Re: numeric/decimal docs bug?

Bruce Momjian wrote:
> Jan Wieck wrote:
> >
> > I missed some of the discussion, because I considered the
> > 1,000 digits already beeing complete nonsense and dropped the
> > thread. So could someone please enlighten me what the real
> > reason for increasing our precision is? AFAIR it had
> > something to do with the docs. If it's just because the docs
> > and the code aren't in sync, I'd vote for changing the docs.
>
> I have done a little more research on this. If you create a numeric
> with no precision:
>
> CREATE TABLE test (x numeric);
>
> You can insert numerics that are greater in length that 1000 digits:
>
> INSERT INTO test values ('1111(continues 1010 times)');
>
> You can even do computations on it:
>
> SELECT x+1 FROM test;
>
> 1000 is pretty arbitrary. If we can handle 1000, I can't see how larger
> values somehow could fail.

And I can't see what more than 1,000 digits would be good
for. Bruce, your research is neat, but IMHO wasted time.

Why do we need to change it now? Is the more important issue
(doing the internal storage representation in base 10,000,
done yet? If not, we can open up for unlimited precision at
that time.

Please, adjust the docs for now, drop the issue and let's do
something useful.

> Also, the numeric regression tests takes much longer than the other
> tests. I don't see why a test of that length is required, compared to
> the other tests. Probably time to pair it back a little.

What exactly do you mean with "pair it back"? Shrinking the
precision of the test or reducing it's coverage of
functionality?

For the former, it only uses 10 of the possible 1,000 digits
after the decimal point. Run the numeric_big test (which
uses 800) at least once and you'll see what kind of
difference precision makes.

And on functionality, it is absolutely insufficient for
numerical functionality that has possible carry, rounding
etc. issues, to check a function just for one single known
value, and if it computes that result correctly, consider it
OK for everything.

I thought the actual test is sloppy already ... but it's
still too much for you ... hmmmm.

Jan

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