postgres provider: ignore system columns

(cherry picked from commit aa377a0)

Author: jef-n

src/providers/postgres/qgspostgresconn.cpp

@@ -321,7 +321,7 @@ void QgsPostgresConn::addColumnInfo( QgsPostgresLayerProperty& layerProperty, co
   // TODO: optimize this query when pk candidates aren't needed
   //       could use array_agg() and count()
   //       array output would look like this: "{One,tWo}"
-  QString sql = QString( "SELECT attname, CASE WHEN typname = ANY(ARRAY['geometry','geography','topogeometry']) THEN 1 ELSE null END AS isSpatial FROM pg_attribute JOIN pg_type ON atttypid=pg_type.oid WHERE attrelid=regclass('%1.%2')" )
+  QString sql = QString( "SELECT attname, CASE WHEN typname = ANY(ARRAY['geometry','geography','topogeometry']) THEN 1 ELSE null END AS isSpatial FROM pg_attribute JOIN pg_type ON atttypid=pg_type.oid WHERE attrelid=regclass('%1.%2') AND attnum>0" )
                 .arg( quotedIdentifier( schemaName ) )
                 .arg( quotedIdentifier( viewName ) );
   //QgsDebugMsg( sql );