PG_UPGRADE(1) PostgreSQL 9.5.0 Documentation PG_UPGRADE(1)NAMEpg_upgrade - upgrade a PostgreSQL server instance
SYNOPSISpg_upgrade-b oldbindir -B newbindir -d olddatadir -D newdatadir
[option...]
DESCRIPTIONpg_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.
OPTIONSpg_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; 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.
pgcrypto.sql, 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. Verify standby servers: If you are upgrading Streaming Replication
and Log-Shipping standby servers, 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.)
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 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, follow these steps to upgrade them. You will not
be running pg_upgrade on the standby servers, but rather rsync. Do
not start any servers yet. 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 server
data directories. Install custom shared object files: Install the
same custom shared object files on the new standbys that you
installed in the new master 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 standbys you need to keep, e.g. postgresql.conf,
recovery.conf, as these will be overwritten or removed in the next
step. Start and stop the new master cluster: In the new master
cluster, change wal_level to hot_standby in the postgresql.conf
file and then start and stop the cluster. Run rsync: From a
directory that is above the old and new database cluster
directories, run this for each slave:
rsync --archive --delete --hard-links --size-only old_pgdata new_pgdata remote_dir
where old_pgdata and new_pgdata are relative to the current
directory, and remote_dir is above the old and new cluster
directories on the standby server. The old and new relative cluster
paths must match on the master and standby server. Consult the
rsync manual page for details on specifying the remote directory,
e.g. standbyhost:/opt/PostgreSQL/. rsync will be fast when
pg_upgrade's --link mode is used because it will create hard links
on the remote server rather than transferring user data.
If you have tablespaces, you will need to run a similar rsync
command for each tablespace directory. 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 slaves are still synchronized with the
master.)
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.
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 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.
NOTESpg_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 ALSOinitdb(1), pg_ctl(1), pg_dump(1), postgres(1)PostgreSQL 9.5.0 2016 PG_UPGRADE(1)
