[Babase] ranker again

Susan Alberts alberts at duke.edu
Fri Oct 6 12:53:39 EDT 2006


See comments below:

>
> Master-slave (or consistency) relationships among rankings could
> in general form a directed acyclic graph. In other words, it is  
> plausible
> (though it doesn't come up in our case) for one ranking to have two
> masters (and vice versa). We could invent another "ranking  
> consistency"
> table to capture such relationships, but given that we have only a  
> very
> small number of ranking types, I'd vote for just a handful of triggers
> (probably 4 is enough) to enforce consistency, instead of complicating
> the schema further.

I agree with the points made in this paragraph.
>
>> The other question to consider is intervals over which ranks
>> are computed/in-effect.  If rankings are always month-by-month
>> then this is not an issue.  At the moment all the validation
>> code assumes that the ranks that are saved are computed based
>> on group membership that occurs during a single month --
>> the check that says you've got to be in the group (or
>> supergroup) during the month in order to be ranked.
>
> Yes, currently membership in a ranking is completed dictated by
> the definition query associated with the rank type for a given month.
> If we allow arbitrary ranking periods, the notion of consistency
> become not as well-defined.

We are very unlikely to ever rank over a period smaller than one  
month, and our current system allows us to rank over a period longer  
than one month although we don't store these (and probably will not  
want to). I think we are fine with a system that depends on ranks  
being specified for a given month.

Susan

-----------------------------------------------
Susan Alberts, Dept. Biology, Duke University, Durham NC 27708. Phone  
919-660-7272, Fax 919-660-7293. alberts at duke.edu





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