Re: Primary Keys and Foreign Keys

Jan Hidders <hidders_at_REMOVE.THIS.win.tue.nl> wrote in message news:903d4e$5db$1_at_news.tue.nl...

Followup to the followup: I've looked pretty hard but have been unable to find
clear guidance for indexing on many-many tables. This actually applies more generally to composite indexes:

Say I have a many-many table with the primary/candidate key being a composite of the two foreign keys. The database is going to create an index on these two fields. Now say that standard select queries will be one field or the other. Do I need to define two additional indices -- one for each of the two foreign keys?

In other words, does a database index on a composite key provide assistance to select statements on a subset of these keys?

So fundamental. And yet, its so fundamental I've never seen it addressed :-/ Received on Thu Nov 30 2000 - 00:50:18 CET