Re: Fw: Event formats

From: Christian Holm Christensen (cholm@hehi03.nbi.dk)
Date: Thu Mar 09 2000 - 20:01:06 EST

  • Next message: Christian Holm Christensen: "Event formats - again, and BrEventIO"

    Hi Flemming, et al, 
    
    On Thu, 9 Mar 2000 17:30:24 -0600 "Flemming Videbaek"
    <videbaek@sgs1.hirg.bnl.gov> wrote:
    
    > I think we should look carefully into what is really possible within
    > ROOT, and think that particular for the later stages of analysis
    > (following reconstruction) much could be gained by this. 
    > I also recollect that the major reason we use the (simple) tree for
    > output is that the serial output of the TObjArrays will not work
    > well with ROOT since it generates a key per events,- those are all
    > kept in memeory and the writting time increased dramatically with
    > number of eventts analysed. 
    
    I believe that STAR and BaBar actually is storing Event data directly
    in ROOT TTree's. That's anyway my impression form browsing the ROOT
    2000 pages (http://root.cern.ch/root/R2000Program.html), so I guess
    some of your concerns (valid as they are), may be taken care of. I
    know STAR has developed a way to securely upgrade classes. Again, take
    a look at the ROOT 2000 pages. 
    
    > If you look carefully you will notice that this is in fact commented
    > out. 
    
    Oh yeah, you're right, sorry. I was looking at the web pages, and the
    `/* */' pair was probaly too hard to see - sorry. 
     
    > When you deal with an EventNode one should be able to defined if a
    > 'subtree' is persistent for a given write and written to
    > disk. E.G. imagine an reconstruction pass that can generate many
    > kinds of objects TPC local tracking
    >  --- CLustere
    > --  HitClusters
    > --  DetectorHits
    > --  Local tracks
    > During the development and for selected analysis you might save all information to the outputfiles, while
    > later during routine production you would drop these. The reason for
    > doing it at the 'output' stage could be to have the information
    > avaliable for several modules. 
    > I do agree the commented code is not the right implementation, but
    > is not urgent at this point. 
    
    I don't get this. What does that have to do with the use of
    THashTable?
    
    > On the BrRawDataInput I think some of the issue is a matter of style
    > if methods are too large. Though I do not think one should spend
    > much time of fixing style in this area - if  it aint' broke don't
    > fixe it. 
    
    In part, I agree with you. However, to ease the reading (i.e.,
    understanding) for others than the one writting the code, good style
    is imperative. I'm afraid that I don't find these methods good style -
    sorry guys. 
    
    > The naming issue is relevant and we should fix it now. The naming is
    > meant to be the following For DataTables the name is
    > "<ClassName><space><DetectorName>" where the ClassName is omitting
    > the Br (try to a=evaluate how many Gb you save over a year that
    > way. It is unique in so far it describes the dataobjects in the
    > table.  
    
    Cool! 
    
    Oh, and for Konstantin: The code I repoduced in my previous mail, was
    `cut-and-paste' from the existing code in `BrRawDataInput', so I don't
    propose to check record numbers more often than is already done in the
    existing code. If I inadvertly copied too much, then I'm sorry for
    sending the wrong message.   
    
    Cheers, 
    
    Christian  -----------------------------------------------------------
    Holm Christensen                             Phone:  (+45) 35 35 96 91 
      Sankt Hansgade 23, 1. th.                  Office: (+45) 353  25 305 
      DK-2200 Copenhagen N                       Web:    www.nbi.dk/~cholm    
      Denmark                                    Email:       cholm@nbi.dk
    



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