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. > And FWIW, for sites where we monitor pg_stat_statements, we reset daily > or weekly. Otherwise, the stats have no meaning. I have wondered if we (PG) should do that by default.. I agree that often they are much more useful when reset periodically. Of course, having actual historical information *would* be valuable, if you could identify the time range covered.. Thanks, Stephen
signature.asc
Description: Digital signature