Performing an Upgrade Overview v12

To upgrade an earlier version of Advanced Server to the current version, you must:

• Install the current version of Advanced Server. The new installation must contain the same supporting server components as the old installation.
• Empty the target database or create a new target cluster with initdb.
• Place the pg_hba.conf file for both databases in trust authentication mode (to avoid authentication conflicts).
• Shut down the old and new Advanced Server services.
• Invoke the pg_upgrade utility.

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 a later step to recreate all user-defined objects in the new cluster.

Note that the script produced by pg_dumpall recreates only user-defined objects and not system-defined objects. The new cluster will already contain the system-defined objects created by the latest version of 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 are upgrading to Advanced Server 12 and have installed the edb_dblink_oci or edb_dblink_libpq extension, you must 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 have completed upgrading, you can use the CREATE EXTENSION command to add the current versions of the extensions to your installation.