Make QgsVectorDataProvider defaults methods more efficient

(cherry-picked from a10b8fc)

Author: nyalldawson

src/core/qgsvectordataprovider.cpp

@@ -367,7 +367,7 @@ void QgsVectorDataProvider::uniqueValues( int index, QList<QVariant> &values, in
   QgsFeature f;
   QgsAttributeList keys;
   keys.append( index );
-  QgsFeatureIterator fi = getFeatures( QgsFeatureRequest().setSubsetOfAttributes( keys ) );
+  QgsFeatureIterator fi = getFeatures( QgsFeatureRequest().setSubsetOfAttributes( keys ).setFlags( QgsFeatureRequest::NoGeometry ) );
 
   QSet<QString> set;
   values.clear();
@@ -422,7 +422,8 @@ void QgsVectorDataProvider::fillMinMaxCache()
 
   QgsFeature f;
   QgsAttributeList keys = mCacheMinValues.keys();
-  QgsFeatureIterator fi = getFeatures( QgsFeatureRequest().setSubsetOfAttributes( keys ) );
+  QgsFeatureIterator fi = getFeatures( QgsFeatureRequest().setSubsetOfAttributes( keys )
+                                       .setFlags( QgsFeatureRequest::NoGeometry ) );
 
   while ( fi.nextFeature( f ) )
   {