Re: [HACKERS] Sum aggregate calculation for single precsion real

On Tue, Feb 14, 2017 at 11:45 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> You could perhaps make an argument that sum(float4) would have less risk
> of overflow if it accumulated in and returned float8, but frankly that
> seems a bit thin.

I think that's more or less the argument Konstantin is in fact making.
Whether it's a good argument or a thin one is a value judgement.
Personally, I find it somewhere in the middle: I think the way it
works now is reasonable, and I think what he wants would have been
reasonable as well.  However, I find it hard to believe it would be
worth changing now on backward compatibility grounds.  He doesn't like
the way it works currently, but we have no way of knowing how many
people who are happy with the way it works today would become unhappy
if we changed it.  We need a fairly compelling reason to risk breaking
somebody's SQL, and I don't think this rises to that level.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company