PG_UPGRADE(1)

📦 version 17.11, in opensuse-leap 16.0

💖 NAME 💖

pg_upgrade — upgrade a PostgreSQL server instance. That’s the whole main-character job of PG_UPGRADE(1), straight from the PostgreSQL 17.11 documentation, bestie. 💅

✨ SYNOPSIS ✨

pg_upgrade -b oldbindir [-B newbindir] -d oldconfigdir -D newconfigdir
           [option...]

💖 DESCRIPTION 💖

Okay so pg_upgrade (formerly called pg_migrator, cute throwback) lets data stored in PostgreSQL data files be upgraded to a later PostgreSQL major version without the whole data dump/restore situation that major version upgrades typically require, e.g., from 12.14 to 13.10 or from 14.9 to 15.5. It is not required for minor version upgrades, e.g., from 12.7 to 12.8 or from 14.1 to 14.5. Minor upgrades already have main-character energy on their own.

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.) So like, no cap, this is the speedy path when the storage format stays readable.

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. Lowkey important: it cannot verify external modules for you.

pg_upgrade supports upgrades from 9.2.X and later to the current major release of PostgreSQL, including snapshot and beta releases. ✨

⚠️ Warning — Upgrading a cluster causes the destination to execute arbitrary code of the source superusers' choice. Ensure that the source superusers are trusted before upgrading. 🔥

🎀 OPTIONS 🎀

pg_upgrade accepts the following command-line arguments:

  • -b bindir / --old-bindir=bindir — the old PostgreSQL executable directory; environment variable PGBINOLD.
  • -B bindir / --new-bindir=bindir — the new PostgreSQL executable directory; default is the directory where pg_upgrade resides; environment variable PGBINNEW.
  • -c, --check — check clusters only, don't change any data.
  • -d configdir / --old-datadir=configdir — the old database cluster configuration directory; environment variable PGDATAOLD.
  • -D configdir / --new-datadir=configdir — the new database cluster configuration directory; environment variable PGDATANEW.
  • -j njobs / --jobs=njobs — number of simultaneous processes or threads to use.
  • -k, --link — use hard links instead of copying files to the new cluster.
  • -N, --no-sync — By default, pg_upgrade will wait for all files of the upgraded cluster to be written safely to disk. This option causes pg_upgrade to return without waiting, which is faster, but means that a subsequent operating system crash can leave the data directory corrupt. Generally, this option is useful for testing but should not be used on a production installation. ⚠️
  • -o options / --old-options options — options to be passed directly to the old postgres command; multiple option invocations are appended.
  • -O options / --new-options options — options to be passed directly to the new postgres command; multiple option invocations are appended.
  • -p port / --old-port=port — the old cluster port number; environment variable PGPORTOLD.
  • -P port / --new-port=port — the new cluster port number; environment variable PGPORTNEW.
  • -r, --retain — retain SQL and log files even after successful completion.
  • -s dir / --socketdir=dir — directory to use for postmaster sockets during upgrade; default is current working directory; environment variable PGSOCKETDIR.
  • -U username / --username=username — cluster's install user name; environment variable PGUSER.
  • -v, --verbose — enable verbose internal logging.
  • -V, --version — display version information, then exit.
  • --clone — Use efficient file cloning (also known as “reflinks” on some systems) instead of copying files to the new cluster. This can result in near-instantaneous copying of the data files, giving the speed advantages of -k/--link while leaving the old cluster untouched. 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. 🦋
  • --copy — Copy files to the new cluster. This is the default. (See also --link and --clone.)
  • --copy-file-range — Use the copy_file_range system call for efficient copying. On some file systems this gives results similar to --clone, sharing physical disk blocks, while on others it may still copy blocks, but do so via an optimized path. At present, it is supported on Linux and FreeBSD.
  • --sync-method=method — When set to fsync, which is the default, pg_upgrade will recursively open and synchronize all files in the upgraded cluster's data directory. The search for files will follow symbolic links for the WAL directory and each configured tablespace. On Linux, syncfs may be used instead to ask the operating system to synchronize the whole file systems that contain the upgraded cluster's data directory, its WAL files, and each tablespace. See recovery_init_sync_method for information about the caveats to be aware of when using syncfs. This option has no effect when --no-sync is used.
  • -?, --help — show help, then exit.

🦋 USAGE 🦋

These are the steps to perform an upgrade with pg_upgrade. Do not skip steps, iykyk. 🫶

  1. Optionally move the old cluster: If you are using a version-specific installation directory, e.g., /opt/PostgreSQL/17, you do not need to move the old cluster. The graphical installers all use version-specific installation directories.

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.

  1. For source installs, build the new version: Build the new PostgreSQL source with configure flags that are compatible with the old cluster. pg_upgrade will check pg_controldata to make sure all settings are compatible before starting the upgrade.
  2. Install the new PostgreSQL binaries: Install the new server's binaries and support files. pg_upgrade is included in a default installation.

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
  1. Initialize the new PostgreSQL cluster: Initialize the new cluster using initdb. Again, use compatible initdb flags that match the old cluster. Many prebuilt installers do this step automatically. There is no need to start the new cluster.
  2. Install extension shared object files: Many extensions and custom modules, whether from contrib or another source, use shared object files (or DLLs), e.g., pgcrypto.so. If the old cluster used these, shared object files matching the new server binary must be installed in the new cluster, usually via operating system commands. Do not load the schema definitions, e.g., CREATE EXTENSION pgcrypto, because these will be duplicated from the old cluster. If extension updates are available, pg_upgrade will report this and create a script that can be run later to update them.
  3. Copy custom full-text search files: Copy any custom full text search files (dictionary, synonym, thesaurus, stop words) from the old to the new cluster.
  4. Adjust authentication: pg_upgrade will connect to the old and new servers several times, so you might want to set authentication to peer in pg_hba.conf or use a ~/.pgpass file (see Section 32.16).
  5. Prepare for publisher upgrades: pg_upgrade attempts to migrate logical slots. This helps avoid the need for manually defining the same logical slots on the new publisher. Migration of logical slots is only supported when the old cluster is version 17.0 or later. Logical slots on clusters before version 17.0 will silently be ignored.

Before you start upgrading the publisher cluster, ensure that the subscription is temporarily disabled, by executing ALTER SUBSCRIPTION ... DISABLE. Re-enable the subscription after the upgrade.

There are some prerequisites for pg_upgrade to be able to upgrade the logical slots. If these are not met an error will be reported.

  • The new cluster must have wal_level as logical.
  • The new cluster must have max_replication_slots configured to a value greater than or equal to the number of slots present in the old cluster.
  • The output plugins referenced by the slots in the old cluster must be installed in the new PostgreSQL executable directory. They must also be included in the new cluster's output_plugin_libraries; see that parameter's documentation for safety information.
  • The old cluster has replicated all the transactions and logical decoding messages to subscribers.
  • All slots on the old cluster must be usable, i.e., there are no slots whose pg_replication_slots.conflicting is not true.
  • The new cluster must not have permanent logical slots, i.e., there must be no slots where pg_replication_slots.temporary is false.
  1. Prepare for subscriber upgrades: Setup the subscriber configurations in the new subscriber. pg_upgrade attempts to migrate subscription dependencies which includes the subscription's table information present in pg_subscription_rel system catalog and also the subscription's replication origin. This allows logical replication on the new subscriber to continue from where the old subscriber was up to. Migration of subscription dependencies is only supported when the old cluster is version 17.0 or later. Subscription dependencies on clusters before version 17.0 will silently be ignored. 💜

There are a few prerequisites before pg_upgrade can upgrade your subscriptions, bestie — if any of them aren't met, it's gonna throw an error at you. 💅

  • All the subscription tables in the old subscriber should be in state i (initialize) or r (ready). You can verify this by checking pg_subscription_rel.srsubstate.
  • The replication origin entry corresponding to each of the subscriptions should exist in the old cluster. You can find that by checking the pg_subscription and pg_replication_origin system tables.
  • The new cluster must have max_replication_slots configured to a value greater than or equal to the number of subscriptions present in the old cluster.
  1. Stop both servers — okay so make sure both database servers are stopped, using on Unix, e.g.:
pg_ctl -D /opt/PostgreSQL/12 stop
pg_ctl -D /opt/PostgreSQL/17 stop

or on Windows, using the proper service names:

NET STOP postgresql-12
NET STOP postgresql-17

Streaming replication and log-shipping standby servers must be running during this shutdown so they receive all changes. Yes, running. Don't touch them. 🫶

  1. Prepare for standby server upgrades — if you're upgrading standby servers using the methods outlined in Step 13, verify that the old standby servers are caught up by running pg_controldata against the old primary and standby clusters. Verify that the "Latest checkpoint location" values match in all clusters. Also, make sure wal_level is not set to minimal in the postgresql.conf file on the new primary cluster.
  2. Run pg_upgrade — always run the pg_upgrade binary of the new server, not the old one. Not me stressing this again but like. fr fr. pg_upgrade requires the specification of the old and new cluster's data and executable (bin) directories. You can also specify user and port values, and whether you want the data files linked or cloned instead of the default copy behavior.

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 restore 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. Literally giving speed. 🔥

For Windows users, you must be logged into an administrative account, and then run pg_upgrade with quoted directories, e.g.:

pg_upgrade.exe
        --old-datadir "C:/Program Files/PostgreSQL/12/data"
        --new-datadir "C:/Program Files/PostgreSQL/17/data"
        --old-bindir "C:/Program Files/PostgreSQL/12/bin"
        --new-bindir "C:/Program Files/PostgreSQL/17/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 19 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. 😭
  1. Upgrade streaming replication and log-shipping standby servers — if you used link mode and have Streaming Replication (see Section 26.2.5) or Log-Shipping (see Section 26.2) standby servers, you can follow these steps to quickly upgrade them. You will not be running pg_upgrade on the standby servers, but rather rsync on the primary. Do not start any servers yet. 🙈

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.

  1. Install the new PostgreSQL binaries on standby servers — make sure the new binaries and support files are installed on all standby servers.
  2. 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.
  3. Install extension shared object files — install the same extension shared object files on the new standbys that you installed in the new primary cluster.
  4. Stop standby servers — if the standby servers are still running, stop them now using the above instructions.
  5. 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.
  6. 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/12 \
      /opt/PostgreSQL/17 standby.example.com:/opt/PostgreSQL

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_12_201909212 \
      /vol1/pg_tblsp/PG_17_202307071 standby.example.com:/vol1/pg_tblsp

If you have relocated pg_wal outside the data directories, rsync must be run on those directories too.

  1. Configure streaming replication and log-shipping standby servers — configure the servers for log shipping. (You do not need to run pg_backup_start() and pg_backup_stop() or take a file system backup as the standbys are still synchronized with the primary.) If the old primary is prior to version 17.0, then no slots on the primary are copied to the new standby, so all the slots on the old standby must be recreated manually. If the old primary is version 17.0 or later, then only logical slots on the primary are copied to the new standby, but other slots on the old standby are not copied, so must be recreated manually.
  1. Restore pg_hba.conf — if you modified pg_hba.conf, restore its original settings. It might also be necessary to adjust other configuration files in the new cluster to match the old cluster, e.g., postgresql.conf (and any files included by it), postgresql.auto.conf. 🎀
  2. Start the new server — the new server can now be safely started, and then any rsync'ed standby servers. ✨
  3. Post-upgrade processing — if any post-upgrade processing is required, pg_upgrade will issue warnings as it completes. It will also generate script files that must be run by the administrator. The script files will connect to each database that needs post-upgrade processing. Each script should be run using:
psql --username=postgres --file=script.sql postgres

The scripts can be run in any order and can be deleted once they have been run. Slay, you're basically done. 🌈

🚨 Caution

ngl bestie, this is the part where you do not touch stuff. 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, so like, check first, okay? 💅
  1. Statistics 🌸 — because optimizer statistics are not transferred by pg_upgrade, you'll be told to run a command to regenerate that info at the end of the upgrade. You might need to set connection parameters to match your new cluster.

Using vacuumdb --all --analyze-only can efficiently generate such statistics, and the use of --jobs can speed it up. Option --analyze-in-stages can be used to generate minimal statistics quickly. If vacuum_cost_delay is set to a non-zero value, this can be overridden to speed up statistics generation using PGOPTIONS, e.g.:

PGOPTIONS='-c vacuum_cost_delay=0' vacuumdb ....
  1. Delete old cluster 🗑️ — once you are satisfied with the upgrade, you can delete the old cluster's data directories by running the script mentioned when pg_upgrade completes. (Automatic deletion is not possible if you have user-defined tablespaces inside the old data directory.) You can also delete the old installation directories (e.g., bin, share).
  2. Reverting to old cluster 😭 — if, after running pg_upgrade, you wish to revert to the old cluster, there are several options:
    • If the --check option was used, the old cluster was unmodified; it can be restarted. ✨
    • If the --link option was not used, the old cluster was unmodified; it can be restarted.
    • If the --link option was used, the data files might be shared between the old and new cluster:
      • If pg_upgrade aborted before linking started, the old cluster was unmodified; it can be restarted.
      • If you did not start the new cluster, the old cluster was unmodified except that, when linking started, a .old suffix was appended to $PGDATA/global/pg_control. To reuse the old cluster, remove the .old suffix from $PGDATA/global/pg_control; you can then restart the old cluster.
      • If you did start the new cluster, it has written to shared files and it is unsafe to use the old cluster. The old cluster will need to be restored from backup in this case. 💀

🌈 ENVIRONMENT 🌈

Some environment variables can be used to provide defaults for command-line options, bestie — set 'em and skip the flags:

  • PGBINOLD — the old PostgreSQL executable directory; option -b/--old-bindir.
  • PGBINNEW — the new PostgreSQL executable directory; option -B/--new-bindir.
  • PGDATAOLD — the old database cluster configuration directory; option -d/--old-datadir.
  • PGDATANEW — the new database cluster configuration directory; option -D/--new-datadir.
  • PGPORTOLD — the old cluster port number; option -p/--old-port.
  • PGPORTNEW — the new cluster port number; option -P/--new-port.
  • PGSOCKETDIR — directory to use for postmaster sockets during upgrade; option -s/--socketdir.
  • PGUSER — cluster's install user name; option -U/--username.

🦋 NOTES 🦋

pg_upgrade creates various working files, such as schema dumps, stored within pg_upgrade_output.d in the directory of the new cluster. Each run creates a new subdirectory named with a timestamp formatted as per ISO 8601 (%Y%m%dT%H%M%S), where all its generated files are stored. pg_upgrade_output.d and its contained files will be removed automatically if pg_upgrade completes successfully; but in the event of trouble, the files there may provide useful debugging information. 🙈

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. Chef's kiss testing strategy, honestly. 👑

pg_upgrade does not support upgrading of databases containing table columns using these reg* OID-referencing system data types:

  • regcollation
  • regconfig
  • regdictionary
  • regnamespace
  • regoper
  • regoperator
  • regproc
  • regprocedure

(regclass, regrole, and regtype can be upgraded.) ⭐

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 25.3.4. 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. 🌸

💖 SEE ALSO 💖

initdb(1), pg_ctl(1), pg_dump(1), postgres(1)

okay that's the whole page bestie, you're officially a pg_upgrade girlie now 🫶 this was PostgreSQL 17.11, dated 2026, page PG_UPGRADE(1) — go forth and upgrade responsibly, mwah 💋✨

📦 where this page comes from