In postgis I'm using the following query to buffer lines to polygons:
UPDATE rivers SET poly = ST_Multi(ST_Buffer(lines, 0.01)) where id = 1;
The column 'lines' is a MultiLine and the column 'poly' is a MultiPoly. In record #1 'lines' contains 92 overlapping Line types. I would expect the result of St_Buffer to be a MultiPoly, but it is just a Polygon (If I run the above query without St_Multi I get a sql error. What am I doing wrong?