| From: | Greg Stark <stark(at)mit(dot)edu> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Peter Geoghegan <peter(at)2ndquadrant(dot)com>, Ants Aasma <ants(at)cybertec(dot)at>, Greg Smith <greg(at)2ndquadrant(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Patch: add timing of buffer I/O requests |
| Date: | 2012-04-25 17:58:36 |
| Message-ID: | CAM-w4HN2Yau2qz5GNpmG2oQvZxO+ioygjiObstXxeoeShDL=MA@mail.gmail.com |
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On Wed, Apr 25, 2012 at 5:47 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)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
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