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by Qadeer Ahmad Khan

Making sense of graph databases

Having worked with Virtuoso graph database for half a year I was excited to be given opportunity to try something new. Although my work with the database involved mainly querying with SPARQL and some graph modeling, it caught enough interest that I wanted to understand a bit more.

My main question was how, exactly, do graph databases perform better than relational databases for graphed data. Is it how they store the data that makes them so good? Or is there just some algorithm-magic that makes graph databases super slick. While pondering over these question, I understood how little I knew about graph databases. In fact I don’t even know when to use and not use graph databases.

While reading up, it took a while before I understood that there are at least two kinds of graph databases: Graph databases based on relational databases (like triple stores) and native graph databases. My analysis is based on comparing native graph databases (primarily Neo4j) with relational databases, but in the last part, I present triple stores.

My questions resulted in several blog posts:

  • First I wanted to find out the use cases of graph databases
  • Then, to be able to compare graph database to relational database performance, I needed to understand how relational database stores and retrieves its data, and how joins work
  • Finally, I compare relational database approaches with the native graph database Neo4j to understand why graph databases works more efficiently on connected data than relational databases. I also look at related work regarding Neo4j performance.
  • While doing my research, I understood that that the graph database field is still in development, so much that the term graph database is not even standardized, and that that there are at least two kinds of graph databases. Virtuoso, for example, is more popularly called a triple store.