ULong64_t size = sizeof(AliFlatESDEvent);
size += 2 * sizeof( AliFlatESDVertex );
+ // one Long64_t per track for tracks table
size += esd->GetNumberOfTracks() * ( AliFlatESDTrack::EstimateSize() + sizeof(Long64_t) );
size += AliESDRun::kNTriggerClasses * sizeof(AliFlatESDTrigger) ;
if( fillV0s ) size += esd->GetNumberOfV0s()*sizeof(AliFlatESDV0);