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From Todd Burruss <bburr...@real.com>
Subject RE: Question about CL.ZERO
Date Mon, 12 Jul 2010 23:23:51 GMT
the goal i am reaching for with ZERO is to return control to the "user" ASAP, with super fast
response times.  the load isn't high at all, but persisting does take time even under light
load.  we are not actually using ZERO at the moment but were considering it for "fire and
forget" type of events.

maybe the risk of overloading a server is not worth it.

________________________________________
From: Benjamin Black [b@b3k.us]
Sent: Monday, July 12, 2010 3:50 PM
To: user@cassandra.apache.org
Subject: Re: Question about CL.ZERO

CL.ONE represents the fastest you can sustain.  CL.ZERO represents
writing to memory on the coordinator, regardless of what the nodes can
sustain for durable writes.  That is a bad situation, regardless of
your durability goals.  So, there is no good reason.

What you are describing is a non-existent CL in which the writes are
dispatched to the replicas and success immediately returned to the
client.  Wouldn't be hard to add.

On Mon, Jul 12, 2010 at 10:51 AM, B. Todd Burruss <bburruss@real.com> wrote:
> why is there no good reason?  if i would like to record informational
> events, possibly for debugging or something, i don't care if they actually
> get saved and i want the client's request to be as fast as possibly.  this
> sounds like a good reason.
>
> are you saying that CL.ONE is equally performant?  or possibly better by
> your comment that ZERO can be a serious resource hog?
>
> thx
>
> On 07/11/2010 11:09 AM, Benjamin Black wrote:
>>
>> And, to be clear, there is no good reason to use CL.ZERO and it can be
>> a serious resource hog on the coordinator.
>>
>> On Sun, Jul 11, 2010 at 9:21 AM, ChingShen<chingshenchen@gmail.com>
>>  wrote:
>>
>>>
>>> Hi all,
>>>
>>>   Does it mean that the coordinator node always return success to the
>>> client
>>> at CL.ZERO? But if the coordinator node sends a request to a given node
>>> B(RF=1), then B is down, what happened? The coordinator node will write
>>> the
>>> hint locally?
>>>
>>> Thanks.
>>>
>>> Shen
>>>
>>>
>

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