[BioSQL-l] UK definition for seqfeature

[Hilmar Lapp]

There is currently a compound unique key defined on seqfeature 
comprising of (bioentry_id,type_term_id,source_term_id,rank).

A while ago all but the first were nullable columns with the previously 
known problems of different behaviour between RDBMSs. The situation is 
much clearer defined now, as only source_term_id is left as nullable.

Can anyone name reasons why we should leave this column nullable? I.e., 
can people think of sensible use cases where you would not have a 
source_tag for a feature?

I believe even in GFF source is mandatory ...

	-hilmar

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Hilmar Lapp                            email: lapp at gnf.org
GNF, San Diego, Ca. 92121              phone: +1-858-812-1757
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