[postgis-users] How compute the stats from a raster table.

Sandro Santilli strk at keybit.net
Fri Mar 16 01:25:51 PDT 2012

On Fri, Mar 16, 2012 at 08:17:14AM +0100, Andrea Peri wrote:
> >ST_SummaryStats()
> Hi Pierre,
> I try it ,
> but i'm not sure to understand the results.

SELECT (ST_SummaryStats(..)).* FROM ...

Should show you "labels" to better understand.

> If yes, this mean it is returning the stats for every tile.
> And so my quest now is how to retrieve the total stat for all the raster table.

I guess you could run aggregates on the single columns of the stats, like:

WITH stats AS ( SELECT (ST_SummaryStats(..)).* FROM ... )
SELECT sum(count) as count, sum(sum) ... FROM stats;

I guess it could be useful to define an aggregate taking
"SummaryStats" type in input so you could do something like:

SELECT (ST_SummaryStatsAgg(ST_SummaryStats(xx))).* FROM myrast;


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