Social networks in the database: using a graph database
The Neo4j response to Lorenzo Alberton’s post on social networks in a relational database.
From the post:
Recently Lorenzo Alberton gave a talk on Trees In The Database where he showed the most used approaches to storing trees in a relational database. Now he has moved on to an even more interesting topic with his article Graphs in the database: SQL meets social networks. Right from the beginning of his excellent article Alberton puts this technical challenge in a proper context:
Graphs are ubiquitous. Social or P2P networks, thesauri, route planning systems, recommendation systems, collaborative filtering, even the World Wide Web itself is ultimately a graph! Given their importance, it’s surely worth spending some time in studying some algorithms and models to represent and work with them effectively.
After a brief explanation of what a graph data structure is, the article goes on to show how graphs can be represented in a table-based database. The rest of the article shows in detail how an adjacency list model can be used to represent a graph in a relational database. Different examples are used to illustrate what can be done in this way.
Graph databases and Neo4j in particular offer advantages when used with graphs but the Neo4j post overlooks several points.
Unlike graph databases, SQL databases are nearly, if not always, ubiquitous. It may well be that the first “taste” of graph processing may come via a SQL database and lead users to expect more graph capabilities than a SQL solution can offer.
As Lorenzo points out in his posting, performance will vary depending upon the graph operations you need to perform. True for SQL databases and graph databases as well. Having a graph database doesn’t mean all graph algorithms run efficiently on your data set.
Finally:
A table-based system makes a good fit for static and simple data structures, ….
Isn’t going to ring true for anyone familiar with Oracle, PostgreSQL, MySQL, SQL Server, Informix, DB2 or any number of other “table-based systems.”