Using pg_upgrade with lolor

The pg_upgrade utility is used for upgrading Postgres versions.

You can use pg_upgrade with the lolor extension installed provided that you are using lolor version 1.2.2 or later. If you are using an older version of lolor, you will need to upgrade the extension first.

Both clusters must list lolor in shared_preload_libraries; without it the new cluster cannot load lolor's library, so restoring the extension fails.

Before running pg_upgrade, you must disable lolor. After executing pg_upgrade, you can enable lolor. Use psql or another client to disable lolor:

db1_17=# SELECT lolor.disable();

Next, execute the upgrade. A sample pg_ugrade command appears below:

# pg_upgrade --old-datadir=/data/db1_17 \
        --new-datadir=/data/db1_18 \
        --old-bindir=/usr/lib/postgresql/17/bin \
        --new-bindir=/usr/lib/postgresql/18/bin \
        --link

Then, use psql to enable lolor:

db1_18=# SELECT lolor.enable();

Reconnect any client sessions afterwards. lolor.enable() and lolor.disable() change which function OID owns each pg_catalog.lo_* name, and libpq resolves those OIDs once per connection and caches them for the life of the connection. A session that used a large object before the switch would otherwise keep calling the previous implementation.