initdb(1) - phpMan
INITDB(1) PostgreSQL 12.3 Documentation INITDB(1)
initdb - create a new PostgreSQL database cluster
initdb [option...] [--pgdata | -D] directory
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 template1 and postgres
databases. When you later create a new database, everything in the template1 database is
copied. (Therefore, anything installed in template1 is automatically copied into each
database created later.) The postgres database is a default database meant for use by
users, utilities and third party applications.
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. The
character set encoding, collation order (LC_COLLATE) and character set classes (LC_CTYPE,
e.g. upper, lower, digit) can be set separately for a database when it is created. initdb
determines those settings for the template1 database, which will serve as the default for
all other databases.
To alter the default collation order or character set classes, use the --lc-collate and
--lc-ctype options. Collation orders other than C or POSIX also have a performance
penalty. For these reasons it is important to choose the right locale when running initdb.
The remaining locale categories can be changed later when the server is started. You can
also use --locale to set the default for all locale categories, including collation order
and character set classes. All server locale values (lc_*) can be displayed via SHOW ALL.
More details can be found in Section 23.1.
To alter the default encoding, use the --encoding. More details can be found in
This option specifies the default authentication method for local users used in
pg_hba.conf (host and local lines). initdb will prepopulate pg_hba.conf entries using
the specified authentication method for non-replication as well as replication
Do not use trust unless you trust all local users on your system. trust is the
default for ease of installation.
This option specifies the authentication method for local users via TCP/IP connections
used in pg_hba.conf (host lines).
This option specifies the authentication method for local users via Unix-domain socket
connections used in pg_hba.conf (local lines).
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.
Selects the encoding of the template database. This will also be the default encoding
of any database you create later, unless you override it there. The default is derived
from the locale, or SQL_ASCII if that does not work. The character sets supported by
the PostgreSQL server are described in Section 23.3.1.
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
Use checksums on data pages to help detect corruption by the I/O system that would
otherwise be silent. Enabling checksums may incur a noticeable performance penalty. If
set, checksums are calculated for all objects, in all databases. All checksum failures
will be reported in the pg_stat_database view.
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 23.1.
Like --locale, but only sets the locale in the specified category.
Equivalent to --locale=C.
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.
Makes initdb read the database superuser's password from a file. The first line of the
file is taken as the password.
Safely write all database files to disk and exit. This does not perform any of the
normal initdb operations.
Sets the default text search configuration. See default_text_search_config for further
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.
Makes initdb prompt for a password to give the database superuser. If you don't plan
on using password authentication, this is not important. Otherwise you won't be able
to use password authentication until you have a password set up.
This option specifies the directory where the write-ahead log should be stored.
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:
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
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
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
Print the initdb version and exit.
Show help about initdb command line arguments, and exit.
Specifies the directory where the database cluster is to be stored; can be overridden
using the -D option.
Specifies whether to use color in diagnostic messages. Possible values are always,
auto and never.
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 33.14).
initdb can also be invoked via pg_ctl initdb.
PostgreSQL 12.3 2020 INITDB(1)