On Fri, May 30, 2014 at 3:28 PM, Ori Livneh <ori@wikimedia.org> wrote:

On Wed, May 28, 2014 at 11:26 PM, Steven Walling <swalling@wikimedia.org> wrote:

My main question is what the rationale is. Is it to improve query performance on analytics dbs?

I imagine it will help, but it's probably not the primary reason. I imagine Sean would like to have the database in a state of equilibrium such that there are no looming dangers, and no reason in principle why things couldn't just keep running. At the moment the clip of incoming events is prone to sharp fluctuations and there is no protocol in place for handling exhausted server capacity.

Correct.

It's not really about performance since the dataset will be larger than $memory regardless.

Of course, if you guys decide that specific data needs to stay around for ever, that's fine; it helps with capacity planning and we just bite the bullet and ensure sufficient storage space is available. Having a default purge-after-X-months policy for new tables would be the baseline.