It is possible to create a database in a location other than the
default location for the installation. Remember that all database access
occurs through the
database server, so any location specified must be
accessible by the server.
Alternative database locations are referenced by an environment
variable which gives the absolute path to the intended storage
location. This environment variable must be present in the server's
environment, so it must have been defined before the server
was started. (Thus, the set of available alternative locations is
under the site administrator's control; ordinary users can't
change it.) Any valid environment variable name may
be used to reference an alternative location, although using
variable names with a prefix of PGDATA is recommended
to avoid confusion and conflict with other variables.
To create the variable in the environment of the server process
you must first shut down the server, define the variable,
initialize the data area, and finally restart the server. (See
Section 3.6 and Section 3.3.) To set an environment variable, type
PGDATA2=/home/postgres/data
export PGDATA2
in Bourne shells, or
setenv PGDATA2 /home/postgres/data
in csh or tcsh. You have to make sure that this environment
variable is always defined in the server environment, otherwise
you won't be able to access that database. Therefore you probably
want to set it in some sort of shell start-up file or server
start-up script.
To create a data storage area in PGDATA2, ensure that
the containing directory (here, /home/postgres)
already exists and is writable
by the user account that runs the server (see Section 3.1). Then from the command line, type
initlocation PGDATA2
(not initlocation
$PGDATA2). Then you can restart the server.
To create a database within the new location, use the command
CREATE DATABASE name WITH LOCATION = 'location'
where location is the environment variable you
used, PGDATA2 in this example. The createdb
command has the option -D for this purpose.
Databases created in alternative locations can be
accessed and dropped like any other database.
Note: It can also be possible to specify absolute paths directly to the
CREATE DATABASE command without defining environment
variables. This is disallowed by default because it is a security
risk. To allow it, you must compile PostgreSQL with
the C preprocessor macro ALLOW_ABSOLUTE_DBPATHS
defined. One way to do this is to run the compilation step like
this:
gmake CPPFLAGS=-DALLOW_ABSOLUTE_DBPATHS all
