initdb(1) PostgreSQL 17.4 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.
Creating a database cluster consists of creating the directories in
which the cluster 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 22.3 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 (see Section 23.1.4).
The libc locale provider takes the locale settings from the
environment, and determines the encoding from the locale settings.
To choose a different locale for the cluster, use the option --locale.
There are also individual options --lc-* and --icu-locale (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, initdb can use the ICU library to provide locale
services by specifying --locale-provider=icu. The server must be built
with ICU support. 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 23.1.
To alter the default encoding, use the --encoding. More details can be
found in Section 23.3.
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 20.1
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 data 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 character sets supported by the PostgreSQL
server are described in Section 23.3.1.
By default, the template database encoding is derived from the
locale. If --no-locale is specified (or equivalently, if the locale
is C or POSIX), then the default is UTF8 for the ICU provider and
SQL_ASCII for the libc provider.
-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 when the ICU provider is used. Locale
support is described in Section 23.1.
--icu-rules=rules
Specifies additional collation rules to customize the behavior of
the default collation. This is supported for ICU only.
-k
--data-checksums
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. See Section 28.2 for
details.
--locale=locale
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.
If --locale-provider is builtin, --locale or --builtin-locale must
be specified and set to C or C.UTF-8.
--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.
--builtin-locale=locale
Specifies the locale name when the builtin provider is used. Locale
support is described in Section 23.1.
--locale-provider={builtin|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
(see Section 23.1.4).
--pwfile=filename
Makes initdb read the bootstrap superuser's password from a file.
The first line of the file is taken as the password.
-T config
--text-search-config=config
Sets the default text search configuration. See
default_text_search_config for further information.
-U username
--username=username
Sets the user name of the bootstrap superuser. This defaults to the
name of the operating-system user running initdb.
-W
--pwprompt
Makes initdb prompt for a password to give the bootstrap 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.
-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:
-c name=value
--set name=value
Forcibly set the server parameter name to value during initdb, and
also install that setting in the generated postgresql.conf file, so
that it will apply during future server runs. This option can be
given more than once to set several parameters. It is primarily
useful when the environment is such that the server will not start
at all using the default parameters.
-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.
-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.
-s
--show
Show internal settings and exit, without doing anything else. This
can be used to debug the initdb installation.
--sync-method=method
When set to fsync, which is the default, initdb will recursively
open and synchronize all files in the data directory. The search
for files will follow symbolic links for the WAL directory and each
configured tablespace.
On Linux, syncfs may be used instead to ask the operating system to
synchronize the whole file systems that contain the data directory,
the WAL files, and each tablespace. See recovery_init_sync_method
for information about the caveats to be aware of when using syncfs.
This option has no effect when --no-sync is used.
-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.
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;
can be overridden using the -D option.
PG_COLOR
Specifies whether to use color in diagnostic messages. Possible
values are always, auto and never.
TZ
Specifies the default time zone of the created database cluster.
The value should be a full time zone name (see Section 8.5.3).
NOTES
initdb can also be invoked via pg_ctl initdb.
SEE ALSO
pg_ctl(1), postgres(1), Section 20.1
PostgreSQL 17.4 2025 initdb(1)
postgresql 17.4 - Generated Sat Mar 22 11:37:24 CDT 2025