Root Trees and Relational Databases

ROOT
1

Hi,

I am trying to set up a system to create a relational database layer that sits on top of a collection of TTrees. THe relational database will keep track of all events generated in my experiment and generate a unique event identifier for each event. If I desire to load particular event data for a particular event ID, I can query the relational database, which will tell me which TTree structure stores the data I desire.

Has anyone implmented a system providing the described features. If not, do you know whether this can be done within root itself - for example using a ttree structure to keep track of the relational information.

Do I need an object database for this?

Any information would be greatly appreciated.

If I have not been clear about the requirements of this project, I can provide more information.

Thank you.

Best Regards,

Jon Lederman
XENON Experiment (Nevis Laboratories)

2

Hello Jon,

there is a working example in the ROOT tutorials which does exactly what you want.
Look at the files sqlcreatedb.C sqlfilldb.C sqlselect.C .

Cheers,
Oliver

3

thanks, actually i was wondering whether anyone had experience interfacng root to an object database such as objectivity…

4

Note that in addition to the current SQL interfaces visible in the tutorials,we are working on a high level interface (class TTreeSQL)
that will allow to:
-view an existing SQL table as it was a ROOT TTree
-create a SQL table from a TTree
Delivery is expected with the June release
Concerning Objectivity, I suggest to go to Google and type
"root objectivity"

As you are probably aware the interest for Objectivity has gradually vanished to 0 and we are not planning to support this interface in thefuture.

Rene