initdb — create a new PostgreSQL database cluster
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
postgres databases. When you later create a
new database, everything in the
template1 database is copied. (Therefore,
anything installed in
automatically copied into each database created later.) The
postgres database is a default
database meant for use by users, utilities and third party
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
to become the database user to run
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
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
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
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-ctype options. Collation
orders other than
POSIX also have a performance
penalty. For these reasons it is important to choose the right
locale when running
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
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
initdb will prepopulate
pg_hba.conf entries using the specified
authentication method for non-replication as well as
Do not use
you trust all local users on your system.
trust is the default for ease of
This option specifies the authentication method for
local users via TCP/IP connections used in
This option specifies the authentication method for
local users via Unix-domain socket connections used in
This option specifies the directory where the database
cluster should be stored. This is the only information
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
Allows users in the same group as the cluster owner to
read all cluster files created by
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. This option can only be set during initialization, and cannot be changed later. If set, checksums are calculated for all objects, in all databases.
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.
--locale, but only
sets the locale in the specified category.
wait for all files to be written safely to disk. This
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
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 information.
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.
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 boring output.
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.
By default, when
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.
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
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 34.14).
initdb can also be invoked via