> Sergei > > Maria pointed out that if we already have amp and fovid columns, > then we can build a composite key and given that it is unique, > it can be easily used as the primary key for that table,
I understand that anything unique and not null can be made a primary key. But is there a reason to prefer (fovid+amp) over id, as the primary key? > which means that we do not need the id at all. Not sure this is true: id is used to trace the lineage of sources: each source "knows" the id of the AmpImage it came from. Yes, one could also create a foreign key to reference (fovid+amp) for that purpose, but is this better? Sergei. _______________________________________________ LSST-data mailing list [email protected] http://www.lsstmail.org/mailman/listinfo/lsst-data
