diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/func.sgml | 24 | ||||
| -rw-r--r-- | doc/src/sgml/xfunc.sgml | 11 |
2 files changed, 29 insertions, 6 deletions
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml index 35c7f75eab2..e9dbcb9f8a0 100644 --- a/doc/src/sgml/func.sgml +++ b/doc/src/sgml/func.sgml @@ -1394,7 +1394,8 @@ </entry> <entry><type>text</type></entry> <entry> - Concatenate all arguments. NULL arguments are ignored. + Concatenate the text representations of all the arguments. + NULL arguments are ignored. </entry> <entry><literal>concat('abcde', 2, NULL, 22)</literal></entry> <entry><literal>abcde222</literal></entry> @@ -1411,8 +1412,8 @@ </entry> <entry><type>text</type></entry> <entry> - Concatenate all but first arguments with separators. The first - parameter is used as a separator. NULL arguments are ignored. + Concatenate all but the first argument with separators. The first + argument is used as the separator string. NULL arguments are ignored. </entry> <entry><literal>concat_ws(',', 'abcde', 2, NULL, 22)</literal></entry> <entry><literal>abcde,2,22</literal></entry> @@ -1522,8 +1523,9 @@ </entry> <entry><type>text</type></entry> <entry> - Format a string. This function is similar to the C function - <function>sprintf</>; but only the following conversion specifications + Format arguments according to a format string. + This function is similar to the C function + <function>sprintf</>, but only the following conversion specifications are recognized: <literal>%s</literal> interpolates the corresponding argument as a string; <literal>%I</literal> escapes its argument as an SQL identifier; <literal>%L</literal> escapes its argument as an @@ -2034,6 +2036,18 @@ </table> <para> + The <function>concat</function>, <function>concat_ws</function> and + <function>format</function> functions are variadic, so it is possible to + pass the values to be concatenated or formatted as an array marked with + the <literal>VARIADIC</literal> keyword (see <xref + linkend="xfunc-sql-variadic-functions">). The array's elements are + treated as if they were separate ordinary arguments to the function. + If the variadic array argument is NULL, <function>concat</function> + and <function>concat_ws</function> return NULL, but + <function>format</function> treats a NULL as a zero-element array. + </para> + + <para> See also the aggregate function <function>string_agg</function> in <xref linkend="functions-aggregate">. </para> diff --git a/doc/src/sgml/xfunc.sgml b/doc/src/sgml/xfunc.sgml index 85539feb0d2..4fb42842c6f 100644 --- a/doc/src/sgml/xfunc.sgml +++ b/doc/src/sgml/xfunc.sgml @@ -3153,6 +3153,10 @@ CREATE OR REPLACE FUNCTION retcomposite(IN integer, IN integer, <literal>fcinfo->flinfo</>. The parameter <literal>argnum</> is zero based. <function>get_call_result_type</> can also be used as an alternative to <function>get_fn_expr_rettype</>. + There is also <function>get_fn_expr_variadic</>, which can be used to + find out whether the call contained an explicit <literal>VARIADIC</> + keyword. This is primarily useful for <literal>VARIADIC "any"</> + functions, as described below. </para> <para> @@ -3229,7 +3233,12 @@ CREATE FUNCTION make_array(anyelement) RETURNS anyarray as happens with normal variadic functions; they will just be passed to the function separately. The <function>PG_NARGS()</> macro and the methods described above must be used to determine the number of actual - arguments and their types when using this feature. + arguments and their types when using this feature. Also, users of such + a function might wish to use the <literal>VARIADIC</> keyword in their + function call, with the expectation that the function would treat the + array elements as separate arguments. The function itself must implement + that behavior if wanted, after using <function>get_fn_expr_variadic</> to + detect that the actual argument was marked with <literal>VARIADIC</>. </para> </sect2> |