About pg_upgrade v15

The pg_upgrade executable is distributed with EDB Postgres Advanced Server and is installed as part of the Database Server component. You don't need to further install or configure it.

The pg_upgrade utility performs an in-place transfer of existing data between EDB Postgres Advanced Server and any later version.

Before performing a version upgrade, pg_upgrade verifies that the old cluster and the new cluster are compatible.

When pg_upgrade starts, it performs a compatibility check to ensure that all required executables are present and contain the expected version numbers. The verification process also checks the old and new $PGDATA directories to ensure that the expected files and subdirectories are in place. If the verification process succeeds, pg_upgrade starts the old postmaster and runs pg_dumpall --schema-only to capture the metadata contained in the old cluster. The script produced by pg_dumpall is used in later to re-create all user-defined objects in the new cluster.

The script produced by pg_dumpall re-creates only user-defined objects and not system-defined objects. The new cluster already contains the system-defined objects created by the latest version of EDB Postgres Advanced Server.

After extracting the metadata from the old cluster, pg_upgrade performs the bookkeeping tasks required to sync the new cluster with the existing data.

pg_upgrade runs the pg_dumpall script against the new cluster to create empty database objects of the same shape and type as those found in the old cluster. Then, pg_upgrade links or copies each table and index from the old cluster to the new cluster.

If you're upgrading to EDB Postgres Advanced Server and installed the edb_dblink_oci or edb_dblink_libpq extension, drop the extension before performing an upgrade. To drop the extension, connect to the server with the psql or PEM client, and invoke the commands:

DROP EXTENSION edb_dblink_oci;
DROP EXTENSION edb_dblink_libpq;

When you finish upgrading, you can use the CREATE EXTENSION command to add the current versions of the extensions to your installation.