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From Sandeep Tata <sandeep.t...@gmail.com>
Subject Re: cassandra's performance?
Date Thu, 04 Jun 2009 01:41:36 GMT
I did mean the transaction log.
Yes, you can't turn it off with a configuration option today, but this
should be a one line fix.

On Wed, Jun 3, 2009 at 6:33 PM, Jonathan Ellis <jbellis@gmail.com> wrote:
> 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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