Re: Fwd: Re: [PERFORM] Performance analysis of plpgsql code

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: "Karl O(dot) Pinc" <kop(at)meme(dot)com>
Cc: pgsql-patches(at)postgresql(dot)org
Subject: Re: Fwd: Re: [PERFORM] Performance analysis of plpgsql code
Date: 2005-06-29 01:53:28
Message-ID: 200506290153.j5T1rSr26346@candle.pha.pa.us
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Patch applied. Thanks. Your documentation changes can be viewed in
five minutes using links on the developer's page,
http://www.postgresql.org/developer/testing.

---------------------------------------------------------------------------

Karl O. Pinc wrote:
>
> On 06/27/2005 10:03:06 PM, Karl O. Pinc wrote:
>
> On 06/27/2005 08:34:19 PM, Michael Fuhr wrote:
> > On Tue, Jun 28, 2005 at 01:54:08AM +0000, Karl O. Pinc wrote:
> > > On 06/27/2005 06:33:03 PM, Michael Fuhr wrote:
> > >
> > > >See timeofday().
> > >
> > > That only gives you the time at the start of the transaction,
> > > so you get no indication of how long anything in the
> > > transaction takes.
> >
> > Did you read the documentation or try it? Perhaps you're thinking
> > of now(), current_timestamp, and friends, which don't advance during
> > a transaction; but as the documentation states, "timeofday() returns
> > the wall-clock time and does advance during transactions."
>
> Very sorry. I did not read through the complete documentation.
>
> > I just ran tests on versions of PostgreSQL going back to 7.2.8 and
> > in all of them timeofday() advanced during a transaction.
>
> For all your work a documentation patch is appended that
> I think is easier to read and might avoid this problem
> in the future. If you don't read all the way through the
> current cvs version then you might think, as I did,
> that timeofday() is a CURRENT_TIMESTAMP related function.
>
> Sorry, but 3 lines wrap in the patch
> in my email client. :(
>
>
> Karl <kop(at)meme(dot)com>
> Free Software: "You don't pay back, you pay forward."
> -- Robert A. Heinlein
>
>
> --- func.sgml 2005-06-26 17:05:35.000000000 -0500
> +++ func.sgml.new 2005-06-27 21:51:05.301097896 -0500
> @@ -5787,15 +5787,6 @@
> </para>
>
> <para>
> - There is also the function <function>timeofday()</function>, which
> for historical
> - reasons returns a <type>text</type> string rather than a
> <type>timestamp</type> value:
> -<screen>
> -SELECT timeofday();
> -<lineannotation>Result: </lineannotation><computeroutput>Sat Feb 17
> 19:07:32.000126 2001 EST</computeroutput>
> -</screen>
> - </para>
> -
> - <para>
> It is important to know that
> <function>CURRENT_TIMESTAMP</function> and related functions
> return
> the start time of the current transaction; their values do not
> @@ -5803,8 +5794,7 @@
> the intent is to allow a single transaction to have a consistent
> notion of the <quote>current</quote> time, so that multiple
> modifications within the same transaction bear the same
> - time stamp. <function>timeofday()</function>
> - returns the wall-clock time and does advance during transactions.
> + time stamp.
> </para>
>
> <note>
> @@ -5815,6 +5805,18 @@
> </note>
>
> <para>
> + There is also the function <function>timeofday()</function> which
> + returns the wall-clock time and advances during transactions. For
> + historical reasons <function>timeofday()</function> returns a
> + <type>text</type> string rather than a <type>timestamp</type>
> + value:
> +<screen>
> +SELECT timeofday();
> +<lineannotation>Result: </lineannotation><computeroutput>Sat Feb 17
> 19:07:32.000126 2001 EST</computeroutput>
> +</screen>
> + </para>
> +
> + <para>
> All the date/time data types also accept the special literal value
> <literal>now</literal> to specify the current date and time.
> Thus,
> the following three all return the same result:
>
>
> ---------------------------(end of broadcast)---------------------------
> TIP 4: Don't 'kill -9' the postmaster
>
>
> Karl <kop(at)meme(dot)com>
> Free Software: "You don't pay back, you pay forward."
> -- Robert A. Heinlein
>
>
> ---------------------------(end of broadcast)---------------------------
> TIP 7: don't forget to increase your free space map settings
>

--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073

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