diff options
Diffstat (limited to 'doc/src/sgml/ref/create_foreign_data_wrapper.sgml')
| -rw-r--r-- | doc/src/sgml/ref/create_foreign_data_wrapper.sgml | 50 |
1 files changed, 35 insertions, 15 deletions
diff --git a/doc/src/sgml/ref/create_foreign_data_wrapper.sgml b/doc/src/sgml/ref/create_foreign_data_wrapper.sgml index f626d56665b..711f32b118b 100644 --- a/doc/src/sgml/ref/create_foreign_data_wrapper.sgml +++ b/doc/src/sgml/ref/create_foreign_data_wrapper.sgml @@ -22,7 +22,8 @@ PostgreSQL documentation <refsynopsisdiv> <synopsis> CREATE FOREIGN DATA WRAPPER <replaceable class="parameter">name</replaceable> - [ VALIDATOR <replaceable class="parameter">valfunction</replaceable> | NO VALIDATOR ] + [ HANDLER <replaceable class="parameter">handler_function</replaceable> | NO HANDLER ] + [ VALIDATOR <replaceable class="parameter">validator_function</replaceable> | NO VALIDATOR ] [ OPTIONS ( <replaceable class="PARAMETER">option</replaceable> '<replaceable class="PARAMETER">value</replaceable>' [, ... ] ) ] </synopsis> </refsynopsisdiv> @@ -59,13 +60,32 @@ CREATE FOREIGN DATA WRAPPER <replaceable class="parameter">name</replaceable> </varlistentry> <varlistentry> - <term><literal>VALIDATOR <replaceable class="parameter">valfunction</replaceable></literal></term> + <term><literal>HANDLER <replaceable class="parameter">handler_function</replaceable></literal></term> <listitem> <para> - <replaceable class="parameter">valfunction</replaceable> is the + <replaceable class="parameter">handler_function</replaceable> is the + name of a previously registered function that will be called to + retrieve the execution functions for foreign tables. + The handler function must take no arguments, and + its return type must be <type>fdw_handler</type>. + </para> + + <para> + It is possible to create a foreign-data wrapper with no handler + function, but foreign tables using such a wrapper can only be declared, + not accessed. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><literal>VALIDATOR <replaceable class="parameter">validator_function</replaceable></literal></term> + <listitem> + <para> + <replaceable class="parameter">validator_function</replaceable> is the name of a previously registered function that will be called to check the generic options given to the foreign-data wrapper, as - well as to foreign servers and user mappings using the + well as options for foreign servers and user mappings using the foreign-data wrapper. If no validator function or <literal>NO VALIDATOR</literal> is specified, then options will not be checked at creation time. (Foreign-data wrappers will possibly @@ -75,8 +95,8 @@ CREATE FOREIGN DATA WRAPPER <replaceable class="parameter">name</replaceable> contain the array of options as stored in the system catalogs, and one of type <type>oid</type>, which will be the OID of the system catalog containing the options. The return type is ignored; - the function should indicate invalid options using the - <function>ereport()</function> function. + the function should report invalid options using the + <function>ereport(ERROR)</function> function. </para> </listitem> </varlistentry> @@ -87,8 +107,8 @@ CREATE FOREIGN DATA WRAPPER <replaceable class="parameter">name</replaceable> <para> This clause specifies options for the new foreign-data wrapper. The allowed option names and values are specific to each foreign - data wrapper and are validated using the foreign-data wrapper - library. Option names must be unique. + data wrapper and are validated using the foreign-data wrapper's + validator function. Option names must be unique. </para> </listitem> </varlistentry> @@ -122,17 +142,17 @@ CREATE FOREIGN DATA WRAPPER <replaceable class="parameter">name</replaceable> <title>Examples</title> <para> - Create a foreign-data wrapper <literal>dummy</>: + Create a useless foreign-data wrapper <literal>dummy</>: <programlisting> CREATE FOREIGN DATA WRAPPER dummy; </programlisting> </para> <para> - Create a foreign-data wrapper <literal>postgresql</> with - validator function <literal>postgresql_fdw_validator</>: + Create a foreign-data wrapper <literal>file</> with + handler function <literal>file_fdw_handler</>: <programlisting> -CREATE FOREIGN DATA WRAPPER postgresql VALIDATOR postgresql_fdw_validator; +CREATE FOREIGN DATA WRAPPER file HANDLER file_fdw_handler; </programlisting> </para> @@ -151,10 +171,10 @@ CREATE FOREIGN DATA WRAPPER mywrapper <para> <command>CREATE FOREIGN DATA WRAPPER</command> conforms to ISO/IEC - 9075-9 (SQL/MED), with the exception that - the <literal>VALIDATOR</literal> clause is an extension and the + 9075-9 (SQL/MED), with the exception that the <literal>HANDLER</literal> + and <literal>VALIDATOR</literal> clauses are extensions and the standard clauses <literal>LIBRARY</literal> and <literal>LANGUAGE</literal> - are not yet implemented in PostgreSQL. + are not implemented in PostgreSQL. </para> <para> |