On Sat, Jun 24, 2017 at 09:19:10AM +0530, Amit Kapila wrote:
> > I successfully upgraded last night from 9.2 to 9.4 and find other issue :-)
> >
> > It is about hash index and promote:
> > 1. create master
> > 2. create standby from it
> > 3. create unlogged table and hash index like:
> >  create unlogged table test (id int primary key, v text);
> >  create index on test using hash (id);
> > 3. stop master
> > 4. promote standby
> >
> > now, if you try to upgrade this new promoted master pg_upgrade will stop
> > on this hash index:
> > error while creating link for relation "public.test_id_idx" 
> > ("s/9.2/base/16384/16393" to "m/9.4/base/16422/16393"): No such file or 
> > directory
> > Failure, exiting
> >
> I am not sure if this is a problem because in the version you are
> trying hash indexes are not WAL-logged and the creation of same will
> not be replicated on standby, so the error seems to be expected.

Well, it certainly should not error out like this.  I have not seen such
a failure report before.

I think the fundamental problem is that unlogged objects
(pg_class.relpersistence='u') creates a file on the master, but doesn't
create anything on the standby since it is never transmitted over the
WAL (assuming the object is created after the base backup).

I assume the standby creates them as empty when it is promoted to
primary and someone tries to access the object.  I wonder if I need to
add a boolean to each object to record if it is unlogged, and allow
copy/link to silently fail in such cases.  Does that make sense?

  Bruce Momjian  <br...@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

+ As you are, so once was I.  As I am, so you will be. +
+                      Ancient Roman grave inscription +

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