Storage

Algorithms Behind Modern Storage Systems

What's the focus of the work that you're doing today?

I can tell you about Apache Cassandra and the patches I was working on recently. In Apache Cassandra, I've been recently working on transaction replication. Before that, I was working on SASI, an implementation of secondary indexes, on the commit log and on various storage and consistency related things. I had a chance to work on most of the Apache Cassandra subsystems. In Cassandra (or in Apache projects in general) people often don’t specialize (meaning that you work not only on one small subsection of it but you work on the project as a whole). There are few people who specialize on complex subsystems like compaction or other things but it's not very often. Usually, you get to work on the database as a whole. And this was pretty much what I was lucky enough to do.

What are you going to focus on in your talk?

I'm going to focus on the distinction between the two storage types that I think are most prevailing at the moment: immutable and mutable storage. It seems to be that over the years, as the storage systems evolved, database community concentrated more on the mutable storage (the storage which was more suitable for spinning disks, like B-trees). Right now, people tend to move to something that is working slightly better for SSDs (meaning LSM-trees).