Re: REINDEX backend filtering

On Mon, Mar 15, 2021 at 10:13:55AM -0700, Mark Dilger wrote:
>
>
> > On Mar 15, 2021, at 9:52 AM, Julien Rouhaud <rjuju123(at)gmail(dot)com> wrote:
> >
> > But there are also the tests in collate.icu.utf8.out which will fake outdated
> > collations (that's the original tests for the collation tracking patches) and
> > then check that outdated indexes are reindexed with both REINDEX and REINDEX
> > (OUDATED).
> >
> > So I think that all cases are covered. Do you want to have more test cases?
>
> I thought that just checked cases where a bogus 'not a version' was put into pg_catalog.pg_depend. I'm talking about having a collation provider who returns a different version string and has genuinely different collation rules between versions, thereby breaking the index until it is updated. Is that being tested?

No, we're only checking that the infrastructure works as intended.

Are you saying that you want to implement a simplistic collation provider with
"tunable" ordering, so that you can actually check that an ordering change will
be detected as a corrupted index, as in you'll get some error or incorrect
results?

I don't think that this infrastructure is the right place to do that, and I'm
not sure what would be the benefit here. If a library was updated, the
underlying indexes may or may not be corrupted, and we only warn about the
discrepancy with a low overhead.