Re: CHECK constraints and optimizations

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>
To: Martijn van Oosterhout <kleptog@svana.org>
Cc: "scott.marlowe" <scott.marlowe@ihs.com>, Edmund Dengler <edmundd@eSentire.com>, pgsql-general@postgresql.org
Date: 2004-05-07T01:02:21Z
Lists: pgsql-general
Martijn van Oosterhout <kleptog@svana.org> writes:
> I can't see why this wouldn't work.

Doubtless you could do it.  The problem with the idea is that those
inference tests are pretty expensive.  I think that any such thing would
waste significant numbers of cycles on ordinary queries while only being
a win on a few poorly-written queries.

We do have to make a tradeoff between planning time and execution time,
and I fear that this idea is not going to be a win in those terms.
If you feel like experimenting, though, go for it ...

			regards, tom lane