Out of curiosity, why is Postgresql's Java support so poor? I am specifically looking for the ability to write triggers in Java.
Because it hasn't been a priority of contributors. This is how non-single-vendor open source projects work: people decide what is important to them and do the work required. If something gets neglected then I guess it wasn't really important.
I took a look at the PL/Java project and it looked both incomplete and dead, yet other languages like Javascript are taking off. I would have expected to see very strong support for Java because it's the most frequently used language on the server-side.
I think Javascript is taking off because JSON is taking off. The problem with Java is that while there are plenty of use cases for it in the db, it isn't something which there are *common* use cases for.
What's going on? Why isn't this a core language supported alongside SQL, Perl and Python as part of the core project?
I have a few questions on this, the answers of which may help answer your question:
1. How well does having a server-side JVM work, resource-wise, when you have a forked process model like PostgreSQL? Does having the additional JVM's pose performance and competition for resources that lighter languages would not?
2. What is your specific use case for a trigger in Java?