Re: ALTER TABLE ... ALTER COLUMN ... SET DISTINCT

On Mon, Apr 6, 2009 at 10:49 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Robert Haas <robertmhaas@gmail.com> writes:
>> Well, I think I was pretty clear about what I was trying to
>> accomplish.  I think there are more people who care about pg_dump
>> output being diffable than there are who need to set ndistinct more
>> accurately than 1 ppm and yet not as an integer.
>
> My, you *are* paranoid about float4 aren't you?

Yes - perhaps unreasonably so.  I've had so many bad experiences with
floating-point arithmetic that I've stopped trying to understand all
of the crazy things that can happen and started just avoiding it like
the plague.  Long live numeric!

> Once you've stored
> a given value, it's always going to dump the same.  Diffing different
> dumps isn't going to be a problem.  I concede that it might look
> different from what you put in originally, but we make no effort to
> guarantee that for DDL anyway.
>
> (It is true that with pg_dump's default float_extra_digits setting,
> outputs from this column might look uglier than they need to.
> I don't see anything wrong with having pg_dump forcibly round the
> value to five or so digits, though.)

So based on this comment and Stephen's remarks, I'm going to assume
that I'm succumbing to a fit of unjustified paranoia and re-implement
as you suggest.

...Robert