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

Greg Stark <stark@mit.edu>

From: Greg Stark <stark@mit.edu>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Robert Haas <robertmhaas@gmail.com>, Peter Geoghegan <peter@2ndquadrant.com>, Ants Aasma <ants@cybertec.at>, Greg Smith <greg@2ndquadrant.com>, pgsql-hackers@postgresql.org
Date: 2012-04-25T17:58:36Z
Lists: pgsql-hackers
On Wed, Apr 25, 2012 at 5:47 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Also, as was pointed out upthread, the underlying data in shared memory
> is almost certainly never going to be infinite-precision; so using
> numeric in the API seems to me to be more likely to convey a false
> impression of exactness than to do anything useful.

I don't think that follows. The underlyng data will be measured in
some metric unit of time like microsecond or nanosecond or something
like that. So a base-10 representation will show exactly the precision
that the underlying data has. On the other hand a floating point
number will show a base-2 approximation that may in fact display with
more digits than the underlying data representation has.

-- 
greg