Subject:
Re: storing a track to the database...
From:
john.baines@rl.ac.uk
Date:
Mon, 22 Oct 2001 17:00:58 +0100 (BST)
To:
David Adams <dladams@bnl.gov>

Hi David,


> I propose that the EDO contains indices specifying its list of
> parent EDO's. (This is consistent with the requirement that the list of
> parent EDO's be sufficient to recreate the child.) A PDO is restricted
> to referencing PDO's within these parents.


Thanks for the clarification. Let me check I understand. To take a
concrete example: say an inner detector track consists of SiTrackerClusters
and TRT straw information (let call these TrtHits). Now you say the
TrackCollection contains a list of identifiers for all the contributing
SiTrackerClusterCollections and TrtHitCollections. In general there
will be about 7 SiTrackerClusterCollections and I guess a similar
number of TrtHitCollections for each track. I understand that
you are proposing the individual tracks have a "reference" to
the contributing clusters, where this "reference" is something that
contains information identifying the relevant collection and the cluster
within that collection. Is this correct?


> I assume we agree that we want to impose the requirement that PDO's be
> able to point back the the PDO's used in their creation. For example a
> track carries a list of clusters from which it is created.


Well, my main point was that an alternative to the actual track objects
being burdened with a list of clusters would be for something external
to impliment the relationship between objects. I guess an alternative
to my suggestion of a DataHistoryService would be that the collection
impliments the association.

I guess I should admit I am thinking of this with a Level-2 trigger
bias. We would like to use the same objects as offline (at least PDO and
preferably EDO's as well), but we don't want these objects to get too heavy.

                 Cheers
                     John
-- \ John Baines email : j.t.m.baines@rl.ac.uk / \ Rutherford Appleton Laboratory, / \ Chilton, Didcot, Oxon. OX11 OER. UK / \ Phone : [+44] (0)1235 44 6377 (direct) / \ 6733 (Fax) / \ 82 1900 (switchboard)/