Re: New vacuum option to do only freezing

On Wed, Jun 19, 2019 at 12:51:41PM -0700, Peter Geoghegan wrote:
> On Tue, Jun 18, 2019 at 10:39 PM Michael Paquier <michael@paquier.xyz> wrote:
>> +INSERT INTO no_index_cleanup(i, t) VALUES(1, repeat('1234567890',30000));
>> Do we really need a string as long as that?
> 
> Specifying EXTERNAL storage might make things easier. I have used
> PLAIN storage to test the 1/3 of a page restriction within nbtree, and
> to test a bug in amcheck that was related to TOAST compression.

Ah, good point here.  That makes sense.

>> It seems to me that we'd want tests to make sure that indexes are
>> actually cleaned up, where pageinspect could prove to be useful.
> 
> That definitely seems preferable, but it'll be a bit tricky to do it
> in a way that doesn't run into buildfarm issues due to alignment. I
> suggest an index on a text column to avoid problems.

I am not completely sure how tricky that may be, so I'll believe you
on this one :)

So, to keep things simple and if we want to get something into v12, I
would suggest to just stress more combinations even if the changes are
not entirely visible yet.  If we get a couple of queries to run with
the option disabled on the table, its toast or both by truncating and
filling in the table in-between, we may be able to catch some issues
by stressing those code paths.

And I finish with the attached.  Thoughts?
--
Michael