I have completed the open issues (that I'm aware of) for operator
exclusion constraints:
http://archives.postgresql.org/message-id/1257101600.27737.159.camel@jdavis
I'd now like to propose an extension to that feature: cardinality
limits.
It could go something like this (syntax still open for discussion, for
illustration only):
EXCLUSION (room CHECK WITH =, attendee CHECK WITH =, during CHECK WITH &&) CARDINALITY
30
To mean that at most 30 attendees can be signed up for the same room at
overlapping times.
I have hacked up a basic prototype just to make sure the semantics can
work reasonably well. I haven't implemented the syntax or catalog
changes yet, but the basic semantics with a hard-coded cardinality seem
to hold up.
Thoughts?
Regards,Jeff Davis
