Re: [ROOT] TChain::Merge problems in 3.03/7?

From: Rene Brun (Rene.Brun@cern.ch)
Date: Fri Sep 06 2002 - 11:14:51 MEST


Hi Bram,

There is no limitation on the number of files in TChain::Merge.
Could you make one single tar file with your 40 files and let me know
where I can access it?

Rene Brun

On Wed, 4 Sep 2002, Bram Wijngaarden wrote:

> 
> Hi,
> 
> Some strange behaviour showed op trying to merge a flat ntuple in root
> 3.03/7 (compiled for sgiegcs). I'm trying to merge TNtuples from 40 files.
> The final (merged) ntuple has too few entries - about 1700. When I just
> merge a subset of 10 of these files the final number of entries is much
> larger, about 14k, which makes more sense. This is fully reproducable. The
> size of the target files is about 35k for the 1700 entries and 224k for
> the 10 files (the size of the source files is about 350kb each which
> includes a ton of histograms, so the total tally is well below the default
> fgMaxTreeSize of 1.9 Gb).
> 
> Just adding a subset of 1, 2, 3 etc files seems to go fine - at an
> increment of about 30kb per file - until I have 15 files merged, for a
> file size of 505906 bytes. 16 files give me 505929 bytes. 17 files give me
> 505906 again, and so do 18 files. 19 files give me 505917, and then 505906
> comes back. This sort of behaviour goes on ad infinitum.
> 
> Is there a problem with TChain handling a certain number of files? Is
> there a problem with the file size? I'm totally stumped.
> 
> Cheers,
> Bram
> 
> -
> D.A. Wijngaarden	Meijhorst 6422
> AiO KUN-EHEF		6537 LE Nijmegen
> Experiment: D0		The Netherlands
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> "Fuimus" - Robert the Bruce
> 
> 



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