Re: pg_upgrade does not upgrade pg_stat_statements properly

On Wed, Jul 14, 2021 at 11:59 AM Dave Cramer <davecramer@gmail.com> wrote:

On Wed, 14 Jul 2021 at 14:47, David G. Johnston <david.g.johnston@gmail.com> wrote:

On Wednesday, July 14, 2021, Dave Cramer <davecramer@gmail.com> wrote:

Notice the upgraded version is 1.5 and the new version is 1.8

I would think somewhere in the upgrade of the schema there should have been a create extension pg_stat_statements ?

That would be a faulty assumption.  Modules do not get upgraded during a server version upgrade.  This is a good thing, IMO.

This is from the documentation of pg_upgrade

Install any custom shared object files (or DLLs) used by the old cluster into the new cluster, e.g., pgcrypto.so, whether they are from contrib or some other source. Do not install the schema definitions, e.g., CREATE EXTENSION pgcrypto, because these will be upgraded from the old cluster. Also, any custom full text search files (dictionary, synonym, thesaurus, stop words) must also be copied to the new cluster.

If indeed modules do not get upgraded then the above is confusing at best, and misleading at worst.

"Install ... files used by the old cluster" (which must be binary compatible with the new cluster as noted elsewhere on that page) supports the claim that it is the old cluster's version that is going to result.  But I agree that saying "because these will be upgraded from the old cluster" is poorly worded and should be fixed to be more precise here.

Something like, "... because the installed extensions will be copied from the old cluster during the upgrade."

David J.