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><H1
><A
NAME="SQL-ALTERFOREIGNTABLE"
></A
>ALTER FOREIGN TABLE</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN65155"
></A
><H2
>Name</H2
>ALTER FOREIGN TABLE -- change the definition of a foreign table</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN65160"
></A
><H2
>Synopsis</H2
><PRE
CLASS="SYNOPSIS"
>ALTER FOREIGN TABLE [ IF EXISTS ] <TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
>
<TT
CLASS="REPLACEABLE"
><I
>action</I
></TT
> [, ... ]
ALTER FOREIGN TABLE [ IF EXISTS ] <TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
>
RENAME [ COLUMN ] <TT
CLASS="REPLACEABLE"
><I
>column_name</I
></TT
> TO <TT
CLASS="REPLACEABLE"
><I
>new_column_name</I
></TT
>
ALTER FOREIGN TABLE [ IF EXISTS ] <TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
>
RENAME TO <TT
CLASS="REPLACEABLE"
><I
>new_name</I
></TT
>
ALTER FOREIGN TABLE [ IF EXISTS ] <TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
>
SET SCHEMA <TT
CLASS="REPLACEABLE"
><I
>new_schema</I
></TT
>
<SPAN
CLASS="phrase"
><SPAN
CLASS="PHRASE"
>where <TT
CLASS="REPLACEABLE"
><I
>action</I
></TT
> is one of:</SPAN
></SPAN
>
ADD [ COLUMN ] <TT
CLASS="REPLACEABLE"
><I
>column_name</I
></TT
> <TT
CLASS="REPLACEABLE"
><I
>data_type</I
></TT
> [ COLLATE <TT
CLASS="REPLACEABLE"
><I
>collation</I
></TT
> ] [ <TT
CLASS="REPLACEABLE"
><I
>column_constraint</I
></TT
> [ ... ] ]
DROP [ COLUMN ] [ IF EXISTS ] <TT
CLASS="REPLACEABLE"
><I
>column_name</I
></TT
> [ RESTRICT | CASCADE ]
ALTER [ COLUMN ] <TT
CLASS="REPLACEABLE"
><I
>column_name</I
></TT
> [ SET DATA ] TYPE <TT
CLASS="REPLACEABLE"
><I
>data_type</I
></TT
>
ALTER [ COLUMN ] <TT
CLASS="REPLACEABLE"
><I
>column_name</I
></TT
> SET DEFAULT <TT
CLASS="REPLACEABLE"
><I
>expression</I
></TT
>
ALTER [ COLUMN ] <TT
CLASS="REPLACEABLE"
><I
>column_name</I
></TT
> DROP DEFAULT
ALTER [ COLUMN ] <TT
CLASS="REPLACEABLE"
><I
>column_name</I
></TT
> { SET | DROP } NOT NULL
ALTER [ COLUMN ] <TT
CLASS="REPLACEABLE"
><I
>column_name</I
></TT
> SET STATISTICS <TT
CLASS="REPLACEABLE"
><I
>integer</I
></TT
>
ALTER [ COLUMN ] <TT
CLASS="REPLACEABLE"
><I
>column_name</I
></TT
> SET ( <TT
CLASS="REPLACEABLE"
><I
>attribute_option</I
></TT
> = <TT
CLASS="REPLACEABLE"
><I
>value</I
></TT
> [, ... ] )
ALTER [ COLUMN ] <TT
CLASS="REPLACEABLE"
><I
>column_name</I
></TT
> RESET ( <TT
CLASS="REPLACEABLE"
><I
>attribute_option</I
></TT
> [, ... ] )
ALTER [ COLUMN ] <TT
CLASS="REPLACEABLE"
><I
>column_name</I
></TT
> OPTIONS ( [ ADD | SET | DROP ] <TT
CLASS="REPLACEABLE"
><I
>option</I
></TT
> ['<TT
CLASS="REPLACEABLE"
><I
>value</I
></TT
>'] [, ... ])
OWNER TO <TT
CLASS="REPLACEABLE"
><I
>new_owner</I
></TT
>
OPTIONS ( [ ADD | SET | DROP ] <TT
CLASS="REPLACEABLE"
><I
>option</I
></TT
> ['<TT
CLASS="REPLACEABLE"
><I
>value</I
></TT
>'] [, ... ])</PRE
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN65197"
></A
><H2
>Description</H2
><P
> <TT
CLASS="COMMAND"
>ALTER FOREIGN TABLE</TT
> changes the definition of an
existing foreign table. There are several subforms:
<P
></P
></P><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>ADD COLUMN</TT
></DT
><DD
><P
> This form adds a new column to the foreign table, using the same syntax as
<A
HREF="sql-createforeigntable.html"
>CREATE FOREIGN TABLE</A
>.
Unlike the case when adding a column to a regular table, nothing happens
to the underlying storage: this action simply declares that
some new column is now accessible through the foreign table.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>DROP COLUMN [ IF EXISTS ]</TT
></DT
><DD
><P
> This form drops a column from a foreign table.
You will need to say <TT
CLASS="LITERAL"
>CASCADE</TT
> if
anything outside the table depends on the column; for example,
views.
If <TT
CLASS="LITERAL"
>IF EXISTS</TT
> is specified and the column
does not exist, no error is thrown. In this case a notice
is issued instead.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>IF EXISTS</TT
></DT
><DD
><P
> Do not throw an error if the foreign table does not exist. A notice is
issued in this case.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>SET DATA TYPE</TT
></DT
><DD
><P
> This form changes the type of a column of a foreign table.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>SET</TT
>/<TT
CLASS="LITERAL"
>DROP DEFAULT</TT
></DT
><DD
><P
> These forms set or remove the default value for a column.
Default values only apply in subsequent <TT
CLASS="COMMAND"
>INSERT</TT
>
or <TT
CLASS="COMMAND"
>UPDATE</TT
> commands; they do not cause rows already in the
table to change.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>SET</TT
>/<TT
CLASS="LITERAL"
>DROP NOT NULL</TT
></DT
><DD
><P
> Mark a column as allowing, or not allowing, null values.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>SET STATISTICS</TT
></DT
><DD
><P
> This form
sets the per-column statistics-gathering target for subsequent
<A
HREF="sql-analyze.html"
>ANALYZE</A
> operations.
See the similar form of <A
HREF="sql-altertable.html"
>ALTER TABLE</A
>
for more details.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>SET ( <TT
CLASS="REPLACEABLE"
><I
>attribute_option</I
></TT
> = <TT
CLASS="REPLACEABLE"
><I
>value</I
></TT
> [, ... ] )</TT
><BR><TT
CLASS="LITERAL"
>RESET ( <TT
CLASS="REPLACEABLE"
><I
>attribute_option</I
></TT
> [, ... ] )</TT
></DT
><DD
><P
> This form sets or resets per-attribute options.
See the similar form of <A
HREF="sql-altertable.html"
>ALTER TABLE</A
>
for more details.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>OWNER</TT
></DT
><DD
><P
> This form changes the owner of the foreign table to the
specified user.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>RENAME</TT
></DT
><DD
><P
> The <TT
CLASS="LITERAL"
>RENAME</TT
> forms change the name of a foreign table
or the name of an individual column in a foreign table.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>SET SCHEMA</TT
></DT
><DD
><P
> This form moves the foreign table into another schema.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>OPTIONS ( [ ADD | SET | DROP ] <TT
CLASS="REPLACEABLE"
><I
>option</I
></TT
> ['<TT
CLASS="REPLACEABLE"
><I
>value</I
></TT
>'] [, ... ] )</TT
></DT
><DD
><P
> Change options for the foreign table or one of its columns.
<TT
CLASS="LITERAL"
>ADD</TT
>, <TT
CLASS="LITERAL"
>SET</TT
>, and <TT
CLASS="LITERAL"
>DROP</TT
>
specify the action to be performed. <TT
CLASS="LITERAL"
>ADD</TT
> is assumed
if no operation is explicitly specified. Duplicate option names are not
allowed (although it's OK for a table option and a column option to have
the same name). Option names and values are also validated using the
foreign data wrapper library.
</P
></DD
></DL
></DIV
><P>
</P
><P
> All the actions except <TT
CLASS="LITERAL"
>RENAME</TT
> and <TT
CLASS="LITERAL"
>SET SCHEMA</TT
>
can be combined into
a list of multiple alterations to apply in parallel. For example, it
is possible to add several columns and/or alter the type of several
columns in a single command.
</P
><P
> You must own the table to use <TT
CLASS="COMMAND"
>ALTER FOREIGN TABLE</TT
>.
To change the schema of a foreign table, you must also have
<TT
CLASS="LITERAL"
>CREATE</TT
> privilege on the new schema.
To alter the owner, you must also be a direct or indirect member of the new
owning role, and that role must have <TT
CLASS="LITERAL"
>CREATE</TT
> privilege on
the table's schema. (These restrictions enforce that altering the owner
doesn't do anything you couldn't do by dropping and recreating the table.
However, a superuser can alter ownership of any table anyway.)
To add a column or alter a column type, you must also
have <TT
CLASS="LITERAL"
>USAGE</TT
> privilege on the data type.
</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN65292"
></A
><H2
>Parameters</H2
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
></DT
><DD
><P
> The name (possibly schema-qualified) of an existing foreign table to
alter.
</P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>column_name</I
></TT
></DT
><DD
><P
> Name of a new or existing column.
</P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>new_column_name</I
></TT
></DT
><DD
><P
> New name for an existing column.
</P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>new_name</I
></TT
></DT
><DD
><P
> New name for the table.
</P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>data_type</I
></TT
></DT
><DD
><P
> Data type of the new column, or new data type for an existing
column.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>CASCADE</TT
></DT
><DD
><P
> Automatically drop objects that depend on the dropped column
(for example, views referencing the column).
</P
></DD
><DT
><TT
CLASS="LITERAL"
>RESTRICT</TT
></DT
><DD
><P
> Refuse to drop the column if there are any dependent
objects. This is the default behavior.
</P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>new_owner</I
></TT
></DT
><DD
><P
> The user name of the new owner of the table.
</P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>new_schema</I
></TT
></DT
><DD
><P
> The name of the schema to which the table will be moved.
</P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN65340"
></A
><H2
>Notes</H2
><P
> The key word <TT
CLASS="LITERAL"
>COLUMN</TT
> is noise and can be omitted.
</P
><P
> Consistency with the foreign server is not checked when a column is added
or removed with <TT
CLASS="LITERAL"
>ADD COLUMN</TT
> or
<TT
CLASS="LITERAL"
>DROP COLUMN</TT
>, a <TT
CLASS="LITERAL"
>NOT NULL</TT
> constraint is
added, or a column type is changed with <TT
CLASS="LITERAL"
>SET DATA TYPE</TT
>. It is
the user's responsibility to ensure that the table definition matches the
remote side.
</P
><P
> Refer to <A
HREF="sql-createforeigntable.html"
>CREATE FOREIGN TABLE</A
> for a further description of valid
parameters.
</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN65351"
></A
><H2
>Examples</H2
><P
> To mark a column as not-null:
</P><PRE
CLASS="PROGRAMLISTING"
>ALTER FOREIGN TABLE distributors ALTER COLUMN street SET NOT NULL;</PRE
><P>
</P
><P
> To change options of a foreign table:
</P><PRE
CLASS="PROGRAMLISTING"
>ALTER FOREIGN TABLE myschema.distributors OPTIONS (ADD opt1 'value', SET opt2, 'value2', DROP opt3 'value3');</PRE
><P></P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN65357"
></A
><H2
>Compatibility</H2
><P
> The forms <TT
CLASS="LITERAL"
>ADD</TT
>, <TT
CLASS="LITERAL"
>DROP</TT
>,
and <TT
CLASS="LITERAL"
>SET DATA TYPE</TT
>
conform with the SQL standard. The other forms are
<SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> extensions of the SQL standard.
Also, the ability to specify more than one manipulation in a single
<TT
CLASS="COMMAND"
>ALTER FOREIGN TABLE</TT
> command is an extension.
</P
><P
> <TT
CLASS="COMMAND"
>ALTER FOREIGN TABLE DROP COLUMN</TT
> can be used to drop the only
column of a foreign table, leaving a zero-column table. This is an
extension of SQL, which disallows zero-column foreign tables.
</P
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