About three years ago I started to build what was really a graph inside a relational database. My thinking at the time was quite simple: every connection between two nodes is a kind of many-to-many relationship, so if I have a table for the nodes and a table for the relationships between them, it should work. When we got to around 500 million rows, nodes and relationships together, the system completely collapsed. We were running it on the largest virtual machine we could get on AWS, which cost about 15 to 20 thousand dollars per month, and a simple query to find one relationship between two nodes was taking about 15 minutes.

After that we moved to graph databases, first ArangoDB, then Neo4j, and now we are using NebulaGraph (I wrote about the move from ArangoDB to NebulaGraph in an earlier article ).…