Re: [HACKERS] Re: pgsql: Extract catalog info for error reporting before an error actually

Simon Riggs wrote:
> On Thu, 2007-10-25 at 13:51 -0400, Andrew Dunstan wrote:
>
>> Michael Paesold wrote:
>>
>>> In the previous discussion, Simon and me agreed that schema changes
>>> should not happen on a regular basis on production systems.
>>>
>>> Shouldn't we rather support the regular usage pattern instead of the
>>> uncommon one? Users doing a lot of schema changes are the ones who
>>> should have to work around issues, not those using a DBMS sanely. No?
>>>
>>>
>> Unfortunately, doing lots of schema changes is a very common phenomenon.
>> It makes me uncomfortable too, but saying that those who do it have to
>> work around issues isn't acceptable IMNSHO - it's far too widely done.
>>
>
> We didn't agree that DDL was uncommon, we agreed that running DDL was
> more important than running an auto VACUUM. DDL runs very quickly,
> unless blocked, though holds up everybody else. So you must run it at
> pre-planned windows. VACUUMs can run at any time, so a autoVACUUM
> shouldn't be allowed to prevent DDL from running. The queuing DDL makes
> other requests queue behind it, even ones that would normally have been
> able to execute at same time as the VACUUM.
>
> Anyway, we covered all this before. I started off saying we shouldn't do
> this and Heikki and Michael came up with convincing arguments, for me,
> so now I think we should allow autovacuums to be cancelled.
>
>

Perhaps I misunderstood, or have been mistunderstood :-) - I am actually
agreeing that autovac should not block DDL.

cheers

andrew