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.
However it may be
+ necessary to recreate the extension on the new server after the upgrade
+ to ensure compatibility with the new library.
My uncertainty revolves around core extensions since it seems odd to tell the user to overwrite them with versions from an older version of PostgreSQL.
Ok. Just re-read the docs a third time…no uncertainty regarding contrib now…following the first part of the instructions means that before one could re-run create extension they would need to restore the original contrib library files to avoid the new extension code using the old library. So that whole part about recreation is inconsistent with the existing unchanged text.
The way I solved the original problem of having old function definitions for pg_stat_statement functions in the *new* library was by recreating the extension which presumably redefines the functions correctly.
I'm thinking at this point we need something a bit more sophisticated like
ALTER EXTENSION ... UPGRADE. And the extension knows how to upgrade itself.
