|PG_UPGRADE(1)||PostgreSQL 14.3 Documentation||PG_UPGRADE(1)|
pg_upgrade - upgrade a PostgreSQL server instance
pg_upgrade -b oldbindir [-B newbindir] -d oldconfigdir -D newconfigdir [option...]
pg_upgrade (formerly called pg_migrator) allows data stored in PostgreSQL data files to be upgraded to a later PostgreSQL major version without the data dump/reload typically required for major version upgrades, e.g., from 9.5.8 to 9.6.4 or from 10.7 to 11.2. It is not required for minor version upgrades, e.g., from 9.6.2 to 9.6.3 or from 10.1 to 10.2.
Major PostgreSQL releases regularly add new features that often change the layout of the system tables, but the internal data storage format rarely changes. pg_upgrade uses this fact to perform rapid upgrades by creating new system tables and simply reusing the old user data files. If a future major release ever changes the data storage format in a way that makes the old data format unreadable, pg_upgrade will not be usable for such upgrades. (The community will attempt to avoid such situations.)
pg_upgrade does its best to make sure the old and new clusters are binary-compatible, e.g., by checking for compatible compile-time settings, including 32/64-bit binaries. It is important that any external modules are also binary compatible, though this cannot be checked by pg_upgrade.
pg_upgrade supports upgrades from 8.4.X and later to the current major release of PostgreSQL, including snapshot and beta releases.
pg_upgrade accepts the following command-line arguments:
File cloning is only supported on some operating systems and file systems. If it is selected but not supported, the pg_upgrade run will error. At present, it is supported on Linux (kernel 4.5 or later) with Btrfs and XFS (on file systems created with reflink support), and on macOS with APFS.
These are the steps to perform an upgrade with pg_upgrade:
If your installation directory is not version-specific, e.g., /usr/local/pgsql, it is necessary to move the current PostgreSQL install directory so it does not interfere with the new PostgreSQL installation. Once the current PostgreSQL server is shut down, it is safe to rename the PostgreSQL installation directory; assuming the old directory is /usr/local/pgsql, you can do:
mv /usr/local/pgsql /usr/local/pgsql.old
to rename the directory.
For source installs, if you wish to install the new server in a custom location, use the prefix variable:
make prefix=/usr/local/pgsql.new install
pg_ctl -D /opt/PostgreSQL/9.6 stop pg_ctl -D /opt/PostgreSQL/14 stop
or on Windows, using the proper service names:
NET STOP postgresql-9.6 NET STOP postgresql-14
Streaming replication and log-shipping standby servers can remain running until a later step.
If you use link mode, the upgrade will be much faster (no file copying) and use less disk space, but you will not be able to access your old cluster once you start the new cluster after the upgrade. Link mode also requires that the old and new cluster data directories be in the same file system. (Tablespaces and pg_wal can be on different file systems.) Clone mode provides the same speed and disk space advantages but does not cause the old cluster to be unusable once the new cluster is started. Clone mode also requires that the old and new data directories be in the same file system. This mode is only available on certain operating systems and file systems.
The --jobs option allows multiple CPU cores to be used for copying/linking of files and to dump and reload database schemas in parallel; a good place to start is the maximum of the number of CPU cores and tablespaces. This option can dramatically reduce the time to upgrade a multi-database server running on a multiprocessor machine.
For Windows users, you must be logged into an administrative account, and then start a shell as the postgres user and set the proper path:
RUNAS /USER:postgres "CMD.EXE" SET PATH=%PATH%;C:\Program Files\PostgreSQL\14\bin;
and then run pg_upgrade with quoted directories, e.g.:
--old-datadir "C:/Program Files/PostgreSQL/9.6/data"
--new-datadir "C:/Program Files/PostgreSQL/14/data"
--old-bindir "C:/Program Files/PostgreSQL/9.6/bin"
--new-bindir "C:/Program Files/PostgreSQL/14/bin"
Once started, pg_upgrade will verify the two clusters are compatible and then do the upgrade. You can use pg_upgrade --check to perform only the checks, even if the old server is still running. pg_upgrade --check will also outline any manual adjustments you will need to make after the upgrade. If you are going to be using link or clone mode, you should use the option --link or --clone with --check to enable mode-specific checks. pg_upgrade requires write permission in the current directory.
Obviously, no one should be accessing the clusters during the upgrade. pg_upgrade defaults to running servers on port 50432 to avoid unintended client connections. You can use the same port number for both clusters when doing an upgrade because the old and new clusters will not be running at the same time. However, when checking an old running server, the old and new port numbers must be different.
If an error occurs while restoring the database schema, pg_upgrade will exit and you will have to revert to the old cluster as outlined in Step 17 below. To try pg_upgrade again, you will need to modify the old cluster so the pg_upgrade schema restore succeeds. If the problem is a contrib module, you might need to uninstall the contrib module from the old cluster and install it in the new cluster after the upgrade, assuming the module is not being used to store user data.
If you did not use link mode, do not have or do not want to use rsync, or want an easier solution, skip the instructions in this section and simply recreate the standby servers once pg_upgrade completes and the new primary is running. Install the new PostgreSQL binaries on standby servers: Make sure the new binaries and support files are installed on all standby servers. Make sure the new standby data directories do not exist: Make sure the new standby data directories do not exist or are empty. If initdb was run, delete the standby servers' new data directories. Install extension shared object files: Install the same extension shared object files on the new standbys that you installed in the new primary cluster. Stop standby servers: If the standby servers are still running, stop them now using the above instructions. Save configuration files: Save any configuration files from the old standbys' configuration directories you need to keep, e.g., postgresql.conf (and any files included by it), postgresql.auto.conf, pg_hba.conf, because these will be overwritten or removed in the next step. Run rsync: When using link mode, standby servers can be quickly upgraded using rsync. To accomplish this, from a directory on the primary server that is above the old and new database cluster directories, run this on the primary for each standby server:
rsync --archive --delete --hard-links --size-only --no-inc-recursive old_cluster new_cluster remote_dir
where old_cluster and new_cluster are relative to the current directory on the primary, and remote_dir is above the old and new cluster directories on the standby. The directory structure under the specified directories on the primary and standbys must match. Consult the rsync manual page for details on specifying the remote directory, e.g.,
rsync --archive --delete --hard-links --size-only --no-inc-recursive /opt/PostgreSQL/9.5 \
You can verify what the command will do using rsync's --dry-run option. While rsync must be run on the primary for at least one standby, it is possible to run rsync on an upgraded standby to upgrade other standbys, as long as the upgraded standby has not been started.
What this does is to record the links created by pg_upgrade's link mode that connect files in the old and new clusters on the primary server. It then finds matching files in the standby's old cluster and creates links for them in the standby's new cluster. Files that were not linked on the primary are copied from the primary to the standby. (They are usually small.) This provides rapid standby upgrades. Unfortunately, rsync needlessly copies files associated with temporary and unlogged tables because these files don't normally exist on standby servers.
If you have tablespaces, you will need to run a similar rsync command for each tablespace directory, e.g.:
rsync --archive --delete --hard-links --size-only --no-inc-recursive /vol1/pg_tblsp/PG_9.5_201510051 \
If you have relocated pg_wal outside the data directories, rsync must be run on those directories too. Configure streaming replication and log-shipping standby servers: Configure the servers for log shipping. (You do not need to run pg_start_backup() and pg_stop_backup() or take a file system backup as the standbys are still synchronized with the primary.)
psql --username=postgres --file=script.sql postgres
The scripts can be run in any order and can be deleted once they have been run.
In general it is unsafe to access tables referenced in rebuild scripts until the rebuild scripts have run to completion; doing so could yield incorrect results or poor performance. Tables not referenced in rebuild scripts can be accessed immediately.
pg_upgrade creates various working files, such as schema dumps, in the current working directory. For security, be sure that that directory is not readable or writable by any other users.
pg_upgrade launches short-lived postmasters in the old and new data directories. Temporary Unix socket files for communication with these postmasters are, by default, made in the current working directory. In some situations the path name for the current directory might be too long to be a valid socket name. In that case you can use the -s option to put the socket files in some directory with a shorter path name. For security, be sure that that directory is not readable or writable by any other users. (This is not supported on Windows.)
All failure, rebuild, and reindex cases will be reported by pg_upgrade if they affect your installation; post-upgrade scripts to rebuild tables and indexes will be generated automatically. If you are trying to automate the upgrade of many clusters, you should find that clusters with identical database schemas require the same post-upgrade steps for all cluster upgrades; this is because the post-upgrade steps are based on the database schemas, and not user data.
For deployment testing, create a schema-only copy of the old cluster, insert dummy data, and upgrade that.
pg_upgrade does not support upgrading of databases containing table columns using these reg* OID-referencing system data types:
If you are upgrading a pre-PostgreSQL 9.2 cluster that uses a configuration-file-only directory, you must pass the real data directory location to pg_upgrade, and pass the configuration directory location to the server, e.g., -d /real-data-directory -o '-D /configuration-directory'.
If using a pre-9.1 old server that is using a non-default Unix-domain socket directory or a default that differs from the default of the new cluster, set PGHOST to point to the old server's socket location. (This is not relevant on Windows.)
If you want to use link mode and you do not want your old cluster to be modified when the new cluster is started, consider using the clone mode. If that is not available, make a copy of the old cluster and upgrade that in link mode. To make a valid copy of the old cluster, use rsync to create a dirty copy of the old cluster while the server is running, then shut down the old server and run rsync --checksum again to update the copy with any changes to make it consistent. (--checksum is necessary because rsync only has file modification-time granularity of one second.) You might want to exclude some files, e.g., postmaster.pid, as documented in Section 26.3.3. If your file system supports file system snapshots or copy-on-write file copies, you can use that to make a backup of the old cluster and tablespaces, though the snapshot and copies must be created simultaneously or while the database server is down.