Why ODBMS ?
OO programming paradigm
- is the modern, industry direction
- supported by C++, Java high level languages
- excellent choice of both free and commercial class libraries
- suits our problem space well: rich hierarchy of complex data types (raw data, tracks, energy clusters, particles, missing energy, time-dependent calibration constants)
- Allows us to take full advantage of industry developments in software technology
Need to make some objects “persistent”
- raw data
- newly computed, useful, objects
Need an object store that supports an evolving data model and scales to many PetaBytes (1015 Bytes)
- (O)RDBMS wont work: For one year’s data would need a virtual table with 109 rows and many columns
Require persistent heterogeneous object location transparency, replication
- Multiple platforms, arrays of software versions, many applications, widely distributed in collaboration
- Need to banish huge “logbooks” of correspondences between event numbers, run numbers, event types, tag information, file names, tape numbers, site names etc.