Carbonado, Graphs, FUSE, Merge-Join and assorted stuff

This month in tech... before that, here's a testimonial for an open source project that you can't beat:

You could've been rich - My mother

Moving on, I heard about a persistence API called Carbonado on the Voldemort forums. It's an open source project from the Amazon guys. It's a no frills (read clean and simple) layer that works with Berkley DB and JDBC. It's even blessed by the BDB guys as a nicer layer on top of BDB.

Here's a decent presentation on graph algorithms from the Hadoop summit. Not very detailed, more like best practices and hints. And here's a nice illustration of PageRank using Javascript.

An interesting thread going on between the Hotspot GC team and a HBase engineer facing some GC problems. Have a look at the new generation sizes they've used for some deployments, it was new to me.

If you want to OD on JVM options, there's a list for that too.

Some folks playing with the userland filesystem in Unix - FUSE. Voldemort, Github and all sorts of funny stuff as Filesystems. Reminds me of GDrive.

NoSQL systems are notorious for not being able to do simple Joins. Their answer is Map-Reduce. For running multi-attribute filtering, there's Merge-Join. Google's App Engine which is like a poor man's data store suggests the same (slide 30). I am skeptical of such queries that run on a cluster of machines, without any indexes, burning CPU on all machines, moving data back and forth. Can't imagine what it does to latency.