From: Bruce Momjian <pgman@candle.pha.pa.us>
Message-Id: <200209232041.g8NKfix19001@candle.pha.pa.us>
Subject: Re: [GENERAL] CURRENT_TIMESTAMP
In-Reply-To: <200209231336.59105.josh@agliodbs.com>
To: josh@agliodbs.com
Date: Mon, 23 Sep 2002 16:41:44 -0400 (EDT)
Cc: Manfred Koizar <mkoi-pg@aon.at>, Tom Lane <tgl@sss.pgh.pa.us>,
	Aaron Held <aaron@MetroNY.com>, Roberto Mello <rmello@cc.usu.edu>,
	Neil Conway <neilc@samurai.com>, pgsql-sql@postgresql.org
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Content-Type: text/plain; charset=US-ASCII

Josh Berkus wrote:
> I, for one, would judge that the start time of the statement is "during the 
> execution"; it would only NOT be "during the execution" if it was a value 
> *before* the start time of the statement.  It's a semantic argument.
> 
> The spec is, IMHO, rather vague on how this would relate to transactions.  I 
> do not find it at all inconsitent that Bruce, Thomas, and co. interpreted a 
> transaction to be an extension of an individual SQL statement for this 
> purpose (at least, that's what I guess they did).
> 
> Thus, if you accept the postulates that:
> 1) "During" a SQL statement includes the start time of the statement, and
> 2) A Transaction is the equivalent of a single SQL statement for many 
> purposes, 
> Then the current behavior is a logical conclusion.
> 
> Further, we could not change that behaviour without breaking many people's 
> applications.

I don't see how we can defend returning the start of the transaction as
the current_timestamp.  In a multi-statement transaction, that doesn't
seem very current to me.  I know there are some advantages to returning
the same value for all queries in a transaction, but is that value worth
returning such stale time information?

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