Hello Rooters I noticed a pecularity when I tried to make use of the TTree::SetBranchStatus() method to deactivate most of the branches while reading a fairly complex tree from file. The tree is completely split and contains many TClonesArrays (>20). As already posted to this list some time ago, I too observed that reading events with ALL branches deactivated in the said way, is slower by almost a factor 10 than reading with all branches on. And that's certainly not what I hoped for! Now, snooping a bit through the relevant Root code I realized that while the flag set by TTree::SetBranchStatus(), namely kDoNotProcess, is tested in both TBranch::Fill() and TBranch::GetEntry(), it is NOT taken into account at all in TBranchElement::GetEntry(). Is this on purpose or simply an omission? If this is on purpose, then what should I do to speed up my tree input? I am using Root 3.03/09 on Debian linux. Romain Holzmann GSI, Darmstadt R.Holzmann@gsi.de
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