Re: Patch: add timing of buffer I/O requests

On Sat, Apr 14, 2012 at 10:33 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> The internal representation doesn't have to be (and certainly
>> shouldn't be) numeric.  But if you translate to numeric before
>> returning the data to the user, then you have the freedom, in the
>> future, to whack around the internal representation however you like,
>> without breaking backward compatibility.  Choosing float8 for the
>> external representation is fine as long as we're sure we're not ever
>> going to want more than 16 significant digits, but I see no particular
>> value in baking in that assumption.  But perhaps, as the saying goes,
>> 16 digits ought to be enough for anyone.
>
> There's no particular reason to think that Moore's Law is going to
> result in an increase in the fractional precision of timing data.
> It hasn't done so in the past, for sure.

Perhaps, but nobody's explained what we gain out of NOT using numeric.
"It's slow" doesn't impress me; selecting from a system view doesn't
need to be lightning-fast.

However, the main thing here is that we need to do *something* here...

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