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PostgreSQL documentation
<refentry id="SQL-CREATETABLE">
<refmeta>
<refentrytitle>CREATE TABLE</refentrytitle>
<manvolnum>7</manvolnum>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
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<refname>CREATE TABLE</refname>
<refpurpose>define a new table</refpurpose>
</refnamediv>
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<indexterm zone="sql-createtable">
<primary>CREATE TABLE</primary>
</indexterm>
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<synopsis>
CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXISTS ] <replaceable class="PARAMETER">table_name</replaceable> ( [
{ <replaceable class="PARAMETER">column_name</replaceable> <replaceable class="PARAMETER">data_type</replaceable> [ COLLATE <replaceable>collation</replaceable> ] [ <replaceable class="PARAMETER">column_constraint</replaceable> [ ... ] ]
| <replaceable>table_constraint</replaceable>
| LIKE <replaceable>source_table</replaceable> [ <replaceable>like_option</replaceable> ... ] }
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[ INHERITS ( <replaceable>parent_table</replaceable> [, ... ] ) ]
[ WITH ( <replaceable class="PARAMETER">storage_parameter</replaceable> [= <replaceable class="PARAMETER">value</replaceable>] [, ... ] ) | WITH OIDS | WITHOUT OIDS ]
[ ON COMMIT { PRESERVE ROWS | DELETE ROWS | DROP } ]
[ TABLESPACE <replaceable class="PARAMETER">tablespace_name</replaceable> ]
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CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXISTS ] <replaceable class="PARAMETER">table_name</replaceable>
OF <replaceable class="PARAMETER">type_name</replaceable> [ (
{ <replaceable class="PARAMETER">column_name</replaceable> WITH OPTIONS [ <replaceable class="PARAMETER">column_constraint</replaceable> [ ... ] ]
| <replaceable>table_constraint</replaceable> }
[, ... ]
) ]
[ WITH ( <replaceable class="PARAMETER">storage_parameter</replaceable> [= <replaceable class="PARAMETER">value</replaceable>] [, ... ] ) | WITH OIDS | WITHOUT OIDS ]
[ ON COMMIT { PRESERVE ROWS | DELETE ROWS | DROP } ]
[ TABLESPACE <replaceable class="PARAMETER">tablespace_name</replaceable> ]
<phrase>where <replaceable class="PARAMETER">column_constraint</replaceable> is:</phrase>
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[ CONSTRAINT <replaceable class="PARAMETER">constraint_name</replaceable> ]
CHECK ( <replaceable class="PARAMETER">expression</replaceable> ) [ NO INHERIT ] |
DEFAULT <replaceable>default_expr</replaceable> |
UNIQUE <replaceable class="PARAMETER">index_parameters</replaceable> |
PRIMARY KEY <replaceable class="PARAMETER">index_parameters</replaceable> |
REFERENCES <replaceable class="PARAMETER">reftable</replaceable> [ ( <replaceable class="PARAMETER">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
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[ ON DELETE <replaceable class="parameter">action</replaceable> ] [ ON UPDATE <replaceable class="parameter">action</replaceable> ] }
[ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
<phrase>and <replaceable class="PARAMETER">table_constraint</replaceable> is:</phrase>
[ CONSTRAINT <replaceable class="PARAMETER">constraint_name</replaceable> ]
{ CHECK ( <replaceable class="PARAMETER">expression</replaceable> ) [ NO INHERIT ] |
UNIQUE ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] ) <replaceable class="PARAMETER">index_parameters</replaceable> |
PRIMARY KEY ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] ) <replaceable class="PARAMETER">index_parameters</replaceable> |
EXCLUDE [ USING <replaceable class="parameter">index_method</replaceable> ] ( <replaceable class="parameter">exclude_element</replaceable> WITH <replaceable class="parameter">operator</replaceable> [, ... ] ) <replaceable class="parameter">index_parameters</replaceable> [ WHERE ( <replaceable class="parameter">predicate</replaceable> ) ] |
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FOREIGN KEY ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] ) REFERENCES <replaceable class="PARAMETER">reftable</replaceable> [ ( <replaceable class="PARAMETER">refcolumn</replaceable> [, ... ] ) ]
[ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ] [ ON DELETE <replaceable class="parameter">action</replaceable> ] [ ON UPDATE <replaceable class="parameter">action</replaceable> ] }
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[ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
<phrase>and <replaceable class="PARAMETER">like_option</replaceable> is:</phrase>
{ INCLUDING | EXCLUDING } { DEFAULTS | CONSTRAINTS | INDEXES | STORAGE | COMMENTS | ALL }
<phrase><replaceable class="PARAMETER">index_parameters</replaceable> in <literal>UNIQUE</literal>, <literal>PRIMARY KEY</literal>, and <literal>EXCLUDE</literal> constraints are:</phrase>
[ WITH ( <replaceable class="PARAMETER">storage_parameter</replaceable> [= <replaceable class="PARAMETER">value</replaceable>] [, ... ] ) ]
[ USING INDEX TABLESPACE <replaceable class="PARAMETER">tablespace_name</replaceable> ]
<phrase><replaceable class="PARAMETER">exclude_element</replaceable> in an <literal>EXCLUDE</literal> constraint is:</phrase>
{ <replaceable class="parameter">column_name</replaceable> | ( <replaceable class="parameter">expression</replaceable> ) } [ <replaceable class="parameter">opclass</replaceable> ] [ ASC | DESC ] [ NULLS { FIRST | LAST } ]
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</synopsis>
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<refsect1 id="SQL-CREATETABLE-description">
<title>Description</title>
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<command>CREATE TABLE</command> will create a new, initially empty table
in the current database. The table will be owned by the user issuing the
</para>
<para>
If a schema name is given (for example, <literal>CREATE TABLE
myschema.mytable ...</>) then the table is created in the specified
schema. Otherwise it is created in the current schema. Temporary
tables exist in a special schema, so a schema name cannot be given
when creating a temporary table. The name of the table must be
distinct from the name of any other table, sequence, index, view,
or foreign table in the same schema.
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<command>CREATE TABLE</command> also automatically creates a data
type that represents the composite type corresponding
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to one row of the table. Therefore, tables cannot have the same
name as any existing data type in the same schema.
</para>
<para>
The optional constraint clauses specify constraints (tests) that
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new or updated rows must satisfy for an insert or update operation
to succeed. A constraint is an SQL object that helps define the
set of valid values in the table in various ways.
</para>
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There are two ways to define constraints: table constraints and
column constraints. A column constraint is defined as part of a
column definition. A table constraint definition is not tied to a
particular column, and it can encompass more than one column.
Every column constraint can also be written as a table constraint;
a column constraint is only a notational convenience for use when the
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constraint only affects one column.
<para>
To be able to create a table, you must have <literal>USAGE</literal>
privilege on all column types or the type in the <literal>OF</literal>
clause, respectively.
</para>
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<refsect1>
<title>Parameters</title>
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<variablelist>
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<varlistentry>
<term><literal>TEMPORARY</> or <literal>TEMP</></term>
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<listitem>
<para>
If specified, the table is created as a temporary table.
Temporary tables are automatically dropped at the end of a
session, or optionally at the end of the current transaction
(see <literal>ON COMMIT</literal> below). Existing permanent
tables with the same name are not visible to the current session
while the temporary table exists, unless they are referenced
with schema-qualified names. Any indexes created on a temporary
table are automatically temporary as well.
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</para>
<para>
The <link linkend="autovacuum">autovacuum daemon</link> cannot
access and therefore cannot vacuum or analyze temporary tables.
For this reason, appropriate vacuum and analyze operations should be
performed via session SQL commands. For example, if a temporary
table is going to be used in complex queries, it is wise to run
<command>ANALYZE</> on the temporary table after it is populated.
</para>
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<para>
Optionally, <literal>GLOBAL</literal> or <literal>LOCAL</literal>
can be written before <literal>TEMPORARY</> or <literal>TEMP</>.
This presently makes no difference in <productname>PostgreSQL</>
and is deprecated; see
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<xref linkend="sql-createtable-compatibility"
endterm="sql-createtable-compatibility-title">.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>UNLOGGED</></term>
<listitem>
<para>
If specified, the table is created as an unlogged table. Data written
to unlogged tables is not written to the write-ahead log (see <xref
linkend="wal">), which makes them considerably faster than ordinary
tables. However, they are not crash-safe: an unlogged table is
automatically truncated after a crash or unclean shutdown. The contents
of an unlogged table are also not replicated to standby servers.
Any indexes created on an unlogged table are automatically unlogged as
well; however, unlogged <link linkend="GiST">GiST indexes</link> are
currently not supported and cannot be created on an unlogged table.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>IF NOT EXISTS</></term>
<listitem>
<para>
Do not throw an error if a relation with the same name already exists.
A notice is issued in this case. Note that there is no guarantee that
the existing relation is anything like the one that would have been
created.
</para>
</listitem>
</varlistentry>
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<varlistentry>
<term><replaceable class="PARAMETER">table_name</replaceable></term>
<listitem>
<para>
The name (optionally schema-qualified) of the table to be created.
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</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>OF <replaceable class="PARAMETER">type_name</replaceable></literal></term>
<listitem>
<para>
Creates a <firstterm>typed table</firstterm>, which takes its
structure from the specified composite type (name optionally
schema-qualified). A typed table is tied to its type; for
example the table will be dropped if the type is dropped
(with <literal>DROP TYPE ... CASCADE</literal>).
</para>
<para>
When a typed table is created, then the data types of the
columns are determined by the underlying composite type and are
not specified by the <literal>CREATE TABLE</literal> command.
But the <literal>CREATE TABLE</literal> command can add defaults
and constraints to the table and can specify storage parameters.
</para>
</listitem>
</varlistentry>
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<varlistentry>
<term><replaceable class="PARAMETER">column_name</replaceable></term>
<listitem>
<para>
The name of a column to be created in the new table.
</para>
</listitem>
</varlistentry>
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<varlistentry>
<term><replaceable class="PARAMETER">data_type</replaceable></term>
<listitem>
<para>
The data type of the column. This can include array
specifiers. For more information on the data types supported by
<productname>PostgreSQL</productname>, refer to <xref
linkend="datatype">.
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</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>COLLATE <replaceable>collation</replaceable></literal></term>
<listitem>
<para>
The <literal>COLLATE</> clause assigns a collation to
the column (which must be of a collatable data type).
If not specified, the column data type's default collation is used.
</para>
</listitem>
</varlistentry>
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<varlistentry>
<term><literal>INHERITS ( <replaceable>parent_table</replaceable> [, ... ] )</literal></term>
<listitem>
<para>
The optional <literal>INHERITS</> clause specifies a list of
tables from which the new table automatically inherits all
columns.
</para>
<para>
Use of <literal>INHERITS</> creates a persistent relationship
between the new child table and its parent table(s). Schema
modifications to the parent(s) normally propagate to children
as well, and by default the data of the child table is included in
scans of the parent(s).
</para>
<para>
If the same column name exists in more than one parent
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table, an error is reported unless the data types of the columns
match in each of the parent tables. If there is no conflict,
then the duplicate columns are merged to form a single column in
the new table. If the column name list of the new table
contains a column name that is also inherited, the data type must
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likewise match the inherited column(s), and the column
definitions are merged into one. If the
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new table explicitly specifies a default value for the column,
this default overrides any defaults from inherited declarations
of the column. Otherwise, any parents that specify default
values for the column must all specify the same default, or an
error will be reported.
</para>
<para><literal>CHECK</> constraints are merged in essentially the same way as
columns: if multiple parent tables and/or the new table definition
contain identically-named <literal>CHECK</> constraints, these
constraints must all have the same check expression, or an error will be
reported. Constraints having the same name and expression will
be merged into one copy. A constraint marked <literal>NO INHERIT</> in a
parent will not be considered. Notice that an unnamed <literal>CHECK</>
constraint in the new table will never be merged, since a unique name
will always be chosen for it.
</para>
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<para>
Column <literal>STORAGE</> settings are also copied from parent tables.
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</para>
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</listitem>
</varlistentry>
<term><literal>LIKE <replaceable>source_table</replaceable> [ <replaceable>like_option</replaceable> ... ]</literal></term>
<listitem>
<para>
The <literal>LIKE</literal> clause specifies a table from which
the new table automatically copies all column names, their data types,
and their not-null constraints.
</para>
<para>
Unlike <literal>INHERITS</literal>, the new table and original table
are completely decoupled after creation is complete. Changes to the
original table will not be applied to the new table, and it is not
possible to include data of the new table in scans of the original
table.
</para>
<para>
Default expressions for the copied column definitions will only be
copied if <literal>INCLUDING DEFAULTS</literal> is specified. The
default behavior is to exclude default expressions, resulting in the
copied columns in the new table having null defaults.
Not-null constraints are always copied to the new table.
<literal>CHECK</literal> constraints will only be copied if
<literal>INCLUDING CONSTRAINTS</literal> is specified; other types of
constraints will never be copied. Also, no distinction is made between
column constraints and table constraints — when constraints are
requested, all check constraints are copied.
<para>
Any indexes on the original table will not be created on the new
table, unless the <literal>INCLUDING INDEXES</literal> clause is
specified.
</para>
<para><literal>STORAGE</> settings for the copied column definitions will only
be copied if <literal>INCLUDING STORAGE</literal> is specified. The
default behavior is to exclude <literal>STORAGE</> settings, resulting
in the copied columns in the new table having type-specific default
settings. For more on <literal>STORAGE</> settings, see
<xref linkend="storage-toast">.
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</para>
<para>
Comments for the copied columns, constraints, and indexes
will only be copied if <literal>INCLUDING COMMENTS</literal>
is specified. The default behavior is to exclude comments, resulting in
the copied columns and constraints in the new table having no comments.
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</para>
<para><literal>INCLUDING ALL</literal> is an abbreviated form of
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<literal>INCLUDING DEFAULTS INCLUDING CONSTRAINTS INCLUDING INDEXES INCLUDING STORAGE INCLUDING COMMENTS</literal>.
</para>
Note also that unlike <literal>INHERITS</literal>, columns and
constraints copied by <literal>LIKE</> are not merged with similarly
named columns and constraints.
If the same name is specified explicitly or in another
<literal>LIKE</literal> clause, an error is signalled.
<para>
The <literal>LIKE</literal> clause can also be used to copy columns from
views, foreign tables, or composite types. Inapplicable options (e.g., <literal>INCLUDING
INDEXES</literal> from a view) are ignored.
</para>
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<term><literal>CONSTRAINT <replaceable class="PARAMETER">constraint_name</replaceable></literal></term>
<listitem>
<para>
An optional name for a column or table constraint. If the
constraint is violated, the constraint name is present in error messages,
so constraint names like <literal>col must be positive</> can be used
to communicate helpful constraint information to client applications.
(Double-quotes are needed to specify constraint names that contain spaces.)
If a constraint name is not specified, the system generates a name.
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</para>
</listitem>
</varlistentry>
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<varlistentry>
<term><literal>NOT NULL</></term>
<listitem>
<para>
The column is not allowed to contain null values.
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</para>
</listitem>
</varlistentry>
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<varlistentry>
<term><literal>NULL</></term>
<listitem>
<para>
The column is allowed to contain null values. This is the default.
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</para>
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<para>
This clause is only provided for compatibility with
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non-standard SQL databases. Its use is discouraged in new
applications.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>CHECK ( <replaceable class="PARAMETER">expression</replaceable> ) [ NO INHERIT ] </literal></term>
<listitem>
<para>
The <literal>CHECK</> clause specifies an expression producing a
Boolean result which new or updated rows must satisfy for an
insert or update operation to succeed. Expressions evaluating
to TRUE or UNKNOWN succeed. Should any row of an insert or
update operation produce a FALSE result an error exception is
raised and the insert or update does not alter the database. A
check constraint specified as a column constraint should
reference that column's value only, while an expression
appearing in a table constraint can reference multiple columns.
</para>
<para>
Currently, <literal>CHECK</literal> expressions cannot contain
subqueries nor refer to variables other than columns of the
current row.
</para>
<para>
A constraint marked with <literal>NO INHERIT</> will not propagate to
</listitem>
</varlistentry>
<varlistentry>
<term><literal>DEFAULT
<replaceable>default_expr</replaceable></literal></term>
<listitem>
<para>
The <literal>DEFAULT</> clause assigns a default data value for
the column whose column definition it appears within. The value
is any variable-free expression (subqueries and cross-references
to other columns in the current table are not allowed). The
data type of the default expression must match the data type of the
column.
</para>
<para>
The default expression will be used in any insert operation that
does not specify a value for the column. If there is no default
for a column, then the default is null.
</para>
</listitem>
</varlistentry>
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<varlistentry>
<term><literal>UNIQUE</> (column constraint)</term>
<term><literal>UNIQUE ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] )</> (table constraint)</term>
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<listitem>
<para>
The <literal>UNIQUE</literal> constraint specifies that a
group of one or more columns of a table can contain
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only unique values. The behavior of the unique table constraint
is the same as that for column constraints, with the additional
capability to span multiple columns.
</para>
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<para>
For the purpose of a unique constraint, null values are not
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considered equal.
</para>
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<para>
Each unique table constraint must name a set of columns that is
different from the set of columns named by any other unique or
primary key constraint defined for the table. (Otherwise it
would just be the same constraint listed twice.)
</para>
</listitem>
</varlistentry>
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<varlistentry>
<term><literal>PRIMARY KEY</> (column constraint)</term>
<term><literal>PRIMARY KEY ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] )</> (table constraint)</term>
<listitem>
<para>
The <literal>PRIMARY KEY</> constraint specifies that a column or
columns of a table can contain only unique (non-duplicate), nonnull
values. Only one primary key can be specified for a table, whether as a
column constraint or a table constraint.
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</para>
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<para>
The primary key constraint should name a set of columns that is
different from the set of columns named by any unique
constraint defined for the same table. (Otherwise, the unique
constraint is redundant and will be discarded.)
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</para>
<literal>PRIMARY KEY</literal> enforces the same data constraints as
a combination of <literal>UNIQUE</> and <literal>NOT NULL</>, but
identifying a set of columns as the primary key also provides metadata
about the design of the schema, since a primary key implies that other
tables can rely on this set of columns as a unique identifier for rows.
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</listitem>
</varlistentry>
<varlistentry id="SQL-CREATETABLE-EXCLUDE">
<term><literal>EXCLUDE [ USING <replaceable class="parameter">index_method</replaceable> ] ( <replaceable class="parameter">exclude_element</replaceable> WITH <replaceable class="parameter">operator</replaceable> [, ... ] ) <replaceable class="parameter">index_parameters</replaceable> [ WHERE ( <replaceable class="parameter">predicate</replaceable> ) ]</literal></term>
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<listitem>
<para>
The <literal>EXCLUDE</> clause defines an exclusion
constraint, which guarantees that if
any two rows are compared on the specified column(s) or
expression(s) using the specified operator(s), not all of these
comparisons will return <literal>TRUE</>. If all of the
specified operators test for equality, this is equivalent to a
<literal>UNIQUE</> constraint, although an ordinary unique constraint
will be faster. However, exclusion constraints can specify
constraints that are more general than simple equality.
For example, you can specify a constraint that
no two rows in the table contain overlapping circles
(see <xref linkend="datatype-geometric">) by using the
<literal>&&</> operator.
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</para>
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<para>
Exclusion constraints are implemented using
an index, so each specified operator must be associated with an
appropriate operator class
(see <xref linkend="indexes-opclass">) for the index access
method <replaceable>index_method</>.
The operators are required to be commutative.
Each <replaceable class="parameter">exclude_element</replaceable>
can optionally specify an operator class and/or ordering options;
these are described fully under
<xref linkend="sql-createindex">.
</para>
<para>
The access method must support <literal>amgettuple</> (see <xref
linkend="indexam">); at present this means <acronym>GIN</>
cannot be used. Although it's allowed, there is little point in using
B-tree or hash indexes with an exclusion constraint, because this
does nothing that an ordinary unique constraint doesn't do better.
So in practice the access method will always be <acronym>GiST</> or
<acronym>SP-GiST</>.
</para>
<para>
The <replaceable class="parameter">predicate</> allows you to specify an
exclusion constraint on a subset of the table; internally this creates a
partial index. Note that parentheses are required around the predicate.
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</para>
</listitem>
</varlistentry>
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<varlistentry>
<term><literal>REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH <replaceable class="parameter">matchtype</replaceable> ] [ ON DELETE <replaceable class="parameter">action</replaceable> ] [ ON UPDATE <replaceable class="parameter">action</replaceable> ]</literal> (column constraint)</term>
<term><literal>FOREIGN KEY ( <replaceable class="parameter">column_name</replaceable> [, ... ] )
REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> [, ... ] ) ]
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[ MATCH <replaceable class="parameter">matchtype</replaceable> ]
[ ON DELETE <replaceable class="parameter">action</replaceable> ]
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[ ON UPDATE <replaceable class="parameter">action</replaceable> ]</literal>
(table constraint)</term>
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<listitem>
<para>
These clauses specify a foreign key constraint, which requires
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that a group of one or more columns of the new table must only
contain values that match values in the referenced
column(s) of some row of the referenced table. If <replaceable
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class="parameter">refcolumn</replaceable> is omitted, the
primary key of the <replaceable class="parameter">reftable</replaceable>
is used. The referenced columns must be the columns of a non-deferrable
unique or primary key constraint in the referenced table. Note that
foreign key constraints cannot be defined between temporary tables and
permanent tables.
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</para>
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<para>
A value inserted into the referencing column(s) is matched against the
values of the referenced table and referenced columns using the
given match type. There are three match types: <literal>MATCH
FULL</>, <literal>MATCH PARTIAL</>, and <literal>MATCH
SIMPLE</literal>, which is also the default. <literal>MATCH
FULL</> will not allow one column of a multicolumn foreign key
to be null unless all foreign key columns are null.
<literal>MATCH SIMPLE</literal> allows some foreign key columns
to be null while other parts of the foreign key are not
null. <literal>MATCH PARTIAL</> is not yet implemented.
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</para>
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<para>
In addition, when the data in the referenced columns is changed,
certain actions are performed on the data in this table's
columns. The <literal>ON DELETE</literal> clause specifies the
action to perform when a referenced row in the referenced table is
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being deleted. Likewise, the <literal>ON UPDATE</literal>
clause specifies the action to perform when a referenced column
in the referenced table is being updated to a new value. If the
row is updated, but the referenced column is not actually
changed, no action is done. Referential actions other than the
<literal>NO ACTION</literal> check cannot be deferred, even if
the constraint is declared deferrable. There are the following possible
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actions for each clause:
<variablelist>
<varlistentry>
<term><literal>NO ACTION</literal></term>
<listitem>
<para>
Produce an error indicating that the deletion or update
would create a foreign key constraint violation.
If the constraint is deferred, this
error will be produced at constraint check time if there still
exist any referencing rows. This is the default action.
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</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>RESTRICT</literal></term>
<listitem>
<para>
Produce an error indicating that the deletion or update
would create a foreign key constraint violation.
This is the same as <literal>NO ACTION</literal> except that
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</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>CASCADE</literal></term>
<listitem>
<para>
Delete any rows referencing the deleted row, or update the
value of the referencing column to the new value of the
referenced column, respectively.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>SET NULL</literal></term>
<listitem>
<para>
Set the referencing column(s) to null.
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</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>SET DEFAULT</literal></term>
<listitem>
<para>
Set the referencing column(s) to their default values.
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</para>
</listitem>
</varlistentry>
</variablelist>
</para>
<para>
If the referenced column(s) are changed frequently, it might be wise to
add an index to the foreign key column so that referential actions
associated with the foreign key column can be performed more
efficiently.
</para>
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</listitem>
</varlistentry>
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<varlistentry>
<term><literal>DEFERRABLE</literal></term>
<term><literal>NOT DEFERRABLE</literal></term>
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<listitem>
<para>
This controls whether the constraint can be deferred. A
constraint that is not deferrable will be checked immediately
after every command. Checking of constraints that are
deferrable can be postponed until the end of the transaction
(using the <xref linkend="sql-set-constraints"> command).
<literal>NOT DEFERRABLE</literal> is the default.
Currently, only <literal>UNIQUE</>, <literal>PRIMARY KEY</>,
<literal>EXCLUDE</>, and
<literal>REFERENCES</> (foreign key) constraints accept this
clause. <literal>NOT NULL</> and <literal>CHECK</> constraints are not
deferrable.
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</para>
</listitem>
</varlistentry>
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<varlistentry>
<term><literal>INITIALLY IMMEDIATE</literal></term>
<term><literal>INITIALLY DEFERRED</literal></term>
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<listitem>
<para>
If a constraint is deferrable, this clause specifies the default
time to check the constraint. If the constraint is
<literal>INITIALLY IMMEDIATE</literal>, it is checked after each
statement. This is the default. If the constraint is
<literal>INITIALLY DEFERRED</literal>, it is checked only at the
end of the transaction. The constraint check time can be
altered with the <xref linkend="sql-set-constraints"> command.
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</para>
</listitem>
</varlistentry>
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<varlistentry>
<term><literal>WITH ( <replaceable class="PARAMETER">storage_parameter</replaceable> [= <replaceable class="PARAMETER">value</replaceable>] [, ... ] )</literal></term>
<listitem>
<para>
This clause specifies optional storage parameters for a table or index;
see <xref linkend="sql-createtable-storage-parameters"
endterm="sql-createtable-storage-parameters-title"> for more
information. The <literal>WITH</> clause for a
table can also include <literal>OIDS=TRUE</> (or just <literal>OIDS</>)
to specify that rows of the new table
should have OIDs (object identifiers) assigned to them, or
<literal>OIDS=FALSE</> to specify that the rows should not have OIDs.
If <literal>OIDS</> is not specified, the default setting depends upon
the <xref linkend="guc-default-with-oids"> configuration parameter.
(If the new table inherits from any tables that have OIDs, then
<literal>OIDS=TRUE</> is forced even if the command says
<literal>OIDS=FALSE</>.)
</para>
<para>
If <literal>OIDS=FALSE</literal> is specified or implied, the new
table does not store OIDs and no OID will be assigned for a row inserted
into it. This is generally considered worthwhile, since it
will reduce OID consumption and thereby postpone the wraparound
of the 32-bit OID counter. Once the counter wraps around, OIDs
can no longer be assumed to be unique, which makes them
considerably less useful. In addition, excluding OIDs from a
table reduces the space required to store the table on disk by
4 bytes per row (on most machines), slightly improving performance.
</para>
<para>
To remove OIDs from a table after it has been created, use <xref
linkend="sql-altertable">.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>WITH OIDS</></term>
<term><literal>WITHOUT OIDS</></term>
<listitem>
<para>
These are obsolescent syntaxes equivalent to <literal>WITH (OIDS)</>
and <literal>WITH (OIDS=FALSE)</>, respectively. If you wish to give
both an <literal>OIDS</> setting and storage parameters, you must use
the <literal>WITH ( ... )</> syntax; see above.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>ON COMMIT</literal></term>
<listitem>
<para>
The behavior of temporary tables at the end of a transaction
block can be controlled using <literal>ON COMMIT</literal>.
The three options are:
<variablelist>
<varlistentry>
<term><literal>PRESERVE ROWS</literal></term>
<listitem>
<para>
No special action is taken at the ends of transactions.
This is the default behavior.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>DELETE ROWS</literal></term>
<listitem>
<para>
All rows in the temporary table will be deleted at the end
of each transaction block. Essentially, an automatic <xref
linkend="sql-truncate"> is done
at each commit.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>DROP</literal></term>
<listitem>
<para>
The temporary table will be dropped at the end of the current
transaction block.
</para>
</listitem>
</varlistentry>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>TABLESPACE <replaceable class="PARAMETER">tablespace_name</replaceable></literal></term>
<listitem>
<para>
The <replaceable class="PARAMETER">tablespace_name</replaceable> is the name
of the tablespace in which the new table is to be created.
If not specified,
<xref linkend="guc-default-tablespace"> is consulted, or
<xref linkend="guc-temp-tablespaces"> if the table is temporary.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>USING INDEX TABLESPACE <replaceable class="PARAMETER">tablespace_name</replaceable></literal></term>
<listitem>
<para>
This clause allows selection of the tablespace in which the index
associated with a <literal>UNIQUE</literal>, <literal>PRIMARY
KEY</literal>, or <literal>EXCLUDE</> constraint will be created.
If not specified,
<xref linkend="guc-default-tablespace"> is consulted, or
<xref linkend="guc-temp-tablespaces"> if the table is temporary.
</para>
</listitem>
</varlistentry>
</variablelist>
<refsect2 id="SQL-CREATETABLE-storage-parameters">
<title id="SQL-CREATETABLE-storage-parameters-title">Storage Parameters</title>
<indexterm zone="sql-createtable-storage-parameters">
<primary>storage parameters</primary>
</indexterm>
<para>
The <literal>WITH</> clause can specify <firstterm>storage parameters</>
for tables, and for indexes associated with a <literal>UNIQUE</literal>,
<literal>PRIMARY KEY</literal>, or <literal>EXCLUDE</> constraint.
Storage parameters for
indexes are documented in <xref linkend="SQL-CREATEINDEX">.
The storage parameters currently
available for tables are listed below. For each parameter, unless noted,
there is an additional parameter with the same name prefixed with
<literal>toast.</literal>, which can be used to control the behavior of the
table's secondary <acronym>TOAST</> table, if any
(see <xref linkend="storage-toast"> for more information about TOAST).
Note that the TOAST table inherits the
<literal>autovacuum_*</literal> values from its parent table, if there are
no <literal>toast.autovacuum_*</literal> settings set.
</para>
<variablelist>
<varlistentry>
<term><literal>fillfactor</> (<type>integer</>)</term>
<listitem>
<para>
The fillfactor for a table is a percentage between 10 and 100.
100 (complete packing) is the default. When a smaller fillfactor
is specified, <command>INSERT</> operations pack table pages only
to the indicated percentage; the remaining space on each page is
reserved for updating rows on that page. This gives <command>UPDATE</>
a chance to place the updated copy of a row on the same page as the
original, which is more efficient than placing it on a different page.
For a table whose entries are never updated, complete packing is the
best choice, but in heavily updated tables smaller fillfactors are
appropriate. This parameter cannot be set for TOAST tables.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>autovacuum_enabled</>, <literal>toast.autovacuum_enabled</literal> (<type>boolean</>)</term>
<listitem>
<para>
Enables or disables the autovacuum daemon on a particular table.
If true, the autovacuum daemon will initiate a <command>VACUUM</> operation
on a particular table when the number of updated or deleted tuples exceeds
<literal>autovacuum_vacuum_threshold</> plus
<literal>autovacuum_vacuum_scale_factor</> times the number of live tuples
currently estimated to be in the relation.
Similarly, it will initiate an <command>ANALYZE</> operation when the
number of inserted, updated or deleted tuples exceeds
<literal>autovacuum_analyze_threshold</> plus
<literal>autovacuum_analyze_scale_factor</> times the number of live tuples
currently estimated to be in the relation.
If false, this table will not be autovacuumed, except to prevent
transaction Id wraparound. See <xref linkend="vacuum-for-wraparound"> for
more about wraparound prevention.
Observe that this variable inherits its value from the <xref
linkend="guc-autovacuum"> setting.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>autovacuum_vacuum_threshold</>, <literal>toast.autovacuum_vacuum_threshold</literal> (<type>integer</>)</term>
<listitem>
<para>
Minimum number of updated or deleted tuples before initiate a
<command>VACUUM</> operation on a particular table.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>autovacuum_vacuum_scale_factor</>, <literal>toast.autovacuum_vacuum_scale_factor</literal> (<type>float4</>)</term>
<listitem>
<para>
Multiplier for <structfield>reltuples</> to add to
<literal>autovacuum_vacuum_threshold</>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>autovacuum_analyze_threshold</> (<type>integer</>)</term>
<listitem>
<para>
Minimum number of inserted, updated, or deleted tuples before initiate an
<command>ANALYZE</> operation on a particular table.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>autovacuum_analyze_scale_factor</> (<type>float4</>)</term>
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<listitem>
<para>
Multiplier for <structfield>reltuples</> to add to
<literal>autovacuum_analyze_threshold</>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>autovacuum_vacuum_cost_delay</>, <literal>toast.autovacuum_vacuum_cost_delay</literal> (<type>integer</>)</term>
<listitem>
<para>
Custom <xref linkend="guc-autovacuum-vacuum-cost-delay"> parameter.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>autovacuum_vacuum_cost_limit</>, <literal>toast.autovacuum_vacuum_cost_limit</literal> (<type>integer</>)</term>
<listitem>
<para>
Custom <xref linkend="guc-autovacuum-vacuum-cost-limit"> parameter.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>autovacuum_freeze_min_age</>, <literal>toast.autovacuum_freeze_min_age</literal> (<type>integer</>)</term>
<listitem>
<para>
Custom <xref linkend="guc-vacuum-freeze-min-age"> parameter. Note that
autovacuum will ignore attempts to set a per-table
<literal>autovacuum_freeze_min_age</> larger than the half system-wide
<xref linkend="guc-autovacuum-freeze-max-age"> setting.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>autovacuum_freeze_max_age</>, <literal>toast.autovacuum_freeze_max_age</literal> (<type>integer</>)</term>
<listitem>
<para>
Custom <xref linkend="guc-autovacuum-freeze-max-age"> parameter. Note that
autovacuum will ignore attempts to set a per-table
<literal>autovacuum_freeze_max_age</> larger than the system-wide setting
(it can only be set smaller).
</para>
</listitem>
</varlistentry>
<varlistentry>