Data Modeling a distributed application could be a book unto itself. However, I will add, modeling by restriction is basically the entire thought process in Cassandra data modeling since it's a distributed hash table and a core aspect of that sort of application is you need to be able to quickly locate which server owns the data you want in the cluster (which is provided by the partition key).
in specific response to your questions 1) as long as you know the primary key and the column name this just works. I'm not sure what the problem is 2) Yes, the partition key tells you which server owns the data, otherwise you'd have to scan all servers to find what you're asking for. 3) I'm not sure I understand this. To summarize, all modeling can be understood when you embrace the idea that : 1. Querying a single server will be faster than querying many servers 2. Multiple tables with the same data but with different partition keys is much easier to scale that a single table that you have to scan the whole cluster for your answer. If you accept this, you've basically got the key principle down...most other ideas are extensions of this, some nuance includes dealing with tombstones, partition size and order. and I can answer any more specifics. I've been meaning to write a series of blog posts on this, but as I stated, it's almost a book unto itself. Data modeling a distributed application requires a fundamental rethink of all the assumptions we've been taught for master/slave style databases. On Tue, Dec 16, 2014 at 10:46 AM, Jason Kania <jason.ka...@ymail.com> wrote: > > Hi, > > I have been having a few exchanges with contributors to the project around > what is possible with Cassandra and a common response that comes up when I > describe functionality as broken or missing is that I am not modelling my > data correctly. Unfortunately, I cannot seem to find comprehensive > documentation on modelling with Cassandra. In particular, I am finding > myself modelling by restriction rather than what I would like to do. > > Does such documentations exist? If not, is there any effort to create such > documentation?The DataStax documentation on data modelling is far too weak > to be meaningful. > > In particular, I am caught because: > > 1) I want to search on a specific column to make updates to it after > further processing; ie I don't know its value on first insert > 2) If I want to search on a column, it has to be part of the primary key > 3) If a column is part of the primary key, it cannot be edited so I have a > circular dependency > > Thanks, > > Jason > -- [image: datastax_logo.png] <http://www.datastax.com/> Ryan Svihla Solution Architect [image: twitter.png] <https://twitter.com/foundev> [image: linkedin.png] <http://www.linkedin.com/pub/ryan-svihla/12/621/727/> DataStax is the fastest, most scalable distributed database technology, delivering Apache Cassandra to the world’s most innovative enterprises. Datastax is built to be agile, always-on, and predictably scalable to any size. With more than 500 customers in 45 countries, DataStax is the database technology and transactional backbone of choice for the worlds most innovative companies such as Netflix, Adobe, Intuit, and eBay.
