Index: src/providers/postgres/qgspostgresprovider.cpp
===================================================================
--- src/providers/postgres/qgspostgresprovider.cpp	(revision 13405)
+++ src/providers/postgres/qgspostgresprovider.cpp	(working copy)
@@ -853,18 +853,13 @@
     QString fieldElem = QString::fromUtf8( PQgetvalue( oidResult, 0, 2 ) );
     int fieldSize = QString::fromUtf8( PQgetvalue( oidResult, 0, 3 ) ).toInt();
 
-    if ( tableoid >= 0 )
+    if ( tableoid > 0 )
     {
-      sql = QString( "SELECT attnum FROM pg_attribute WHERE attrelid=%1 AND attname=%2" )
+      sql = QString( "SELECT d.description FROM pg_description AS d JOIN pg_attribute AS a ON d.objoid=a.attrelid"
+                     " WHERE d.objoid=%1 AND a.attname=%2 AND objsubid=a.attnum" )
             .arg( tableoid ).arg( quotedValue( fieldName ) );
 
       Result tresult = connectionRO->PQexec( sql );
-      QString attnum = QString::fromUtf8( PQgetvalue( tresult, 0, 0 ) );
-
-      sql = QString( "SELECT description FROM pg_description WHERE objoid=%1 AND objsubid=%2" )
-            .arg( tableoid ).arg( attnum );
-
-      tresult = connectionRO->PQexec( sql );
       if ( PQntuples( tresult ) > 0 )
         fieldComment = QString::fromUtf8( PQgetvalue( tresult, 0, 0 ) );
     }
@@ -2940,7 +2935,7 @@
     for ( i = 0; i < PQnfields( res ); i++ )
     {
       int tableoid = PQftable( res, i );
-      if ( tableoid >= 0 )
+      if ( tableoid > 0 )
       {
         oidValue = QString::number( tableoid );
         break;
@@ -3000,16 +2995,49 @@
   valid = false;
   QStringList log;
 
+  QString tableName;
+  QString schemaName;
+
   Result result;
   QString sql;
 
-  if ( !isQuery )
+  // get the geometry column's schema and table
+  if ( isQuery )
   {
+    sql = QString( "select %1 from %2 LIMIT 0" )
+          .arg( quotedIdentifier( geometryColumn ) )
+          .arg( mQuery );
+
+    result = connectionRO->PQexec( sql );
+
+    int tableoid = PQftable( result, 0 );
+    if ( tableoid > 0 )
+    {
+      sql = QString( "SELECT t.relname, n.nspname FROM pg_class AS t JOIN pg_namespace AS n ON t.relnamespace = n.oid"
+                     " WHERE t.oid=%1" )
+            .arg( tableoid );
+
+      result = connectionRO->PQexec( sql );
+      if ( PQntuples( result ) > 0 )
+      {
+        tableName = QString::fromUtf8( PQgetvalue( result, 0, 0 ) );
+        schemaName = QString::fromUtf8( PQgetvalue( result, 0, 1 ) );
+      }
+    }
+  }
+  else
+  {
+    tableName = mTableName;
+    schemaName = mSchemaName;
+  }
+
+  if ( !tableName.isEmpty() )
+  {
     sql = QString( "select type,srid from geometry_columns"
                    " where f_table_name=%1 and f_geometry_column=%2 and f_table_schema=%3" )
-          .arg( quotedValue( mTableName ) )
+          .arg( quotedValue( tableName ) )
           .arg( quotedValue( geometryColumn ) )
-          .arg( quotedValue( mSchemaName ) );
+          .arg( quotedValue( schemaName ) );
 
     QgsDebugMsg( "Getting geometry column: " + sql );