Relational databases, such as MySQL, PostgreSQL and various commercial products, have served us well for many years. Lately, however, there has been a lot of discussion on whether the relational model is reaching the end of its life-span, and what may come after it.

Should you care? Which database technology should you be using?

Of course the answer is “it depends”, but that’s not very helpful. Let me ask you a few questions to help you figure out which technology is appropriate to your particular application. Then I can give a few pointers so that you can find out more.

First of all, calm down. Chances are that your current database is perfectly fine for now. But you might want to keep an eye open in case you notice some symptoms which show that you are pushing the relational model to its limits. Some symptoms relate to the structure of your data:

Do you have tables with lots of columns, only a few of which are actually used by any particular row?

Do you have “attribute” tables where each row is a triple of (foreign key to row in another table, attribute name, attribute value) and you need ugly joins in your queries to deal with those tables?

Have you given up on using columns for structured data, instead just serialising it (to JSON, YAML, XML or whatever) and dumping the string into your database?

Does your schema have a large number of many-to-many join tables or tree-like structures (a foreign key that refers to a different row in the same table)?

Do you find yourself frequently needing to make schema changes so that you can properly represent incoming data?