why everyone wants NOSQL other than large-scale Oracle Clusters?

Question

oracle has a good reputation for handling large-scale applications and it's also flexible to extend to cluster environment. Why everyone wants NOSQL?

because nosql db is much cheaper? why not swith object-oriented db?

Answer 1

Firstly, not everyone does want NoSQL. Packaged software (eg ERP) is all pretty much mainstream RDBMS stuff. Don't confuse the amount of development effort with the usage.

What has happened is that NoSQL has opened up a whole range of applications that simply didn't suit relational technologies, and so there's been a rush of applications that CAN be developed. Most of the stuff that could be developed on RDBMS platforms already has been and is in more of a maintenance/upgrade phase. Probably with less upgrading than usual because of the whole global financial climate.

So in ten/fifteen years, as those NoSQL apps move into the same level of maturity, the frenzy will have died down and there's be less excitement.

Answer 2

A SQL solution isn't necessarily what you want regardless of scale. There are situations where you can't easily predict the schema of your model, or worst still your data is schemaless. In those situations you want a data model which doesn't limit you but rather allows you the flexibilty you need to evolve your data while still maintaining core abilities such as fast indexes.

Another reason is that SQL doesn't represent the natural way in which you want to look at your data, predominantly graph DBs such as Neo4J or GraphDB allow developers or users to approach a linked graph model in a more intuitive way.

Of course there is a way to address all these issues in Oracle RDBMS, but it feels more like hacking the DB to fit your needs as opposed to using a DB that fits you. This sounds like a perk but it actually goes a long way into the ease of development and analysis of your application.

Now if we are talking about scale, Oracle can probably beat column based DBs such as HBase or Hypertable, but it is important to note that Oracle RDBMS isn't just more expensive it's way way more expensive. In today's world even small time startups have Terabytes of data they need to analyze daily. Even small companies can use clusters of 100 machines in the cloud to store their data, in such a company Oracle isn't a viable option the annual licensing cost and the hiring of DBAs will prevent startups from using it.

Finally the last reason why you would start off with NoSQL is speed, bringing up a MongoDB and starting development can be done in 5 minutes and sometimes you wanna handle problems as they come up and avoid premature optimization