On Wed, Oct 23, 2013 at 9:20 AM, Stephen Frost <sfr...@snowman.net> wrote:
> Josh, > > * Josh Berkus (j...@agliodbs.com) wrote: > > On the other hand, it's still true that a high STDDEV indicates a high > > variance in the response times of a particular query, whereas a low one > > indicates that most are close to the average. While precision math > > might not work if we don't have the correct distribution, for gross DBA > > checks it's still useful. That is, I can answer the question in many > > cases of: "Does this query have a high average because of outliers, or > > because it's consisently slow?" by looking at the STDDEV. > > The concern is actually the reverse issue- often the question is "is > this query ever really slow?", or "when is this query really slow?" and > those questions are not answered by stddev, min, max, nor avg. > How does max not answer "is this query ever really slow?"? But good point, if we have a max, then I think a time-stamp for when that max was obtained would also be very useful. Cheers, Jeff
