Ubuntu Manpage: pg_upgrade - upgrade a PostgreSQL server instance

Provided by: postgresql-9.3_9.3.24-0ubuntu0.14.04_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 8.3.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 old_bindir, --old-bindir=old_bindir
           the old PostgreSQL executable directory; environment variable PGBINOLD

       -B new_bindir, --new-bindir=new_bindir
           the new PostgreSQL executable directory; environment variable PGBINNEW

       -c, --check
           check clusters only, don't change any data

       -d old_datadir, --old-datadir=old_datadir
           the old cluster data directory; environment variable PGDATAOLD

       -D new_datadir, --new-datadir=new_datadir
           the new cluster data directory; environment variable PGDATANEW

       -j, --jobs
           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

       -O options, --new-options options
           options to be passed directly to the new postgres command

       -p old_port_number, --old-port=old_portnum
           the old cluster port number; environment variable PGPORTOLD

       -P new_port_number, --new-port=new_portnum
           the new cluster port number; environment variable PGPORTNEW

       -r, --retain
           retain SQL and log files even after successful completion

       -u user_name, --user=user_name
           cluster's super user name; environment variable PGUSER

       -v, --verbose
           enable verbose internal logging

       -V, --version
           display version information, then exit

       -?, -h, --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.

For source installs, if you wish to install the new server in a custom location, use the prefix
variable:

gmake prefix=/usr/local/pgsql.new install

4. Install pg_upgrade and pg_upgrade_support: Install the pg_upgrade binary and pg_upgrade_support
library in the new PostgreSQL installation.

5. 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.

6. 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. pgcrypto.sql, because these will be upgraded from the
old 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 31.15, “The
Password File”, in the documentation).

8. 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

NET STOP pgsql-8.3 (PostgreSQL 8.3 and older used a different service name)

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 14 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. 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.

11. 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.

12. 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.

13. 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. You can also delete the old
installation directories (e.g. bin, share).

14. Reverting to old cluster: If, after running pg_upgrade, you wish to revert to the old cluster, there
are several options:

• If you ran pg_upgrade with --check, no modifications were made to the old cluster and you can
re-use it anytime.

• If you ran pg_upgrade with --link, the data files are shared between the old and new cluster. If
you started the new cluster, the new server has written to those shared files and it is unsafe to
use the old cluster.

• If you ran pg_upgrade without --link or did not start the new server, the old cluster was not
modified except that, if linking started, a .old suffix was appended to
$PGDATA/global/pg_control. To reuse the old cluster, possibly remove the .old suffix from
$PGDATA/global/pg_control; you can then restart the old cluster.

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.)

A Log-Shipping Standby Server (Section 25.2, “Log-Shipping Standby Servers”, in the documentation) cannot
be upgraded because the server must allow writes. The simplest way is to upgrade the primary and use
rsync to rebuild the standbys. You can run rsync while the primary is down, or as part of a base backup
(Section 24.3.2, “Making a Base Backup”, in the documentation) which overwrites the old standby cluster.

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 again to update the copy with any changes to make it consistent. 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.

Limitations in Upgrading from PostgreSQL 8.3
Upgrading from PostgreSQL 8.3 has additional restrictions not present when upgrading from later
PostgreSQL releases. For example, pg_upgrade will not work for upgrading from 8.3 if a user column is
defined as:

• a tsquery data type

• data type name and is not the first column

You must drop any such columns and upgrade them manually.

pg_upgrade will not work if the ltree contrib module is installed in a database.

pg_upgrade will require a table rebuild if:

• a user column is of data type tsvector

pg_upgrade will require a reindex if:

• an index is of type hash or GIN

• an index uses bpchar_pattern_ops

Also, the default datetime storage format changed to integer after PostgreSQL 8.3. pg_upgrade will check
that the datetime storage format used by the old and new clusters match. Make sure your new cluster is
built with the configure flag --disable-integer-datetimes.