This is the first in a series of posts describing my impressions of converting a large OLAP server to TokuDB. There’s a lot to tell, and the experiment is not yet complete, so this is an ongoing blogging. In this post I will describe the case at hand and out initial reasons for looking at TokuDB.
Disclosure: I have no personal interests and no company interests; we did get friendly, useful and free advice from Tokutek engineers. TokuDB is open source and free to use, though commercial license is also available.
The case at hand
We have a large and fast growing DWH MySQL setup. This data warehouse is but one component in a larger data setup, which includes Hadoop, Cassandra and more. For online dashboards and most reports, MySQL is our service. We populate this warehouse mainly via Hive/Hadoop. Thus, we have an hourly load of data from Hive, as well as a larger daily load.
There are some updates on the data, but the majority of writes are just mysqlimports of Hive queries.
Usage of this database is OLAP: no concurrency issues here; we have some should-be-fast-running queries issued by our dashboards, as well as ok-to-run-longer queries issued for reports.
Our initial and most burning trouble is with size. Today we use COMPRESSED InnoDB tables (KEY_BLOCK_SIZE is default, i.e. 8). Our data volume sums right now at about 2TB. I happen to know this translates as 4TB of uncompressed data.
However growth of data is accelerating. A year ago we would capture a dozen GB per month. Today it is a 100GB per month, and by the end of this year it may climb to 150GB per month or more.
Our data is not sharded. We have a simple replication topology of some 6 servers. Machines are quite generous as detailed following. And yet, we will be running out of resources shortly: disk space (total 2.7TB) is now running low and is expected to run out in about six months. One of my first tasks in Outbrain is to find a solution to our DWH growth problem. The solution could be sharding; it could be a commercial DWH product; anything that works. Continue reading » “Converting an OLAP database to TokuDB, part 1”