Re: The vacuum-ignore-vacuum patch

Alvaro Herrera <alvherre@commandprompt.com> writes:
> Tom Lane wrote:
>> But the patch changes things so that *everyone* excludes the vacuum from
>> their xmin.  Or at least I thought that was the plan.

> We shouldn't do that, because that Xmin is also used to truncate
> SUBTRANS.

Yeah, but you were going to change that, no?  Truncating SUBTRANS will
need to include the vacuum xact's xmin, but we don't need it for any
other purpose.

> but it means
> lazy vacuum will never be able to use subtransactions.

This patch already depends on the assumption that lazy vacuum will never
do any transactional updates, so I don't see what it would need
subtransactions for.
        regards, tom lane