Dave Cramer <davecramer@gmail.com> writes:
> On Wed, 14 Jul 2021 at 15:09, David G. Johnston <david.g.johnston@gmail.com>
> wrote:
>> "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."
> This is still rather opaque. Without intimate knowledge of what changes
> have occurred in each extension I have installed; how would I know what I
> have to fix after the upgrade.
That's exactly why we don't force upgrades of extensions. It is on the
user's head to upgrade their extensions from time to time, but we don't
make them do it as part of pg_upgrade. (There are also some
implementation-level reasons to avoid this, IIRC, but the overall
choice is intentional.)
I agree this documentation could be worded better.
As a first step I propose the following
diff --git a/doc/src/sgml/ref/pgupgrade.sgml b/doc/src/sgml/ref/pgupgrade.sgml
index a83c63cd98..f747a4473a 100644
--- a/doc/src/sgml/ref/pgupgrade.sgml
+++ b/doc/src/sgml/ref/pgupgrade.sgml
@@ -305,9 +305,10 @@ make prefix=/usr/local/pgsql.new install
Install any custom shared object files (or DLLs) used by the old cluster
into the new cluster, e.g., <filename>pgcrypto.so</filename>,
whether they are from <filename>contrib</filename>
- or some other source. Do not install the schema definitions, e.g.,
- <command>CREATE EXTENSION pgcrypto</command>, because these will be upgraded
- from the old cluster.
+ or some other source. Do not execute CREATE EXTENSION on the new cluster.
+ The extensions will be upgraded from the old cluster. However it may be
+ necessary to recreate the extension on the new server after the upgrade
+ to ensure compatibility with the new library.
Also, any custom full text search files (dictionary, synonym,
thesaurus, stop words) must also be copied to the new cluster.
</para>
Another idea
is that possibly pg_upgrade could produce a list of extensions
that are not the latest version, so people know what's left to
be addressed.
It would be possible to look at the control files in the new cluster to see the default version and simply output a file with the differences.
We can query pg_extension for the currently installed versions.
Dave
