GMT
You'd still be hitting the transaction log, though.  (I assume the
logging you were talking about was the log4j kind, because you can't
turn off the xlog without hacking at the code right now.)

-Jonathan

On Wed, Jun 3, 2009 at 8:11 PM, Sandeep Tata <sandeep.tata@gmail.com> wrote:
> Apart from logging, given enough memory, you could get Cassandra to
> behave almost like an in-memory system.
>
> Turning off logging is relatively straightforward.
> If you turn off periodic flushing of memtables and have the thresholds
> high enough (a little more tricky), you're done -- chances are the
> read path and the write path will never hit disk.
>
>
> On Wed, Jun 3, 2009 at 5:48 PM, Jonathan Ellis <jbellis@gmail.com> wrote:
>> Cassandra is not designed to work memory-only.  It's designed designed
>> to use disk for durability and to accommodate using large sets of
>> data, letting the OS use memory as a huge cache for that.  For typical
>> data use patterns (where a relatively small amount is "hot") this will
>> be a much better use of hardware than memory-only.
>>
>> On Wed, Jun 3, 2009 at 7:44 PM, lichun li <lilichun@gmail.com> wrote:
>>> Thank you!
>>> The "how fast is it" section says:"In a nutshell, Cassandra is much
>>> faster than relational databases, and much slower than memory-only
>>> systems or systems that don't sync each update to disk."
>>> Can Cassandra work in a memory-only mode? Can it be done by just
>>> changing configuration?
>>>
>>> On Wed, Jun 3, 2009 at 10:38 PM, Jonathan Ellis <jbellis@gmail.com> wrote:
>>>> We're basically in a roll-your-own benchmark state.  Johan can
>>>> probably give some pointers:
>>>> http://blog.oskarsson.nu/2009/05/vpork.html.  Also see the "how fast
>>>> is it" section here:
>>>> http://spyced.blogspot.com/2009/05/cassandra-03-release-candidate-and.html
>>>>
>>>> -Jonathan
>>>>
>>>> On Wed, Jun 3, 2009 at 3:06 AM, lichun li <lilichun@gmail.com> wrote:
>>>>> I can't find cassandra's performance data, such as throughput. Does
>>>>> anyone know where to find these data?
>>>>>
>>>>> --
>>>>> Sincerely yours,
>>>>>
>>>>> Lichun Li
>>>>> Mobile Life New Media Lab, BUPT
>>>>>
>>>>
>>>
>>>
>>>
>>> --
>>> Sincerely yours,
>>>
>>> Lichun Li
>>> Mobile Life New Media Lab, BUPT
>>>
>>
>

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