forked from pool/postgresql15
81 lines
3.8 KiB
Plaintext
81 lines
3.8 KiB
Plaintext
|
Unix-Domain Socket Directory
|
||
|
|
============================
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
Upgrading PostgreSQL on openSUSE and SUSE Linux Enterprise Server
|
||
|
|
=================================================================
|
||
|
|
|
||
|
|
Current versions of PostgreSQL come with the pg_upgrade tool that
|
||
|
|
simplifies and speeds up the migration of a PostgreSQL installation to
|
||
|
|
a new version. Before version 9.1 dump and restore was needed which
|
||
|
|
was much slower.
|
||
|
|
|
||
|
|
pg_upgrade needs to have the server binaries of both versions
|
||
|
|
available. To allow this, we had to change the way PostgreSQL is
|
||
|
|
packaged as well as the naming of the packages, so that two or more
|
||
|
|
versions of PostgreSQL can be installed in parallel. The package
|
||
|
|
names for PostgreSQL contain numbers indicating the major version.
|
||
|
|
|
||
|
|
In PostgreSQL terms for versions up to 9.6 the major version consisted
|
||
|
|
of the first two components of the three-component version number,
|
||
|
|
i.e. 8.3, 8.4, 9.0, or 9.1. So, the packages for Postgresql 9.1 are
|
||
|
|
named postgresql91, postgresql91-server, etc. Inside the packages the
|
||
|
|
files were moved from their standard locations to a versioned location
|
||
|
|
such as /usr/lib/postgresql83/bin or /usr/lib/postgresql91/bin to
|
||
|
|
avoid file conflicts if packages are installed in parallel.
|
||
|
|
|
||
|
|
Starting with version 10 the PostgreSQL project changed their
|
||
|
|
versioning scheme from from three components to two, which means one
|
||
|
|
component for the major version and one for the minor. So, the
|
||
|
|
sequence of major version across the versioning scheme change will be:
|
||
|
|
9.4, 9.5, 9.6, 10, 11, 12. For versions that use the new versioning
|
||
|
|
scheme SUSE only puts the single component major version into the
|
||
|
|
package name, so the postgresql96 package (containg version 9.6
|
||
|
|
according to the old versioning scheme) will be followed by
|
||
|
|
postgresql10, then postgresql11, and so on.
|
||
|
|
|
||
|
|
The update-alternatives mechanism creates and maintains symbolic links
|
||
|
|
that cause one version (by default the highest installed version) to
|
||
|
|
re-appear in the standard locations. By default, database data are
|
||
|
|
stored under /var/lib/pgsql/data on SUSE Linux.
|
||
|
|
|
||
|
|
The following preconditions have to be fulfilled before data migration
|
||
|
|
can be started:
|
||
|
|
|
||
|
|
1. If not already done, the packages of the old PostgreSQL version
|
||
|
|
must be upgraded to the new packaging scheme through a maintenance
|
||
|
|
update.
|
||
|
|
|
||
|
|
2. The packages of the new PostgreSQL major version need to be
|
||
|
|
installed. As pg_upgrade is contained in postgresql91-contrib, that
|
||
|
|
one has to be installed as well, at least until the migration is
|
||
|
|
done.
|
||
|
|
|
||
|
|
3. Unless pg_upgrade is used in link mode, the server must have
|
||
|
|
enough free disk space to temporarily hold a copy of the database
|
||
|
|
files. If the database instance was installed in the default
|
||
|
|
location, the needed space in megabytes can be determined by running
|
||
|
|
the follwing command as root: "du -hs /var/lib/pgsql/data". If space
|
||
|
|
is tight, it might help to run the "VACUUM FULL" SQL command on each
|
||
|
|
database in the instance to be migrated, but be aware that it might
|
||
|
|
take very long.
|
||
|
|
|
||
|
|
The latest upstream documentation for pg_upgrade including step by
|
||
|
|
step instructions for performing a database migration can be found
|
||
|
|
online under https://www.postgresql.org/docs/current/pgupgrade.html ,
|
||
|
|
or locally under
|
||
|
|
file:///usr/share/doc/packages/postgresqlXX/html/pgupgrade.html , if
|
||
|
|
the postgresqlXX-docs package is installed. XX is a place holder for
|
||
|
|
the respective major version here.
|
||
|
|
|
||
|
|
NOTE: The online documentation starts with explaining how you can
|
||
|
|
install PostgreSQL from the upstream sources (which is not necessary
|
||
|
|
when you install the SUSE RPMs) and also uses other directory names
|
||
|
|
(/usr/local instead of the update-alternatives based path as described
|
||
|
|
above).
|
||
|
|
|
||
|
|
For background information about the inner workings of pg_upgrade and
|
||
|
|
a performance comparison with the old dump and restore method, see
|
||
|
|
http://momjian.us/main/writings/pgsql/pg_upgrade.pdf .
|