Re: Patch: add timing of buffer I/O requests - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Patch: add timing of buffer I/O requests
Date
Msg-id 7950.1335372448@sss.pgh.pa.us
Whole thread Raw
In response to Re: Patch: add timing of buffer I/O requests  (Robert Haas <robertmhaas@gmail.com>)
Responses Re: Patch: add timing of buffer I/O requests  (Robert Haas <robertmhaas@gmail.com>)
Re: Patch: add timing of buffer I/O requests  (Greg Stark <stark@mit.edu>)
List pgsql-hackers
Robert Haas <robertmhaas@gmail.com> writes:
> On Sat, Apr 14, 2012 at 10:33 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> 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.

Well, how about "the code is going to be quite a lot less readable"?
C can manipulate floats natively, but not numerics.

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.

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

Agreed, this has got to be pushed forward.
        regards, tom lane


pgsql-hackers by date:

Previous
From: Tom Lane
Date:
Subject: Re: remove dead ports?
Next
From: Robert Haas
Date:
Subject: Re: Temporary tables under hot standby