prometheus/prometheus — pull request #228 by matttproud (2013-05-07 14:34:10+00:00)
Title: Schedule the background compactors to run.

This commit introduces three background compactors, which compact
sparse samples together.

1. Older than five minutes is grouped togther into chunks of 50 every 30
minutes.

2. Older than 60 minutes is grouped together into chunks of 250 every 50
minutes.

3. Older than one day is grouped together into chunks of 5000 every 70
minutes.