pg_upgrade — upgrade a PostgreSQL™ server instance
pg_upgrade
-b
oldbindir
-B
newbindir
-d
olddatadir
-D
newdatadir
[option
...]
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.
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
, --jobs
number of simultaneous processes or threads to use
-k
, --link
use hard links instead of copying files to the new cluster (use junction points on Windows)
-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
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 super user name; environment
variable PGUSER
-v
, --verbose
enable verbose internal logging
-V
, --version
display version information, then exit
-?
, --help
show help, then exit
These are the steps to perform an upgrade with pg_upgrade:
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.
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.
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:
make prefix=/usr/local/pgsql.new install
Install pg_upgrade and pg_upgrade_support
Install the pg_upgrade binary and pg_upgrade_support library in the new PostgreSQL installation.
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.
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.
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 the section called “The Password File”).
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
or
NET STOP pgsql-8.3 (PostgreSQL™ 8.3 and older used a different service name)
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.
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
.
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.
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.
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.
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
).
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.
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 (the section called “Log-Shipping Standby Servers”) 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 (the section called “Making a Base Backup”) 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 the section called “Making a Base Backup Using the Low Level API”. 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.
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
.
For Windows users, note that due to different integer datetimes settings used by the graphical installer and the MSI installer, it is only possible to upgrade from version 8.3 of the installer distribution to version 8.4 or later of the installer distribution. It is not possible to upgrade from the MSI installer to the new graphical installer.