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 24.1.
To alter the default encoding, use the --encoding.
More details can be found in Section 24.3.
-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 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 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.
-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 30.2 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 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.
-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-onlySafely write all database files to disk and exit. This does not perform any of the normal initdb operations.
-T config--text-search-config=configSets 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.
-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=directoryThis option specifies the directory where the write-ahead log should be stored.
--wal-segsize=sizeSet 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--versionPrint the initdb version and exit.
-?--helpShow help about initdb command line arguments, and exit.
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.
TZSpecifies 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).
initdb can also be invoked via
pg_ctl initdb.