Occasionally, you need to compute the Cartesian product of several sets. Java 8 Streams make this simple, clear, elegant… and extravagantly expensive. I’ve created a Cartesian helper class that solves the memory usage problem, and allows Cartesian…

As part of a general effort to improve the security of our infrastructure, all of our AWS instances now have OSSEC installed on them to provide host-based intrusion detection — this includes instances in our autoscaling groups. In this post I’ll explain how this is done.

Hi, my name is Mustafa Haddara, and I’m a Software Developer at Vena. We build a multidimensional database (aka OLAP Cube; the wikipedia article is pretty good at elaborating on the subject). I work mainly on the compiler and runtime for Vena Calcs, our custom…

In honour of Claude Shannon’s 100th birthday, I want to tell you about two ideas I had for storing data efficiently. These ideas are pretty nifty individually, but together, they form a data structure that allows a large…

It’s always been an interesting challenge explaining to a prospective hire all that they will get out of an experience at Vena. I can’t project the future for them, the levelling up it will do for their career, the excitement and challenges they’ll face. It’s something I hope they’ll have a chance to see…

When you’re running a cloud service like we do here at Vena, uptime is very important. We run blue-green deployments and we strive to make all database schema changes backwards compatible, so server upgrades require no downtime and rollbacks are equally painless. The end result is that our users…

At Vena we’ve been recently engaged in an effort to upgrade our servers to take advantage of AWS’s Autoscaling and Elastic Load Balancing (ELB) services, the ability for servers that are in an unhealthy state to be replaced by new healthy servers. During this process we have run into a bit of a problem…