Oh, and yes, that is the correct link. Dean
From: Marcelo Elias Del Valle <mvall...@gmail.com<mailto:mvall...@gmail.com>> Reply-To: "user@cassandra.apache.org<mailto:user@cassandra.apache.org>" <user@cassandra.apache.org<mailto:user@cassandra.apache.org>> Date: Tuesday, September 18, 2012 10:50 AM To: "user@cassandra.apache.org<mailto:user@cassandra.apache.org>" <user@cassandra.apache.org<mailto:user@cassandra.apache.org>> Subject: Re: Is Cassandra right for me? You're talking about this project, right? https://github.com/deanhiller/playorm I will take a look. However, I don't think using Cassandra's model itself (with CFs / key-values) would be a problem, I just need to know where the advantage relies on. By your answer, my guess is it relies on better performance and more control. I also saw that if I plan to use Data Stax enterprise to get real time analytics, my data would need to be stored in Cassandra's usual format. It would harder for me use PlayOrm if I am planning to use advanced data stax features, like Solr indexing data on Cassandra without copying columns, realtime, wouldn't it? I don't know much of this Solr feature yet, but my understanding today is it wouldn't be aware of the tables I create with playOrm, just of the column families this framework uses to store the data, right? 2012/9/18 Hiller, Dean <dean.hil...@nrel.gov<mailto:dean.hil...@nrel.gov>> Until Aaron replies, here are my thoughts on the relational piece… If everything in my model fits into a relational database, if my data is structured, would it still be a good idea to use Cassandra? Why? The playOrm project explores exactly this issue……A query on 1,000,000 rows in a single partition only took 60ms AND you can do joins with it's S-SQL language. The answer is a resounding YES, you can put relational data in cassandra. The writes are way faster than a DBMS and joins and SQL can be just as fast and in many cases FASTER on noSQL IF you partition your data properly. A S-SQL statement looks like so on playOrm PARTITIONS t(:partitionId) SELECT t FROM Trades as t where t.numShares > 10 You can have as many partitions as you want and a single partition can have millions of rows though I would not exceed 10 million probably. Later, Dean 2012/9/18 aaron morton <aa...@thelastpickle.com<mailto:aa...@thelastpickle.com><mailto:aa...@thelastpickle.com<mailto:aa...@thelastpickle.com>>> 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 <mvall...@gmail.com<mailto:mvall...@gmail.com><mailto:mvall...@gmail.com<mailto:mvall...@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 -- Marcelo Elias Del Valle http://mvalle.com - @mvallebr -- Marcelo Elias Del Valle http://mvalle.com - @mvallebr
