In our article The Pure Relational database is dead there
were a lot of misunderstandings as a result of our poor choice of words. People thought we were bashing the relational model because in their mind that was what
pure meant. I got hit with a lot of poetic insults. I still can't think of an alternative word to use for what I meant. Simple doesn't really do it as even relational databases with just standard types
were far from simple when you consider the planner and all the other stuff going on under the hood to protect you from the underlying storage structure. What I was trying to say is that in the beginning most relational databases
just supported a standard set of types which you could not expand on and most people when they think relational today still think just that. That type of relational database is in my book dead or almost dead.
How did this all start. Well whenever we use something like PostgreSQL to store anything complex -- take your pick: geometry data, tree like structures which we use
ltree for, full-text query constructs, and Yes XML we get bashed by some know-it-all who has a very narrow view of what a relational database should be doing and suggesting we use a NoSQL database, a graph engine or a full text engine or normalize our data more. I have also learned XML is a dirty word to many people. I mistakenly thought XML was a complex type people could
relate to, but turns out they can relate to it so well that it brings up tragic memories I can only equate to Post Traumatic Stress Disorder suffered by war veterans or (early or wrong) technology adopters. That was not
my intent either. XML was just merely an example. I will not say you should use XML in your tables, but I will also not say you should stay clear of it as many people wanted me to say. I will say its use is rare, but it has its place. It has its place just as any other complex type and it has its own special needs for navigation, indexing etc. which many relational databases handle fine enough.