On Tue, Aug 09, 2011 at 09:41:00PM +0200, Florian Pflug wrote:
> Couldn't we simply give the user a way to specify, per column, whether or
> not that column is a "KEY" column? Creating a foreign key constraint could
> still implicitly mark all referenced columns as KEY columns, but columns
> would no longer be "KEY" columns simply because they're part of a UNIQUE
> constraint. Users would be free to add arbitrary columns to the set of
> "KEY" columns by doing ALTER TABLE ALTER COLUMN SET KEY.
What would be the use case for manually expanding the set of key columns?
If you have a heavily-updated table referenced by slowly-changing tables, it
might pay off to disable the optimization entirely. That would be an esoteric
escape hatch to provide for an uncommon use case, though.
--
Noah Misch http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
