Re: Allow round() function to accept float and double precision

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

From: Tom Lane <tgl@sss.pgh.pa.us>
To: Dean Rasheed <dean.a.rasheed@gmail.com>
Cc: David Rowley <dgrowleyml@gmail.com>, "David G. Johnston" <david.g.johnston@gmail.com>, Sayyid Ali Sajjad Rizavi <sasrizavi@gmail.com>, pgsql-hackers@lists.postgresql.org
Date: 2022-12-01T14:39:53Z
Lists: pgsql-hackers
Dean Rasheed <dean.a.rasheed@gmail.com> writes:
> I don't really see the point of such a function either.
> Casting to numeric(1000, n) will work fine in all cases AFAICS (1000
> being the maximum allowed precision in a numeric typemod, and somewhat
> more memorable).

Right, but I think what the OP wants is to not have to think about
whether the input is of exact or inexact type.  That's easily soluble
locally by making your own function:

create function round(float8, int) returns numeric
  as $$select pg_catalog.round($1::pg_catalog.numeric, $2)$$
  language sql strict immutable parallel safe;

but I'm not sure that the argument for it is strong enough to
justify putting it into Postgres.

> The fact that passing a negative scale to round() isn't documented
> does seem like an oversight though...

Agreed, will do something about that.

			regards, tom lane



Commits

  1. Doc: add example of round(v, s) with negative s.