> Hi Rene, > > > > > From the following line of ntCorr->Print(): > > > > *Entries : 8595694 : Total = 275456000 bytes File Size = > > 0 > > > > I conclude that you did: > > TTree *ntCorr = new TTree(... > > TFile *f = new TFile(... > > instead of > > TFile *f = new TFile(.. > > TTree *ntCorr = new TTree(.. > > > > In the first case, the Tree will be created in memory (275 MBytes!) > > In the second case, buffers (baskets) will be dumped to the file > > when full. > > The memory requirements will be less than 1 Mbyte. > > > > Yes, your conclusion is correct. ntCorr is an ntuple containging processed > data - I sometimes spin through this and it is quite fast (compared to the > input ntuple "nt".) I quite enjoy the benefit of having the entire 275 MB > in RAM! Is there a way to tell root "I have a lot of memory, if you can fit > the ntuple into RAM, please do" without simple building the ntuple w/out a > TFile > first? Hello Ed, If you want to keep everything in memory why do you want TTree then ? Just use the "normal" C++ object and save it out with TObject::Write method Cheers , Valeri
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