Обсуждение: autovacuum: use case for indenpedent TOAST table autovac settings

Hackers and PG users,

Does anyone see a need for having TOAST tables be individually
configurable for autovacuum?  I've finally come around to looking at
being able to use ALTER TABLE for autovacuum settings, and I'm wondering
if we need to support that case.

--
Alvaro Herrera                                http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.

Alvaro Herrera <alvherre@commandprompt.com> writes:
> Does anyone see a need for having TOAST tables be individually
> configurable for autovacuum?  I've finally come around to looking at
> being able to use ALTER TABLE for autovacuum settings, and I'm wondering
> if we need to support that case.

It seems like we'll want to do it somehow.  Perhaps the cleanest way is
to incorporate toast-table settings in the reloptions of the parent
table.  Otherwise dump/reload is gonna be a mess.

            regards, tom lane

Tom Lane wrote:
> Alvaro Herrera <alvherre@commandprompt.com> writes:
> > Does anyone see a need for having TOAST tables be individually
> > configurable for autovacuum?  I've finally come around to looking at
> > being able to use ALTER TABLE for autovacuum settings, and I'm wondering
> > if we need to support that case.
>
> It seems like we'll want to do it somehow.  Perhaps the cleanest way is
> to incorporate toast-table settings in the reloptions of the parent
> table.  Otherwise dump/reload is gonna be a mess.

Yeah, Magnus was suggesting this syntax:

ALTER TABLE foo SET toast_autovacuum_enable = false;
and the like.

My question is whether there is interest in actually having support for
this, or should we just inherit the settings from the main table.  My
gut feeling is that this may be needed in some cases, but perhaps I'm
overengineering the thing.

--
Alvaro Herrera                                http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support

Alvaro Herrera <alvherre@commandprompt.com> writes:
> Tom Lane wrote:
>> It seems like we'll want to do it somehow.  Perhaps the cleanest way is
>> to incorporate toast-table settings in the reloptions of the parent
>> table.  Otherwise dump/reload is gonna be a mess.

> My question is whether there is interest in actually having support for
> this, or should we just inherit the settings from the main table.  My
> gut feeling is that this may be needed in some cases, but perhaps I'm
> overengineering the thing.

It seems reasonable to inherit the parent's settings by default, in any
case.  So you could do that now and then extend the feature later if
there's real demand.

            regards, tom lane

On Wed, 2008-08-13 at 21:30 -0400, Tom Lane wrote:
> Alvaro Herrera <alvherre@commandprompt.com> writes:
> > Tom Lane wrote:
> >> It seems like we'll want to do it somehow.  Perhaps the cleanest way is
> >> to incorporate toast-table settings in the reloptions of the parent
> >> table.  Otherwise dump/reload is gonna be a mess.
>
> > My question is whether there is interest in actually having support for
> > this, or should we just inherit the settings from the main table.  My
> > gut feeling is that this may be needed in some cases, but perhaps I'm
> > overengineering the thing.
>
> It seems reasonable to inherit the parent's settings by default, in any
> case.  So you could do that now and then extend the feature later if
> there's real demand.

Yeh, I can't really see a reason why you'd want to treat toast tables
differently with regard to autovacuuming. It's one more setting to get
wrong, so no thanks.

--
 Simon Riggs           www.2ndQuadrant.com
 PostgreSQL Training, Services and Support