On Sun, Feb 12, 2012 at 12:01 PM, Joshua Berkus <josh@agliodbs.com> wrote:
> You'd pretty much need to do large-scale log harvesting combined with samples of query concurrency taken several
timesper minute. Even that won't "normalize" things the way you want, though, since all queries are not equal in terms
ofthe amount of data they hit.
>
> Given that, I'd personally take a statistical approach. Sample query execution times across a large population of
serversand over a moderate amount of time. Then apply common tests of statistical significance. This is why Heroku
hasthe opportunity to do this in a way that smaller sites could not; they have enough servers to (probably) cancel out
anyrandom activity effects.
>
Yes, I think if we could normalize, anonymize, and randomly EXPLAIN
ANALYZE 0.1% of all queries that run on our platform we could look for
bad choices by the planner. I think the potential here could be quite
remarkable.
--
Peter van Hardenberg
San Francisco, California
"Everything was beautiful, and nothing hurt." -- Kurt Vonnegut