Provided by: postgresql-9.5_9.5.25-0ubuntu0.16.04.1_amd64 
NAME
pg_upgrade - upgrade a PostgreSQL server instance
SYNOPSIS
pg_upgrade -b oldbindir -B newbindir -d olddatadir -D newdatadir [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/reload typically required for major version
upgrades, e.g., from 8.4.7 to the current major release of PostgreSQL. It is not required for minor
version upgrades, e.g., from 9.0.1 to 9.0.4.
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 alpha 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 datadir
--old-datadir=datadir
the old cluster data directory; environment variable PGDATAOLD
-D datadir
--new-datadir=datadir
the new cluster data 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
-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
-?
--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/9.1, 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 custom shared object files: Install any custom shared object files (or DLLs) used by the old
cluster into the new cluster, e.g., pgcrypto.so, whether they are from contrib or some other source.
Do not install the schema definitions, e.g., CREATE EXTENSION pgcrypto, because these will be
upgraded from the old cluster. Also, any custom full text search files (dictionary, synonym,
thesaurus, stop words) must also be copied to the new cluster.
6. 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 31.15, “The
Password File”, in the documentation).
7. Stop both servers: Make sure both database servers are stopped using, on Unix, e.g.:
pg_ctl -D /opt/PostgreSQL/8.4 stop
pg_ctl -D /opt/PostgreSQL/9.0 stop
or on Windows, using the proper service names:
NET STOP postgresql-8.4
NET STOP postgresql-9.0
Streaming replication and log-shipping standby servers can remain running until a later step.
8. Prepare for standby server upgrades: If you are upgrading standby servers using methods outlined in
section Step 10, 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. (There will be a mismatch if old standby servers were shut down before the old primary
or if the old standby servers are still running.) Also, make sure wal_level is not set to minimal in
the postgresql.conf file on the new primary cluster.
9. 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 linked instead of copied (the
default).
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_xlog can be on different file systems.) See pg_upgrade --help for a full list of
options.
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\9.0\bin;
and then run pg_upgrade with quoted directories, e.g.:
pg_upgrade.exe
--old-datadir "C:/Program Files/PostgreSQL/8.4/data"
--new-datadir "C:/Program Files/PostgreSQL/9.0/data"
--old-bindir "C:/Program Files/PostgreSQL/8.4/bin"
--new-bindir "C:/Program Files/PostgreSQL/9.0/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 mode, you should use the --link option with --check to enable
link-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 16 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.
10. Upgrade Streaming Replication and Log-Shipping standby servers: If you used link mode and have
Streaming Replication (see Section 25.2.5, “Streaming Replication”, in the documentation) or
Log-Shipping (see Section 25.2, “Log-Shipping Standby Servers”, in the documentation) 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 custom shared
object files: Install the same custom 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, recovery.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_xlog 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.)
11. 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.
12. Start the new server: The new server can now be safely started, and then any rsync'ed standby
servers.
13. 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.
14. 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.
15. 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).
16. 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 does not support upgrading of databases containing these reg* OID-referencing system data
types: regproc, regprocedure, regoper, regoperator, regconfig, and regdictionary. (regtype can be
upgraded.)
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.
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, 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 24.3.3, “Making a Base
Backup Using the Low Level API”, in the documentation. 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)
PostgreSQL 9.5.25 2021 PG_UPGRADE(1)