On Wed, Jan 4, 2012 at 10:48 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
Matthew Foster <matthew.foster@noaa.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.