Cassandra DB migrations

When doing any application that involves a persistent data storage you usually need a way to upgrade and change your database using a set of scripts. Working with patterns like ActiveRecord you get easy up/down by version migrations. But with cassandra, which traditionally was schemaless, there aren’t that many tools out there to do this.… Read the rest

Dalloc – coordinating resource distribution using hazelcast

A fun problem that has come up during the implementation of cassieq (a distributed queue based on cassandra) is how to evenly distribute resources across a group of machines. There is a scenario in cassieq where writes can be delayed, and as such there is a custom worker in the app (by queue) who watches a queue to see if a delayed write comes in and republishes the message to a bucket later on.… Read the rest