It must have come very far in the past few months then...based on my experimentation, it was far from being ready for production use if you needed anything beyond the most basic of SQL queries. That said, I'm rooting for it (and now, caravel). We use Pentaho, and it's....meh. A lot of moving parts, a big learning curve, and a user experience that's just ok. I'm hoping Metabase (and now Caravel) will both succeed...the open source BI space could really use an influx of simpler, beautiful tools.
A side note: I love that Caravel is written in Python. Metabase switched from Python to Clojure, and I personally believe that to be a barrier to entry for contributing. I've started down the Clojure path a number of times only to stop because I see it as something which would be difficult to impose on my team...Lisp is just so different from what most enterprisey development teams are used to. Python, on the other hand, is easier to justify. I've found things I wanted to help fix in Metabase, but having to learn idiomatic Clojure just to submit a patch is a turn-off.
If you don't mind, I'd love to hear why you felt we were far from being ready for production.
Our main challenge has trading off ease of installation and use with the inevitable feature creep that causes the lots of moving parts and learning curve you find meh about Pentaho. You're right in that we've focused on making the most basic of sql queries (via our non-sql tool) usable by anyone in the company on their own vs essentially producing an analytics SDK like Pentaho/Jaspersoft.
On the language front, we made a conscious decision to optimize for ease of installation and low maintenance overhead. While I agree, it's made contributing less accessible, it's been amazing how porting has made Metabase more stable and easier to install. We run a bunch of instances for people, and our ops footprint has been silly small.
I'd love to...but I can't recall the password I used when I set up the h2 db my attempts are stored in and smtp password recovery isn't working (I probably didn't configure it).
If I recall, it was difficult to understand how to properly format the results of a raw sql query to graph. Also, even once properly graphing, saving the graph to a dashboard wouldn't scale properly and would render in a very jumbled manner. Perhaps these issues have been fixed with newer versions....I'll give it another look next week.
