PostgreSQL: Documentation: 15: initdb

Description

initdb creates a new PostgreSQL database cluster. A database cluster is a collection of databases that are managed by a single server instance.

Creating a database cluster consists of creating the directories in which the database data will live, generating the shared catalog tables (tables that belong to the whole cluster rather than to any particular database), and creating the postgres, template1, and template0 databases. The postgres database is a default database meant for use by users, utilities and third party applications. template1 and template0 are meant as source databases to be copied by later CREATE DATABASE commands. template0 should never be modified, but you can add objects to template1, which by default will be copied into databases created later. See Section 23.3 for more details.

Although initdb will attempt to create the specified data directory, it might not have permission if the parent directory of the desired data directory is root-owned. To initialize in such a setup, create an empty data directory as root, then use chown to assign ownership of that directory to the database user account, then su to become the database user to run initdb.

initdb must be run as the user that will own the server process, because the server needs to have access to the files and directories that initdb creates. Since the server cannot be run as root, you must not run initdb as root either. (It will in fact refuse to do so.)

For security reasons the new cluster created by initdb will only be accessible by the cluster owner by default. The --allow-group-access option allows any user in the same group as the cluster owner to read files in the cluster. This is useful for performing backups as a non-privileged user.

initdb initializes the database cluster's default locale and character set encoding. These can also be set separately for each database when it is created. initdb determines those settings for the template databases, which will serve as the default for all other databases. By default, initdb uses the locale provider libc, takes the locale settings from the environment, and determines the encoding from the locale settings. This is almost always sufficient, unless there are special requirements.

To choose a different locale for the cluster, use the option --locale. There are also individual options --lc-* (see below) to set values for the individual locale categories. Note that inconsistent settings for different locale categories can give nonsensical results, so this should be used with care.

Alternatively, the ICU library can be used to provide locale services. (Again, this only sets the default for subsequently created databases.) To select this option, specify --locale-provider=icu. To choose the specific ICU locale ID to apply, use the option --icu-locale. Note that for implementation reasons and to support legacy code, initdb will still select and initialize libc locale settings when the ICU locale provider is used.

When initdb runs, it will print out the locale settings it has chosen. If you have complex requirements or specified multiple options, it is advisable to check that the result matches what was intended.

More details about locale settings can be found in Section 24.1.

To alter the default encoding, use the --encoding. More details can be found in Section 24.3.