Re: recovering from "found xmin ... from before relfrozenxid ..."

On Wed, Sep 16, 2020 at 10:40 AM Ashutosh Sharma <ashu(dot)coek88(at)gmail(dot)com> wrote:
>
> On Wed, Sep 16, 2020 at 9:14 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> >
> > Ashutosh Sharma <ashu(dot)coek88(at)gmail(dot)com> writes:
> > > On Wed, Sep 16, 2020 at 1:25 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> > >> * Should any of the other tables in the test be converted to temp?
> >
> > > Are you trying to say that we can achieve the things being done in
> > > test-case 1 and 2 by having a single temp table and we should aim for
> > > it because it will make the test-case more efficient and easy to
> > > maintain?
> >
> > Well, I'm just looking at the comment that says the reason for the
> > begin/rollback structure is to keep autovacuum's hands off the table.
> > In most if not all of the other places where we need that, the preferred
> > method is to make the table temp or mark it with (autovacuum = off).
> > While this way isn't wrong exactly, nor inefficient, it does seem
> > a little restrictive. For instance, you can't easily test cases that
> > involve intentional errors.
> >
> > Another point is that we have a few optimizations that apply to tables
> > created in the current transaction. I'm not sure whether any of them
> > would fire in this test case, but if they do (now or in the future)
> > that might mean you aren't testing the usual scenario for use of
> > pg_surgery, which is surely not going to be a new-in-transaction
> > table. (That might be an argument for preferring autovacuum = off
> > over a temp table, too.)
> >
>
> I agree with you on both the above points. I'll try to make the
> necessary changes to address all your comments. Also, I'd prefer
> creating a normal heap table with autovacuum = off over the temp table
> for the reasons you mentioned in the second point.
>

Attached is the patch with the changes suggested here. I've tried to
use a normal heap table with (autovacuum = off) wherever possible.
Please have a look and let me know for any other issues.

Thanks,

--
With Regards,
Ashutosh Sharma
EnterpriseDB:http://www.enterprisedb.com