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INITDB(1) PostgreSQL 15.4 Documentation INITDB(1)
NAME initdb - create a new PostgreSQL database cluster
SYNOPSIS initdb [option...] [--pgdata | -D] directory
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 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.
OPTIONS -A authmethod --auth=authmethod This option specifies the default authentication method for local users used in pg_hba.conf (host and local lines). See Section 21.1 for an overview of valid values.
initdb will prepopulate pg_hba.conf entries using the specified authentication method for non-replication as well as replication connections.
Do not use trust unless you trust all local users on your system. trust is the default for ease of installation.
--auth-host=authmethod This option specifies the authentication method for local users via TCP/IP connections used in pg_hba.conf (host lines).
--auth-local=authmethod This option specifies the authentication method for local users via Unix-domain socket connections used in pg_hba.conf (local lines).
-D directory --pgdata=directory This option specifies the directory where the database cluster should be stored. This is the only information required by initdb, but you can avoid writing it by setting the PGDATA environment variable, which can be convenient since the database server (postgres) can find the database directory later by the same variable.
-E encoding --encoding=encoding Selects the encoding of the template databases. This will also be the default encoding of any database you create later, unless you override it then. The default is derived from the locale, if the libc locale provider is used, or UTF8 if the ICU locale provider is used. The character sets supported by the PostgreSQL server are described in Section 24.3.1.
-g --allow-group-access Allows users in the same group as the cluster owner to read all cluster files created by initdb. This option is ignored on Windows as it does not support POSIX-style group permissions.
--icu-locale=locale Specifies the ICU locale ID, if the ICU locale provider is used.
-k --data-checksums Use checksums on data pages to help detect corruption by the I/O Sets the default locale for the database cluster. If this option is not specified, the locale is inherited from the environment that initdb runs in. Locale support is described in Section 24.1.
--lc-collate=locale --lc-ctype=locale --lc-messages=locale --lc-monetary=locale --lc-numeric=locale --lc-time=locale Like --locale, but only sets the locale in the specified category.
--no-locale Equivalent to --locale=C.
--locale-provider={libc|icu} This option sets the locale provider for databases created in the new cluster. It can be overridden in the CREATE DATABASE command when new databases are subsequently created. The default is libc.
-N --no-sync By default, initdb will wait for all files to be written safely to disk. This option causes initdb to return without waiting, which is faster, but means that a subsequent operating system crash can leave the data directory corrupt. Generally, this option is useful for testing, but should not be used when creating a production installation.
--no-instructions By default, initdb will write instructions for how to start the cluster at the end of its output. This option causes those instructions to be left out. This is primarily intended for use by tools that wrap initdb in platform-specific behavior, where those instructions are likely to be incorrect.
--pwfile=filename Makes initdb read the database superuser's password from a file. The first line of the file is taken as the password.
-S --sync-only Safely write all database files to disk and exit. This does not perform any of the normal initdb operations. Generally, this option is useful for ensuring reliable recovery after changing fsync from off to on.
-T config --text-search-config=config Sets the default text search configuration. See default_text_search_config for further information.
-U username --username=username Selects the user name of the database superuser. This defaults to the name of the effective user running initdb. It is really not important what the superuser's name is, but one might choose to keep the customary name postgres, even if the operating system user's name is different.
-X directory --waldir=directory This option specifies the directory where the write-ahead log should be stored.
--wal-segsize=size Set the WAL segment size, in megabytes. This is the size of each individual file in the WAL log. The default size is 16 megabytes. The value must be a power of 2 between 1 and 1024 (megabytes). This option can only be set during initialization, and cannot be changed later.
It may be useful to adjust this size to control the granularity of WAL log shipping or archiving. Also, in databases with a high volume of WAL, the sheer number of WAL files per directory can become a performance and management problem. Increasing the WAL file size will reduce the number of WAL files.
Other, less commonly used, options are also available:
-d --debug Print debugging output from the bootstrap backend and a few other messages of lesser interest for the general public. The bootstrap backend is the program initdb uses to create the catalog tables. This option generates a tremendous amount of extremely boring output.
--discard-caches Run the bootstrap backend with the debug_discard_caches=1 option. This takes a very long time and is only of use for deep debugging.
-L directory Specifies where initdb should find its input files to initialize the database cluster. This is normally not necessary. You will be told if you need to specify their location explicitly.
-n --no-clean By default, when initdb determines that an error prevented it from completely creating the database cluster, it removes any files it might have created before discovering that it cannot finish the job. This option inhibits tidying-up and is thus useful for debugging.
Other options:
-V --version Print the initdb version and exit.
-? --help Show help about initdb command line arguments, and exit.
ENVIRONMENT PGDATA Specifies the directory where the database cluster is to be stored; Specifies the default time zone of the created database cluster. The value should be a full time zone name (see Section 8.5.3).
This utility, like most other PostgreSQL utilities, also uses the environment variables supported by libpq (see Section 34.15).
NOTES initdb can also be invoked via pg_ctl initdb.
SEE ALSO pg_ctl(1), postgres(1), Section 21.1
PostgreSQL 15.4 2023 INITDB(1)