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.