Re: [BUGS] numerics lose scale and precision in views of unions

On Wed, Aug 09, 2006 at 11:35:48PM -0400, Tom Lane wrote:
> Stephen Frost <sfrost(at)snowman(dot)net> writes:
> > * Tom Lane (tgl(at)sss(dot)pgh(dot)pa(dot)us) wrote:
> >> Yeah, because numeric_cmp says that 1.0 and 1.00 are equal (what else
> >> could it say? "less" and "greater" are surely wrong). So you need to
> > It could say "not equal" pretty reasonably as the scale is
> > different.
> Nope, there are exactly three options: equal, less, greater.
> btree doesn't understand anything else.

Mathematically, 1.0 = 0.9500... -> 1.05000...

In theory, B-Tree could be fine with this. As long as the operators
for =, <>, <, and > are made to consistently understand this principle.
For example:

1.0 = 0.95
1.0 = 1.05
1.0 <> 0.94
1.0 <> 1.06
0.94 < 1.0
1.06 > 1.0

I'm not sure that it warrants being changed, though. Storing mixed
precision values in a column and expecting the database to understand
rounding rules does not appeal to me. Too magical.

Cheers,
mark

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