id,summary,reporter,owner,description,type,status,priority,milestone,component,version,resolution,keywords,cc 1976,ST_Intersects() returns false while ST_Intersection returns a geography,mhiper3pg,pramsey,"When running ST_Intersects() with multipolygons, sometimes ST_Intersects() returns false for the intersection, while ST_Intersection() returns a geography (not empty). How to reproduce: loading the geography for the state of Iowa (attached) in a table (with no indexes), and querying for the intersection with a polygon fully contained in the state: {{{ select st_intersects(geog, ST_GeographyFromText('SRID=4326;POLYGON((-95.9 42.9,-95.9 43,-95.8 43,-95.8 42.9,-95.9 42.9))')), st_astext(st_intersection(geog,ST_GeographyFromText('SRID=4326;POLYGON((-95.9 42.9,-95.9 43,-95.8 43,-95.8 42.9,-95.9 42.9))'))) from states where name10='Iowa' }}} yields this result: {{{ st_intersects | st_astext ---------------+------------------------------------------------------------------------------------------------------------------------------- f | POLYGON((-95.9 42.8999999999999,-95.9 42.9999999999999,-95.8 42.9999999999999,-95.8 42.8999999999999,-95.9 42.8999999999999)) (1 row) }}} So, the query with ST_Intersects() returns false (which is wrong), but using ST_Intersection() provides the correct result. Is this behavior normal?",defect,closed,medium,PostGIS 1.5.6,postgis,1.5.X,fixed,,