557 lines
20 KiB
Plaintext
557 lines
20 KiB
Plaintext
<!--
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doc/src/sgml/rel/alter_foreign_table.sgml
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PostgreSQL documentation
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-->
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<refentry id="sql-alterforeigntable">
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<indexterm zone="sql-alterforeigntable">
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<primary>ALTER FOREIGN TABLE</primary>
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</indexterm>
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<refmeta>
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<refentrytitle>ALTER FOREIGN TABLE</refentrytitle>
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<manvolnum>7</manvolnum>
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<refmiscinfo>SQL - Language Statements</refmiscinfo>
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</refmeta>
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<refnamediv>
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<refname>ALTER FOREIGN TABLE</refname>
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<refpurpose>change the definition of a foreign table</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<synopsis>
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ALTER FOREIGN TABLE [ IF EXISTS ] [ ONLY ] <replaceable class="parameter">name</replaceable> [ * ]
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<replaceable class="parameter">action</replaceable> [, ... ]
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ALTER FOREIGN TABLE [ IF EXISTS ] [ ONLY ] <replaceable class="parameter">name</replaceable> [ * ]
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RENAME [ COLUMN ] <replaceable class="parameter">column_name</replaceable> TO <replaceable class="parameter">new_column_name</replaceable>
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ALTER FOREIGN TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
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RENAME TO <replaceable class="parameter">new_name</replaceable>
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ALTER FOREIGN TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
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SET SCHEMA <replaceable class="parameter">new_schema</replaceable>
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<phrase>where <replaceable class="parameter">action</replaceable> is one of:</phrase>
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ADD [ COLUMN ] <replaceable class="parameter">column_name</replaceable> <replaceable class="parameter">data_type</replaceable> [ COLLATE <replaceable class="parameter">collation</replaceable> ] [ <replaceable class="parameter">column_constraint</replaceable> [ ... ] ]
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DROP [ COLUMN ] [ IF EXISTS ] <replaceable class="parameter">column_name</replaceable> [ RESTRICT | CASCADE ]
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ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> [ SET DATA ] TYPE <replaceable class="parameter">data_type</replaceable> [ COLLATE <replaceable class="parameter">collation</replaceable> ]
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ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET DEFAULT <replaceable class="parameter">expression</replaceable>
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ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> DROP DEFAULT
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ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> { SET | DROP } NOT NULL
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ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STATISTICS <replaceable class="parameter">integer</replaceable>
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ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
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ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
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ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN | DEFAULT }
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ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> OPTIONS ( [ ADD | SET | DROP ] <replaceable class="parameter">option</replaceable> ['<replaceable class="parameter">value</replaceable>'] [, ... ])
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ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
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VALIDATE CONSTRAINT <replaceable class="parameter">constraint_name</replaceable>
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DROP CONSTRAINT [ IF EXISTS ] <replaceable class="parameter">constraint_name</replaceable> [ RESTRICT | CASCADE ]
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DISABLE TRIGGER [ <replaceable class="parameter">trigger_name</replaceable> | ALL | USER ]
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ENABLE TRIGGER [ <replaceable class="parameter">trigger_name</replaceable> | ALL | USER ]
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ENABLE REPLICA TRIGGER <replaceable class="parameter">trigger_name</replaceable>
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ENABLE ALWAYS TRIGGER <replaceable class="parameter">trigger_name</replaceable>
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SET WITHOUT OIDS
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INHERIT <replaceable class="parameter">parent_table</replaceable>
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NO INHERIT <replaceable class="parameter">parent_table</replaceable>
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OWNER TO { <replaceable class="parameter">new_owner</replaceable> | CURRENT_ROLE | CURRENT_USER | SESSION_USER }
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OPTIONS ( [ ADD | SET | DROP ] <replaceable class="parameter">option</replaceable> ['<replaceable class="parameter">value</replaceable>'] [, ... ])
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</synopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para>
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<command>ALTER FOREIGN TABLE</command> changes the definition of an
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existing foreign table. There are several subforms:
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<variablelist>
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<varlistentry>
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<term><literal>ADD COLUMN</literal></term>
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<listitem>
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<para>
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This form adds a new column to the foreign table, using the same syntax as
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<link linkend="sql-createforeigntable"><command>CREATE FOREIGN TABLE</command></link>.
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Unlike the case when adding a column to a regular table, nothing happens
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to the underlying storage: this action simply declares that
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some new column is now accessible through the foreign table.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>DROP COLUMN [ IF EXISTS ]</literal></term>
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<listitem>
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<para>
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This form drops a column from a foreign table.
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You will need to say <literal>CASCADE</literal> if
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anything outside the table depends on the column; for example,
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views.
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If <literal>IF EXISTS</literal> is specified and the column
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does not exist, no error is thrown. In this case a notice
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is issued instead.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>SET DATA TYPE</literal></term>
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<listitem>
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<para>
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This form changes the type of a column of a foreign table.
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Again, this has no effect on any underlying storage: this action simply
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changes the type that <productname>PostgreSQL</productname> believes the column to
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have.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>SET</literal>/<literal>DROP DEFAULT</literal></term>
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<listitem>
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<para>
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These forms set or remove the default value for a column.
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Default values only apply in subsequent <command>INSERT</command>
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or <command>UPDATE</command> commands; they do not cause rows already in the
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table to change.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>SET</literal>/<literal>DROP NOT NULL</literal></term>
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<listitem>
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<para>
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Mark a column as allowing, or not allowing, null values.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>SET STATISTICS</literal></term>
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<listitem>
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<para>
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This form
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sets the per-column statistics-gathering target for subsequent
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<link linkend="sql-analyze"><command>ANALYZE</command></link> operations.
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See the similar form of <link linkend="sql-altertable"><command>ALTER TABLE</command></link>
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for more details.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )</literal></term>
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<term><literal>RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )</literal></term>
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<listitem>
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<para>
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This form sets or resets per-attribute options.
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See the similar form of <link linkend="sql-altertable"><command>ALTER TABLE</command></link>
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for more details.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<literal>SET STORAGE</literal>
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</term>
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<listitem>
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<para>
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This form sets the storage mode for a column.
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See the similar form of <link linkend="sql-altertable"><command>ALTER TABLE</command></link>
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for more details.
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Note that the storage mode has no effect unless the table's
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foreign-data wrapper chooses to pay attention to it.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]</literal></term>
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<listitem>
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<para>
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This form adds a new constraint to a foreign table, using the same
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syntax as <link linkend="sql-createforeigntable"><command>CREATE FOREIGN TABLE</command></link>.
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Currently only <literal>CHECK</literal> constraints are supported.
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</para>
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<para>
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Unlike the case when adding a constraint to a regular table, nothing is
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done to verify the constraint is correct; rather, this action simply
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declares that some new condition should be assumed to hold for all rows
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in the foreign table. (See the discussion
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in <link linkend="sql-createforeigntable"><command>CREATE FOREIGN TABLE</command></link>.)
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If the constraint is marked <literal>NOT VALID</literal>, then it isn't
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assumed to hold, but is only recorded for possible future use.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>VALIDATE CONSTRAINT</literal></term>
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<listitem>
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<para>
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This form marks as valid a constraint that was previously marked
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as <literal>NOT VALID</literal>. No action is taken to verify the
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constraint, but future queries will assume that it holds.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>DROP CONSTRAINT [ IF EXISTS ]</literal></term>
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<listitem>
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<para>
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This form drops the specified constraint on a foreign table.
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If <literal>IF EXISTS</literal> is specified and the constraint
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does not exist, no error is thrown.
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In this case a notice is issued instead.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>DISABLE</literal>/<literal>ENABLE [ REPLICA | ALWAYS ] TRIGGER</literal></term>
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<listitem>
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<para>
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These forms configure the firing of trigger(s) belonging to the foreign
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table. See the similar form of <link linkend="sql-altertable"><command>ALTER TABLE</command></link> for more
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details.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>SET WITHOUT OIDS</literal></term>
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<listitem>
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<para>
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Backward compatibility syntax for removing the <literal>oid</literal>
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system column. As <literal>oid</literal> system columns cannot be added
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anymore, this never has an effect.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>INHERIT <replaceable class="parameter">parent_table</replaceable></literal></term>
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<listitem>
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<para>
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This form adds the target foreign table as a new child of the specified
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parent table.
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See the similar form of <link linkend="sql-altertable"><command>ALTER TABLE</command></link>
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for more details.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>NO INHERIT <replaceable class="parameter">parent_table</replaceable></literal></term>
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<listitem>
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<para>
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This form removes the target foreign table from the list of children of
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the specified parent table.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>OWNER</literal></term>
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<listitem>
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<para>
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This form changes the owner of the foreign table to the
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specified user.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>OPTIONS ( [ ADD | SET | DROP ] <replaceable class="parameter">option</replaceable> ['<replaceable class="parameter">value</replaceable>'] [, ... ] )</literal></term>
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<listitem>
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<para>
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Change options for the foreign table or one of its columns.
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<literal>ADD</literal>, <literal>SET</literal>, and <literal>DROP</literal>
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specify the action to be performed. <literal>ADD</literal> is assumed
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if no operation is explicitly specified. Duplicate option names are not
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allowed (although it's OK for a table option and a column option to have
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the same name). Option names and values are also validated using the
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foreign data wrapper library.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>RENAME</literal></term>
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<listitem>
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<para>
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The <literal>RENAME</literal> forms change the name of a foreign table
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or the name of an individual column in a foreign table.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>SET SCHEMA</literal></term>
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<listitem>
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<para>
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This form moves the foreign table into another schema.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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<para>
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All the actions except <literal>RENAME</literal> and <literal>SET SCHEMA</literal>
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can be combined into
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a list of multiple alterations to apply in parallel. For example, it
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is possible to add several columns and/or alter the type of several
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columns in a single command.
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</para>
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<para>
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If the command is written as <literal>ALTER FOREIGN TABLE IF EXISTS ...</literal>
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and the foreign table does not exist, no error is thrown. A notice is
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issued in this case.
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</para>
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<para>
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You must own the table to use <command>ALTER FOREIGN TABLE</command>.
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To change the schema of a foreign table, you must also have
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<literal>CREATE</literal> privilege on the new schema.
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To alter the owner, you must be able to <literal>SET ROLE</literal> to the
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new owning role, and that role must have <literal>CREATE</literal> privilege
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on the table's schema. (These restrictions enforce that altering the owner
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doesn't do anything you couldn't do by dropping and recreating the table.
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However, a superuser can alter ownership of any table anyway.)
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To add a column or alter a column type, you must also
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have <literal>USAGE</literal> privilege on the data type.
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</para>
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</refsect1>
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<refsect1>
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<title>Parameters</title>
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<variablelist>
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<varlistentry>
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<term><replaceable class="parameter">name</replaceable></term>
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<listitem>
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<para>
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The name (possibly schema-qualified) of an existing foreign table to
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alter. If <literal>ONLY</literal> is specified before the table name, only
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that table is altered. If <literal>ONLY</literal> is not specified, the table
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and all its descendant tables (if any) are altered. Optionally,
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<literal>*</literal> can be specified after the table name to explicitly
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indicate that descendant tables are included.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">column_name</replaceable></term>
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<listitem>
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<para>
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Name of a new or existing column.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">new_column_name</replaceable></term>
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<listitem>
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<para>
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New name for an existing column.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">new_name</replaceable></term>
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<listitem>
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<para>
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New name for the table.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">data_type</replaceable></term>
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<listitem>
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<para>
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Data type of the new column, or new data type for an existing
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column.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">table_constraint</replaceable></term>
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<listitem>
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<para>
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New table constraint for the foreign table.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">constraint_name</replaceable></term>
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<listitem>
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<para>
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Name of an existing constraint to drop.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>CASCADE</literal></term>
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<listitem>
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<para>
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Automatically drop objects that depend on the dropped column
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or constraint (for example, views referencing the column),
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and in turn all objects that depend on those objects
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(see <xref linkend="ddl-depend"/>).
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>RESTRICT</literal></term>
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<listitem>
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<para>
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Refuse to drop the column or constraint if there are any dependent
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objects. This is the default behavior.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">trigger_name</replaceable></term>
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<listitem>
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<para>
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Name of a single trigger to disable or enable.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>ALL</literal></term>
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<listitem>
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<para>
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Disable or enable all triggers belonging to the foreign table. (This
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requires superuser privilege if any of the triggers are internally
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generated triggers. The core system does not add such triggers to
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foreign tables, but add-on code could do so.)
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>USER</literal></term>
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<listitem>
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<para>
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Disable or enable all triggers belonging to the foreign table except
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for internally generated triggers.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">parent_table</replaceable></term>
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<listitem>
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<para>
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A parent table to associate or de-associate with this foreign table.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">new_owner</replaceable></term>
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<listitem>
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<para>
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The user name of the new owner of the table.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">new_schema</replaceable></term>
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<listitem>
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<para>
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The name of the schema to which the table will be moved.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Notes</title>
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<para>
|
|
The key word <literal>COLUMN</literal> is noise and can be omitted.
|
|
</para>
|
|
|
|
<para>
|
|
Consistency with the foreign server is not checked when a column is added
|
|
or removed with <literal>ADD COLUMN</literal> or
|
|
<literal>DROP COLUMN</literal>, a <literal>NOT NULL</literal>
|
|
or <literal>CHECK</literal> constraint is added, or a column type is changed
|
|
with <literal>SET DATA TYPE</literal>. It is the user's responsibility to ensure
|
|
that the table definition matches the remote side.
|
|
</para>
|
|
|
|
<para>
|
|
Refer to <link linkend="sql-createforeigntable"><command>CREATE FOREIGN TABLE</command></link> for a further description of valid
|
|
parameters.
|
|
</para>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Examples</title>
|
|
|
|
<para>
|
|
To mark a column as not-null:
|
|
<programlisting>
|
|
ALTER FOREIGN TABLE distributors ALTER COLUMN street SET NOT NULL;
|
|
</programlisting>
|
|
</para>
|
|
|
|
<para>
|
|
To change options of a foreign table:
|
|
<programlisting>
|
|
ALTER FOREIGN TABLE myschema.distributors OPTIONS (ADD opt1 'value', SET opt2 'value2', DROP opt3);
|
|
</programlisting></para>
|
|
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Compatibility</title>
|
|
|
|
<para>
|
|
The forms <literal>ADD</literal>, <literal>DROP</literal>,
|
|
and <literal>SET DATA TYPE</literal>
|
|
conform with the SQL standard. The other forms are
|
|
<productname>PostgreSQL</productname> extensions of the SQL standard.
|
|
Also, the ability to specify more than one manipulation in a single
|
|
<command>ALTER FOREIGN TABLE</command> command is an extension.
|
|
</para>
|
|
|
|
<para>
|
|
<command>ALTER FOREIGN TABLE DROP COLUMN</command> 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.
|
|
</para>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>See Also</title>
|
|
|
|
<simplelist type="inline">
|
|
<member><xref linkend="sql-createforeigntable"/></member>
|
|
<member><xref linkend="sql-dropforeigntable"/></member>
|
|
</simplelist>
|
|
</refsect1>
|
|
</refentry>
|