From: Bruce Momjian <bruce@momjian.us>
To: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
Cc: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Michael Paquier <michael@paquier.xyz>
Cc: Andres Freund <andres@anarazel.de>
Subject: Re: transction_timestamp() inside of procedures
Date: Tue, 2 Oct 2018 10:16:29 -0400
Message-ID: <20181002141629.GA22680@momjian.us> (raw)
In-Reply-To: <4ff8e6a2-c585-02fe-3f20-b9aa26fa2c4f@2ndquadrant.com>
References: <20180926155443.u4zh7jactzflys3z@alvherre.pgsql>
<ec816bd0-0357-23a9-bea2-3ef1619eb340@2ndquadrant.com>
<e2ad8aaf-e1d8-499e-4de0-e3616f8d908d@2ndquadrant.com>
<4ff8e6a2-c585-02fe-3f20-b9aa26fa2c4f@2ndquadrant.com>
On Tue, Oct 2, 2018 at 10:55:56AM +0200, Peter Eisentraut wrote:
> On 28/09/2018 09:35, Peter Eisentraut wrote:
> >> That's certainly a good argument. Note that if we implemented that the
> >> transaction timestamp is advanced inside procedures, that would also
> >> mean that the transaction timestamp as observed in pg_stat_activity
> >> would move during VACUUM, for example. That might or might not be
> >> desirable.
> >
> > Attached is a rough implementation.
> >
> > I'd be mildly in favor of doing this, but we have mentioned tradeoffs in
> > this thread.
>
> So do we want to do this or not?
I thought some more about this. I think there are a few issues:
1 Utility: since you can't use CALL in a transaction block, our
current code will always have transaction_timestamp() and
statement_timestamp() as identical in a procedure. Having
transaction_timestamp() advance on COMMIT gives users a new ability.
2 Surprise: What do people use transaction_timestamp() for and what
behavior would be most expected?
3 Other databases: How do other database systems handle this, and the
SQL standard?
Based on 1 and 2, I suggest we change transaction_timestamp() to advance
on COMMIT in procedure, and document this. I have no idea on #3.
--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ As you are, so once was I. As I am, so you will be. +
+ Ancient Roman grave inscription +
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-hackers@postgresql.org
Cc: bruce@momjian.us, peter.eisentraut@2ndquadrant.com, alvherre@2ndquadrant.com, tgl@sss.pgh.pa.us, michael@paquier.xyz, andres@anarazel.de
Subject: Re: transction_timestamp() inside of procedures
In-Reply-To: <20181002141629.GA22680@momjian.us>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox