Provided by: postgresql-12_12.18-0ubuntu0.20.04.1_amd64 
NAME
pg_upgrade - upgrade a PostgreSQL server instance
SYNOPSIS
pg_upgrade -b oldbindir -B newbindir -d oldconfigdir -D newconfigdir [option...]
DESCRIPTION
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/restore 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.
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; 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
-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.
-?
--help
show help, then exit
USAGE
These are the steps to perform an upgrade with pg_upgrade:
1. Optionally move the old cluster: If you are using a version-specific installation
directory, e.g., /opt/PostgreSQL/12, 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.
2. 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.
3. 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
4. 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.
5. 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.
6. 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.
7. 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 33.15).
8. Stop both servers: Make sure both database servers are stopped using, on Unix, e.g.:
pg_ctl -D /opt/PostgreSQL/9.6 stop
pg_ctl -D /opt/PostgreSQL/12 stop
or on Windows, using the proper service names:
NET STOP postgresql-9.6
NET STOP postgresql-12
Streaming replication and log-shipping standby servers must be running during this
shutdown so they receive all changes.
9. Prepare for standby server upgrades: If you are upgrading standby servers using
methods outlined in section Step 11, 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.
10. Run pg_upgrade: Always run the pg_upgrade binary of the new server, not the old one.
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.
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\12\bin;
and then run pg_upgrade with quoted directories, e.g.:
pg_upgrade.exe
--old-datadir "C:/Program Files/PostgreSQL/9.6/data"
--new-datadir "C:/Program Files/PostgreSQL/12/data"
--old-bindir "C:/Program Files/PostgreSQL/9.6/bin"
--new-bindir "C:/Program Files/PostgreSQL/12/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.
11. 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. 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 \
/opt/PostgreSQL/9.6 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_9.5_201510051 \
/vol1/pg_tblsp/PG_9.6_201608131 standby.example.com:/vol1/pg_tblsp
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.) Replication slots are not copied and must be recreated.
12. 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.
13. Start the new server: The new server can now be safely started, and then any rsync'ed
standby servers.
14. 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.
Caution
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.
15. Statistics: Because optimizer statistics are not transferred by pg_upgrade, you will
be instructed to run a command to regenerate that information at the end of the
upgrade. You might need to set connection parameters to match your new cluster.
16. 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).
17. 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.
NOTES
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 relevant 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: regproc, regprocedure, regoper, regoperator,
regconfig, and regdictionary. (regtype can be upgraded.)
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 25.3.3. 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.
SEE ALSO
initdb(1), pg_ctl(1), pg_dump(1), postgres(1)