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