Database Reference
In-Depth Information
• Relational databases impose a schema even before we put any data into the
database, and even if a schema is too rigid. Many of us work in domains
whereitisverydificulttoapplyasingledatabaseschematoalltheelements
of the domain that we are working with. Increasingly, we are seeing the need
foralexibletypeofschemathatwouldcatertoamoreiterative,moreagile
way of developing software.
As you will see in the following sections, the next generation of database management
systemsisdeinitelynotsettlingforwhatwehavetoday,andisattemptingto
push innovation forward by providing solutions to some of these extremely
complex problems.
NoSQL databases
The new millennium and the explosion of web content marked a new era for database
management systems as well. A whole generation of new databases emerged, all
categorized under the somewhat confrontational name of NOSQL databases. While
it is not clear where the naming came from, it is pretty clear that it was born out of
frustration with relational systems at that point in time. While most of us nowadays
treat NOSQL as an acronym for Not Only SQL, the naming still remains a somewhat
controversial topic among data buffs.
The basic philosophy of most NOSQL adepts, I believe, is that of the "task-oriented"
database management system. It's like the old saying goes:
if all you have is a
hammer, everything looks like a nail
. Well, now we have different kinds of hammers,
screwdrivers, chisels, shovels, and many more tools up our sleeve to tackle our
data problems. The underlying assumption then, of course, is that you are better off
using the right tool for the job if you possibly can, and that for many workloads, the
characteristics of the relational database may actually prove to be counterproductive.
Other databases, not just SQL databases, are available now, and we can basically
categorize them into four different categories:
• Key-Value stores
• Column-Family stores
• Document stores
• Graph databases
Let's get into the details of each of these stores.
