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From Edward Capriolo <edlinuxg...@gmail.com>
Subject Re: Large results and network round trips
Date Thu, 25 Oct 2012 20:54:28 GMT
For this scenario, remove disk speed from the equation. Assume the row
is completely in Row Cache. Also lets assume Read.ONE. With this
information I would be looking to determine response size/maximum
requests second/max latency.

I would use this to say "You want to do 5,000 reads/sec, on a GigaBit
ethernet, and each row is 10K, in under 5ms latency"

Sorry that is impossible.




On Thu, Oct 25, 2012 at 2:58 PM, sankalp kohli <kohlisankalp@gmail.com> wrote:
> I dont have any sample data on this, but read latency will depend on these
> 1) Consistency level of the read
> 2) Disk speed.
>
> Also you can look at the Netflix client as it makes the co-ordinator node
> same as the node which holds that data. This will reduce one hop.
>
> On Thu, Oct 25, 2012 at 9:04 AM, Edward Capriolo <edlinuxguru@gmail.com>
> wrote:
>>
>> Hello all,
>>
>> Currently we implement wide rows for most of our entities. For example:
>>
>> user {
>>  event1=>x
>>  event2=>y
>>  event3=>z
>>  ...
>> }
>>
>> Normally the entires are bounded to be less then 256 columns and most
>> columns are small in size say 30 bytes. Because the blind write nature
>> of Cassandra it is possible the column family can get much larger. We
>> have very low latency requirements for example say less then (5ms).
>>
>> Considering network rountrip and all other factors I am wondering what
>> is the largest column that is possible in a 5ms window on a GB
>> network.  First we have our thrift limits 15MB, is it possible even in
>> the best case scenario to deliver a 15MB response in under 5ms on a
>> GigaBit ethernet for example? Does anyone have any real world numbers
>> with reference to package sizes and standard performance?
>>
>> Thanks all,
>> Edward
>
>

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