Before you can do anything, you must initialize a database storage
area on disk. We call this a database cluster.
(SQL uses the term catalog cluster instead.) A
database cluster is a collection of databases is accessible by a
single instance of a running database server. After initialization, a
database cluster will contain a database named
template1. As the name suggests, this will be used
as a template for subsequently created databases; it should not be
used for actual work. (See Chapter 32 for information
about creating databases.)
Note: The default database cluster is created and initialized automatically
when you run our installers, and the following steps are only needed if you
intend to perform this step manually.
In file system terms, a database cluster will be a single directory
under which all data will be stored. We call this the data
directory or data area. It is
completely up to you where you choose to store your data. There is no
default, although a location such as
/opt/EnterpriseDB/8.2.1.2/data is popular. To initialize a
database cluster, use the command initdb, which is
installed with EnterpriseDB. The desired
file system location of your database system is indicated by the
-D option, for example
$ initdb -D /opt/EnterpriseDB/8.2.1.2/data
Note that you must execute this command while logged into the
EnterpriseDB user account, which is
described in the previous section.
Tip: As an alternative to the -D option, you can set
the environment variable PGDATA.
initdb will attempt to create the directory you
specify if it does not already exist. It is likely that it will not
have the permission to do so (if you followed our advice and created
an unprivileged account). In that case you should create the
directory yourself (as root) and change the owner to be the
EnterpriseDB user. Here is how this might
be done:
root# mkdir /opt/EnterpriseDB/8.2.1.2/data
root# chown enterprisedb /opt/EnterpriseDB/8.2.1.2/data
root# su enterprisedb
enterprisedb$ initdb -D /opt/EnterpriseDB/8.2.1.2/data
initdb will refuse to run if the data directory
looks like it it has already been initialized.
Because the data directory contains all the data stored in the
database, it is essential that it be secured from unauthorized
access. initdb therefore revokes access
permissions from everyone but the
EnterpriseDB user.
However, while the directory contents are secure, the default
client authentication setup allows any local user to connect to the
database and even become the database superuser. If you do not
trust other local users, we recommend you use one of
initdb's -W, --pwprompt
or --pwfile option to assign a password to the
database superuser. After initdb, modify
the pg_hba.conf file to use md5 or
password instead of trust authentication
before you start the server for the first time. (Other
approaches include using ident authentication or
file system permissions to restrict connections. See Chapter 33 for more information.)
initdb also initializes the default
locale for the database cluster.
Normally, it will just take the locale settings in the environment
and apply them to the initialized database. It is possible to
specify a different locale for the database; more information about
that can be found in Section 34.1. The sort order used
within a particular database cluster is set by
initdb and cannot be changed later, short of
dumping all data, rerunning initdb, and
reloading the data. So it's important to make this choice correctly
the first time.