Use a FilterFids request for vector file writer rather than fetching

all features and then testing the feature id when saving selected features For providers such as Postgres this is orders of magnitude faster. Eg, saving 6 selected features from a 800k PostGIS table now takes < 1 second as opposed to ~33 seconds Fix #8334 (cherry-picked from f0d31b0)
qgis · Nov 18, 2015 · 57381f4 · 57381f4
1 parent 14408d3
commit 57381f4
Showing 1 changed file with 2 additions and 5 deletions.
diff --git a/src/core/qgsvectorfilewriter.cpp b/src/core/qgsvectorfilewriter.cpp
@@ -1982,10 +1982,10 @@ QgsVectorFileWriter::WriterError QgsVectorFileWriter::writeAsVectorFormat( QgsVe
     req.setFlags( QgsFeatureRequest::NoGeometry );
   }
   req.setSubsetOfAttributes( allAttr );
+  if ( onlySelected )
+    req.setFilterFids( layer->selectedFeaturesIds() );
   QgsFeatureIterator fit = layer->getFeatures( req );
 
-  const QgsFeatureIds& ids = layer->selectedFeaturesIds();
-
   //create symbol table if needed
   if ( writer->symbologyExport() != NoSymbology )
   {
@@ -2027,9 +2027,6 @@ QgsVectorFileWriter::WriterError QgsVectorFileWriter::writeAsVectorFormat( QgsVe
   // write all features
   while ( fit.nextFeature( fet ) )
   {
-    if ( onlySelected && !ids.contains( fet.id() ) )
-      continue;
-
     if ( shallTransform )
     {
       try