Fermilab Computing Division

CS Document 2993-v0

ROOT: Support For Significant Evolutions of the User Data Model

Document #:
CS-doc-2993-v0
Document type:
Presentation
Submitted by:
Philippe Canal
Updated by:
Philippe Canal
Document Created:
12 Nov 2008, 13:02
Contents Revised:
12 Nov 2008, 13:02
Metadata Revised:
12 Nov 2008, 17:35
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Abstract:
One of the main strength of ROOT I/O is its inherent support for schema evolution. Two distinct modes are supported, one manual via a hand coded Streamer function and one fully automatic via the ROOT StreamerInfo. One draw back of the Streamer function is that they are not usable by TTrees in split mode. Until now, the automatic schema evolution mechanism could not be customized by the user and the only mechanism to go beyond the default rules was to revert to using the Streamer Function. In ROOT 5.22/00, we introduced a new mechanism which allows user extensions of the automatic schema evolution that can be used in object-wise, member-wise and split modes. This presentation will describe the myriads of possibility ranging from the simple assignment of transient members to the complex reorganization of the user's object model.
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Associated with Events:
CHEP 2009 held from 21 Mar 2009 to 27 Mar 2009 in Prague, Czech Republic
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