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Postgres documentation

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CREATE [ TEMPORARY | TEMP ] TABLE <replaceable class="PARAMETER">table_name</replaceable> (

{ <replaceable class="PARAMETER">column_name</replaceable> <replaceable class="PARAMETER">type</replaceable> [ <replaceable class="PARAMETER">column_constraint</replaceable> [ ... ] ]

| <replaceable>table_constraint</replaceable> } [, ... ]

) [ INHERITS ( <replaceable>inherited_table</replaceable> [, ... ] ) ]

) [ INHERITS ( <replaceable>parent_table</replaceable> [, ... ] ) ]

where <replaceable class="PARAMETER">column_constraint</replaceable> can be:

[ CONSTRAINT <replaceable class="PARAMETER">constraint_name</replaceable> ]

</varlistentry>

<varlistentry>

<term><replaceable class="PARAMETER">inherited_table</replaceable></term>

<term><replaceable class="PARAMETER">parent_table</replaceable></term>

<listitem>

<para>

The optional INHERITS clause specifies a list of table

names from which this table automatically inherits all fields.

If any inherited field name appears more than once,

<productname>Postgres</productname>

reports an error.

<productname>Postgres</productname> automatically allows the created

table to inherit functions on tables above it in the inheritance

hierarchy.

</para>

</listitem>

</varlistentry>

existing datatype.

</para>

<para>

A table can have no more than 1600 columns (in practice, the

effective limit is lower because of tuple-length constraints).

A table cannot have the same name as a system catalog table.

</para>

</refsect1>

<refsect1 id="R1-SQL-INHERITSCLAUSE-1">

<title id="R1-SQL-INHERITSCLAUSE-1-TITLE">

INHERITS Clause

</title>

<para>

<synopsis>

INHERITS ( <replaceable class="PARAMETER">parent_table</replaceable> [, ... ] )

</synopsis>

</para>

<para>

The optional INHERITS

clause specifies a collection of table names from which this table

automatically inherits all fields. If any inherited field name

appears more than once, Postgres reports an error. Postgres automatically

allows the created table to inherit functions on tables above it in

the inheritance hierarchy. Inheritance of functions is done according

to the conventions of the Common Lisp Object System (CLOS).

clause specifies a list of table names from which the new table

automatically inherits all fields. If the same field name appears in

more than one parent table, Postgres reports an error unless the field

definitions match in each of the parent tables. If there is no

definition conflict, then the duplicate fields are merged to form a single

field of the new table. If the new table's own field list contains a

field name that is also inherited, this declaration must likewise match

the inherited field(s), and the field definitions are merged into one.

</para>

<para>

A table can have no more than 1600 columns (in practice, the

effective limit is lower because of tuple-length constraints).

A table cannot have the same name as a system catalog table.

Inherited and new field declarations of the same name must specify exactly

the same data type to avoid an error. They need not specify identical

constraints --- all constraints provided from any declaration are merged

together and all are applied to the new table. If the new table explicitly

specifies a default value for the field, this default overrides any

defaults from inherited declarations of the field. Otherwise, any parents

that specify default values for the field must all specify the same

default, or an error will be reported.

</para>

<para>

Postgres automatically allows the created table to inherit functions on

tables above it in the inheritance hierarchy; that is, if we create table

<literal>foo</literal> inheriting from <literal>bar</literal>, then

functions that accept the tuple type <literal>bar</literal> can also be

applied to instances of <literal>foo</literal>. (Currently, this works

reliably for functions on the first or only parent table, but not so well

for functions on additional parents.)

</para>

</refsect1>