Hi, I am trying to implement versioning of a structure of interconnected objects so that I can see how the content looked at some point of time.
Probably I would need to use a temporal database with effective_from/ effective_to timestamps telling the time period when the information held in the record was true: http://martinfowler.com/ap2/timeNarrative.html If I had a flat object structure, I would simply pass a filter on the query: session.query(Object).filter(Object.effective_from >= time & time < Object.effective_to) However, in my schema, the Object has related entities which is also temporal data. The mapped relations ideally should have the 'time' parameter embedded in the ON part of JOIN clause. I know that I can declare all relations as lazy='dynamic' and always pass 'time'. But I would then lost the possibility to eagerly load data. It would be inefficient to retrieve a record set and for each record issue another queries to get values of temporal properties ( http://martinfowler.com/eaaDev/TemporalProperty.html ) What I am looking for is a parameter, which value is specified once during a query, that could be used in mapper declarations. Attribute loaders would then use that parameter automatically. Is this possible in SQLAlchemy? Regards, Adam -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
