I'm wondering if an aggregate function can return a set of records?
Say I have a table with a column of type raster (PostGIS). I want to get the number of times the pixel values 1, 3 and 4 occur in that raster column. I am hoping to build an aggregrate function that returns the following...
value | count
--------+--------
1 | 12
Is it possible for an aggregate function to return a set? I've written some test cases and it looks like the answer is No but I'd like confirmation.
Thanks,
Bborie Park
PostGIS Steering Committee