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From aaron morton <aa...@thelastpickle.com>
Subject Re: Is Cassandra right for me?
Date Tue, 18 Sep 2012 11:07:55 GMT
> Also, I saw a presentation which said that if I don't have rows with more than a hundred
rows in Cassandra, whether I am doing something wrong or I shouldn't be using Cassandra. 
I do not agree with that statement. (I read that as rows with ore than a hundred _columns_)

> I need to support a high volume of writes per second. I might have a billion writes per
hour
Thats about 280K /sec. Netflix did a benchmark that shows 1.1M/sec http://techblog.netflix.com/2011/11/benchmarking-cassandra-scalability-on.html

> I need to write non-structured data that will be processed later by hadoop processes
to generate structured data from it. Later, I index the structured data using SOLR or SOLANDRA,
so the data can be consulted by my end user application. Is Cassandra recommended for that,
or should I be thinking in writting directly to HDFS files, for instance? What's the main
advantage I get from storing data in a nosql service like Cassandra, when compared to storing
files into HDFS?
You can query your data using Hadoop easily enough. You may want take a look at DSE from 
http://datastax.com/ it makes using Hadoop and Solr with cassandra easier. 

> If I don't need to perform complicated queries in Cassandra, should I store the json-like
data just as a column value? I am afraid of doing something wrong here, as I would need just
to store the json file and some more 5 or 6 fields to query the files later.
Store the data in the way that best supports the read queries you want to make. If you always
read all the fields, or it's a canonical record of events storing as JSON may be best. If
you often get a few fields, and maybe they are updated, storing each field as a column value
may be best. 

> Does it make sense to you to use hadoop to process data from Cassandra and store the
results in a database, like HBase? Once I have structured data, is there any reason I should
use Cassandra instead of HBase?
It depends on how many moving parts you are comfortable with. Same for the questions about
HDFS etc. Start with the smallest about of infrastructure. 

Hope that helps. 

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

On 18/09/2012, at 10:28 AM, Marcelo Elias Del Valle <mvallebr@gmail.com> wrote:

> Hello,
> 
>      I am new to Cassandra and I am in doubt if Cassandra is the right technology to
use in the architecture I am defining. Also, I saw a presentation which said that if I don't
have rows with more than a hundred rows in Cassandra, whether I am doing something wrong or
I shouldn't be using Cassandra. Therefore, it might be the case I am doing something wrong.
If you could help me to find out the answer for these questions by giving any feedback, it
would be highly appreciated. 
>      Here is my need and what I am thinking in using Cassandra for:
> I need to support a high volume of writes per second. I might have a billion writes per
hour
> I need to write non-structured data that will be processed later by hadoop processes
to generate structured data from it. Later, I index the structured data using SOLR or SOLANDRA,
so the data can be consulted by my end user application. Is Cassandra recommended for that,
or should I be thinking in writting directly to HDFS files, for instance? What's the main
advantage I get from storing data in a nosql service like Cassandra, when compared to storing
files into HDFS?
> Usually I will write json data associated to an ID and my hadoop processes will process
this data to write data to a database. I have two doubts here:
> If I don't need to perform complicated queries in Cassandra, should I store the json-like
data just as a column value? I am afraid of doing something wrong here, as I would need just
to store the json file and some more 5 or 6 fields to query the files later.
> Does it make sense to you to use hadoop to process data from Cassandra and store the
results in a database, like HBase? Once I have structured data, is there any reason I should
use Cassandra instead of HBase?
>      I am sorry if the questions are too dummy, I have been watching a lot of videos
and reading a lot of documentation about Cassandra, but honestly, more I read more I have
questions. 
> 
> Thanks in advance.
> 
> Best regards,
> -- 
> Marcelo Elias Del Valle
> http://mvalle.com - @mvallebr


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