fixed bug with filter/grouping interaction (#4399)

Author: aalkin

Analysis/Tutorials/src/associatedExample.cxx

@@ -74,7 +74,8 @@ struct BTask {
 
 struct TTask {
   using myCol = soa::Join<aod::Collisions, aod::CollisionsExtra>;
-  void process(soa::Join<aod::Collisions, aod::CollisionsExtra>::iterator const& col, aod::Tracks const& tracks)
+  expressions::Filter multfilter = aod::collision::mult > 10;
+  void process(soa::Filtered<soa::Join<aod::Collisions, aod::CollisionsExtra>>::iterator const& col, aod::Tracks const& tracks)
   {
     LOGF(INFO, "[direct] ID: %d; %d == %d", col.globalIndex(), col.mult(), tracks.size());
     if (tracks.size() > 0) {

Framework/Core/include/Framework/AnalysisTask.h

@@ -240,7 +240,7 @@ struct AnalysisDataProcessorBuilder {
           if (hasIndexTo<std::decay_t<G>>(typename xt::persistent_columns_t{})) {
             auto result = o2::framework::sliceByColumn(indexColumnName.c_str(),
                                                        x.asArrowTable(),
-                                                       static_cast<int32_t>(gt.size()),
+                                                       static_cast<int32_t>(gt.tableSize()),
                                                        &groups[index],
                                                        &offsets[index]);
             if (result.ok() == false) {