CREATE DATABASE

CREATE DATABASE

7

SQL - Language Statements

CREATE DATABASE

create a new database

CREATE DATABASE

name

\[ \[ WITH \] \[ OWNER \[=\]

user\_name

\] \[ TEMPLATE \[=\]

template

\] \[ ENCODING \[=\]

encoding

\] \[ STRATEGY \[=\]

strategy

\] \] \[ LOCALE \[=\]

locale

\] \[ LC\_COLLATE \[=\]

lc\_collate

\] \[ LC\_CTYPE \[=\]

lc\_ctype

\] \[ ICU\_LOCALE \[=\]

icu\_locale

\] \[ LOCALE\_PROVIDER \[=\]

locale\_provider

\] \[ COLLATION\_VERSION =

collation\_version

\] \[ TABLESPACE \[=\]

tablespace\_name

\] \[ ALLOW\_CONNECTIONS \[=\]

allowconn

\] \[ CONNECTION LIMIT \[=\]

connlimit

\] \[ IS\_TEMPLATE \[=\]

istemplate

\] \[ OID \[=\]

oid

\] \]

Description
===========

`CREATE DATABASE` creates a new PostgreSQL database.

To create a database, you must be a superuser or have the special
`CREATEDB` privilege. See [???](#sql-createrole).

By default, the new database will be created by cloning the standard
system database `template1`. A different template can be specified by
writing `TEMPLATE
   name`. In particular, by writing `TEMPLATE template0`, you can create
a pristine database (one where no user-defined objects exist and where
the system objects have not been altered) containing only the standard
objects predefined by your version of PostgreSQL. This is useful if you
wish to avoid copying any installation-local objects that might have
been added to `template1`.

Parameters
==========

name

:   The name of a database to create.

user\_name

:   The role name of the user who will own the new database, or
    `DEFAULT` to use the default (namely, the user executing the
    command). To create a database owned by another role, you must be a
    direct or indirect member of that role, or be a superuser.

template

:   The name of the template from which to create the new database, or
    `DEFAULT` to use the default template (`template1`).

encoding

:   Character set encoding to use in the new database. Specify a string
    constant (e.g., `'SQL_ASCII'`), or an integer encoding number, or
    `DEFAULT` to use the default encoding (namely, the encoding of the
    template database). The character sets supported by the PostgreSQL
    server are described in [???](#multibyte-charset-supported). See
    below for additional restrictions.

strategy

:   Strategy to be used in creating the new database. If the `WAL_LOG`
    strategy is used, the database will be copied block by block and
    each block will be separately written to the write-ahead log. This
    is the most efficient strategy in cases where the template database
    is small, and therefore it is the default. The older `FILE_COPY`
    strategy is also available. This strategy writes a small record to
    the write-ahead log for each tablespace used by the target database.
    Each such record represents copying an entire directory to a new
    location at the filesystem level. While this does reduce the
    write-ahead log volume substantially, especially if the template
    database is large, it also forces the system to perform a checkpoint
    both before and after the creation of the new database. In some
    situations, this may have a noticeable negative impact on overall
    system performance.

locale

:   This is a shortcut for setting `LC_COLLATE` and `LC_CTYPE` at once.
    If you specify this, you cannot specify either of those parameters.

    > **Tip**
    >
    > The other locale settings [???](#guc-lc-messages),
    > [???](#guc-lc-monetary), [???](#guc-lc-numeric), and
    > [???](#guc-lc-time) are not fixed per database and are not set by
    > this command. If you want to make them the default for a specific
    > database, you can use `ALTER DATABASE
    >          ... SET`.

lc\_collate

:   Collation order (`LC_COLLATE`) to use in the new database. This
    affects the sort order applied to strings, e.g., in queries with
    ORDER BY, as well as the order used in indexes on text columns. The
    default is to use the collation order of the template database. See
    below for additional restrictions.

lc\_ctype

:   Character classification (`LC_CTYPE`) to use in the new database.
    This affects the categorization of characters, e.g., lower, upper
    and digit. The default is to use the character classification of the
    template database. See below for additional restrictions.

icu\_locale

:   Specifies the ICU locale ID if the ICU locale provider is used.

locale\_provider

:   Specifies the provider to use for the default collation in this
    database. Possible values are: `icu`,ICU `libc`. `libc` is the
    default. The available choices depend on the operating system and
    build options.

collation\_version

:   Specifies the collation version string to store with the database.
    Normally, this should be omitted, which will cause the version to be
    computed from the actual version of the database collation as
    provided by the operating system. This option is intended to be used
    by `pg_upgrade` for copying the version from an existing
    installation.

    See also [???](#sql-alterdatabase) for how to handle database
    collation version mismatches.

tablespace\_name

:   The name of the tablespace that will be associated with the new
    database, or `DEFAULT` to use the template database\'s tablespace.
    This tablespace will be the default tablespace used for objects
    created in this database. See [???](#sql-createtablespace) for more
    information.

allowconn

:   If false then no one can connect to this database. The default is
    true, allowing connections (except as restricted by other
    mechanisms, such as `GRANT`/`REVOKE CONNECT`).

connlimit

:   How many concurrent connections can be made to this database. -1
    (the default) means no limit.

istemplate

:   If true, then this database can be cloned by any user with
    `CREATEDB` privileges; if false (the default), then only superusers
    or the owner of the database can clone it.

oid

:   The object identifier to be used for the new database. If this
    parameter is not specified, PostgreSQL will choose a suitable OID
    automatically. This parameter is primarily intended for internal use
    by pg\_upgrade, and only pg\_upgrade can specify a value less
    than 16384.

Optional parameters can be written in any order, not only the order
illustrated above.

Notes
=====

`CREATE DATABASE` cannot be executed inside a transaction block.

Errors along the line of "could not initialize database directory" are
most likely related to insufficient permissions on the data directory, a
full disk, or other file system problems.

Use [`DROP DATABASE`](#sql-dropdatabase) to remove a database.

The program [???](#app-createdb) is a wrapper program around this
command, provided for convenience.

Database-level configuration parameters (set via
[`ALTER DATABASE`](#sql-alterdatabase)) and database-level permissions
(set via [`GRANT`](#sql-grant)) are not copied from the template
database.

Although it is possible to copy a database other than `template1` by
specifying its name as the template, this is not (yet) intended as a
general-purpose "`COPY DATABASE`" facility. The principal limitation is
that no other sessions can be connected to the template database while
it is being copied. `CREATE
   DATABASE` will fail if any other connection exists when it starts;
otherwise, new connections to the template database are locked out until
`CREATE DATABASE` completes. See [???](#manage-ag-templatedbs) for more
information.

The character set encoding specified for the new database must be
compatible with the chosen locale settings (`LC_COLLATE` and
`LC_CTYPE`). If the locale is `C` (or equivalently `POSIX`), then all
encodings are allowed, but for other locale settings there is only one
encoding that will work properly. (On Windows, however, UTF-8 encoding
can be used with any locale.) `CREATE DATABASE` will allow superusers to
specify `SQL_ASCII` encoding regardless of the locale settings, but this
choice is deprecated and may result in misbehavior of character-string
functions if data that is not encoding-compatible with the locale is
stored in the database.

The encoding and locale settings must match those of the template
database, except when `template0` is used as template. This is because
other databases might contain data that does not match the specified
encoding, or might contain indexes whose sort ordering is affected by
`LC_COLLATE` and `LC_CTYPE`. Copying such data would result in a
database that is corrupt according to the new settings. `template0`,
however, is known to not contain any data or indexes that would be
affected.

There is currently no option to use a database locale with
nondeterministic comparisons (see [`CREATE
   COLLATION`](#sql-createcollation) for an explanation). If this is
needed, then per-column collations would need to be used.

The `CONNECTION LIMIT` option is only enforced approximately; if two new
sessions start at about the same time when just one connection "slot"
remains for the database, it is possible that both will fail. Also, the
limit is not enforced against superusers or background worker processes.

Examples
========

To create a new database:

    CREATE DATABASE lusiadas;

To create a database `sales` owned by user `salesapp` with a default
tablespace of `salesspace`:

    CREATE DATABASE sales OWNER salesapp TABLESPACE salesspace;

To create a database `music` with a different locale:

    CREATE DATABASE music
        LOCALE 'sv_SE.utf8'
        TEMPLATE template0;

In this example, the `TEMPLATE template0` clause is required if the
specified locale is different from the one in `template1`. (If it is
not, then specifying the locale explicitly is redundant.)

To create a database `music2` with a different locale and a different
character set encoding:

    CREATE DATABASE music2
        LOCALE 'sv_SE.iso885915'
        ENCODING LATIN9
        TEMPLATE template0;

The specified locale and encoding settings must match, or an error will
be reported.

Note that locale names are specific to the operating system, so that the
above commands might not work in the same way everywhere.

Compatibility
=============

There is no `CREATE DATABASE` statement in the SQL standard. Databases
are equivalent to catalogs, whose creation is implementation-defined.

See Also
========
