Re: Reducing the overhead of NUMERIC data

On Wed, Nov 02, 2005 at 06:12:37PM -0500, Tom Lane wrote:
> Simon Riggs <simon@2ndquadrant.com> writes:
> > It seems straightforward enough to put in an additional test, similar to
> > the ones already there so that if its too big for a decimal we make it a
> > float straight away - only a float can be that big in that case. After
> > that I can't really see what the problem is?
>
> Wrong answer.  You'll be introducing weird corner cases into the type
> resolution behavior.
>
> An approach that would actually have some credibility would be to not
> resolve constants to NUMERIC right away, but to invent an UNKNOWNNUMERIC
> pseudotype with coercion behavior comparable to the existing UNKNOWN
> type for string literals.  This has been proposed before but hasn't
> really been needed so far.  Of course, this converts the project from a
> minor localized hack on NUMERIC into a major piece of fiddling with the
> type resolution rules, with the potential for unforeseen side-effects on
> the behavior of other data types.  It might be worth doing anyway --- I
> don't recall at the moment what problems UNKNOWNNUMERIC was intended to
> solve, but if they're still open issues then it's something we ought to
> get around to sometime.

Thought I'd look to see if I could find anything about UNKNOWNNUMERIC,
but no such luck (ISTM we really need a better way to find discussion on
old ideas...) But while looking I did find this TODO, which might be
relevant to the current discussion:

# Change NUMERIC to enforce the maximum precision, and increase it

Unfortunately I can't find any reference to that in the archives...
--
Jim C. Nasby, Sr. Engineering Consultant      jnasby@pervasive.com
Pervasive Software      http://pervasive.com    work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf       cell: 512-569-9461