On Wed, Jan 4, 2012 at 10:48 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Matthew Foster <matthew(dot)foster(at)noaa(dot)gov> writes:
> > We have a database with approximately 130M rows, and we need to produce
> > statistics (e.g. mean, standard deviation, etc.) on the data. Right now,
> > we're generating these stats via a single SELECT, and it is extremely
> > slow...like it can take hours to return results.
>
> What datatype are the columns being averaged? If "numeric", consider
> casting to float8 before applying the aggregates. You'll lose some
> precision but it'll likely be orders of magnitude faster.
>
> regards, tom lane
>
Tom,
The data are type double.
Matt