initdb

initdb

1

Application

initdb

create a new

PostgreSQL

database cluster

initdb

option

\--pgdata

-D

directory

Description {#r1-app-initdb-1}
===========

`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 [???](#manage-ag-templatedbs) 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 chose 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 [???](#locale).

To alter the default encoding, use the `--encoding`. More details can be
found in [???](#multibyte).

Options
=======

`-A authmethod`; `--auth=authmethod`

:   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
    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, or
    `SQL_ASCII` if that does not work. The character sets supported by
    the PostgreSQL server are described in
    [???](#multibyte-charset-supported).

`-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
    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](#monitoring-pg-stat-database-view) view. See
    [???](#checksums) 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 [???](#locale).

`--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
    [???](#guc-fsync) from `off` to `on`.

`-T config`; `--text-search-config=config`

:   Sets the default text search configuration. See
    [???](#guc-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.

`-W`; `--pwprompt`

:   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.

`-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;
    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
    [???](#datatype-timezones)).

This utility, like most other PostgreSQL utilities, also uses the
environment variables supported by libpq (see [???](#libpq-envars)).

Notes
=====

`initdb` can also be invoked via `pg_ctl initdb`.

See Also
========
