Greg Stark wrote: >> It's also applicable for the other stats; histogram buckets constructed >> from a 5% sample are more likely to be accurate than those constructed >> from a 0.1% sample. Same with nullfrac. The degree of improved >> accuracy, would, of course, require some math to determine. > > This "some math" is straightforward basic statistics. The 95th > percentile confidence interval for a sample consisting of 300 samples > from a population of a 1 million would be 5.66%. A sample consisting > of 1000 samples would have a 95th percentile confidence interval of > +/- 3.1%.
Doesn't all that assume a normally distributed random variable? I don't think it can be applied to database table contents without further analysis. Yours, Laurenz Albe -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
