diff options
Diffstat (limited to 'doc/src/sgml/ref/create_function.sgml')
| -rw-r--r-- | doc/src/sgml/ref/create_function.sgml | 24 |
1 files changed, 8 insertions, 16 deletions
diff --git a/doc/src/sgml/ref/create_function.sgml b/doc/src/sgml/ref/create_function.sgml index cd6ac69eb63..a617f965427 100644 --- a/doc/src/sgml/ref/create_function.sgml +++ b/doc/src/sgml/ref/create_function.sgml @@ -259,8 +259,7 @@ CREATE [ OR REPLACE ] FUNCTION <term><literal>WINDOW</literal></term> <listitem> - <para> - <literal>WINDOW</literal> indicates that the function is a + <para><literal>WINDOW</literal> indicates that the function is a <firstterm>window function</> rather than a plain function. This is currently only useful for functions written in C. The <literal>WINDOW</> attribute cannot be changed when @@ -282,8 +281,7 @@ CREATE [ OR REPLACE ] FUNCTION <literal>VOLATILE</literal> is the default assumption. </para> - <para> - <literal>IMMUTABLE</literal> indicates that the function + <para><literal>IMMUTABLE</literal> indicates that the function cannot modify the database and always returns the same result when given the same argument values; that is, it does not do database lookups or otherwise use information not @@ -292,8 +290,7 @@ CREATE [ OR REPLACE ] FUNCTION immediately replaced with the function value. </para> - <para> - <literal>STABLE</literal> indicates that the function + <para><literal>STABLE</literal> indicates that the function cannot modify the database, and that within a single table scan it will consistently return the same result for the same argument values, but that its @@ -306,8 +303,7 @@ CREATE [ OR REPLACE ] FUNCTION as stable, since their values do not change within a transaction. </para> - <para> - <literal>VOLATILE</literal> indicates that the function value can + <para><literal>VOLATILE</literal> indicates that the function value can change even within a single table scan, so no optimizations can be made. Relatively few database functions are volatile in this sense; some examples are <literal>random()</>, <literal>currval()</>, @@ -329,16 +325,14 @@ CREATE [ OR REPLACE ] FUNCTION <term><literal>STRICT</literal></term> <listitem> - <para> - <literal>CALLED ON NULL INPUT</literal> (the default) indicates + <para><literal>CALLED ON NULL INPUT</literal> (the default) indicates that the function will be called normally when some of its arguments are null. It is then the function author's responsibility to check for null values if necessary and respond appropriately. </para> - <para> - <literal>RETURNS NULL ON NULL INPUT</literal> or + <para><literal>RETURNS NULL ON NULL INPUT</literal> or <literal>STRICT</literal> indicates that the function always returns null whenever any of its arguments are null. If this parameter is specified, the function is not executed when there @@ -353,8 +347,7 @@ CREATE [ OR REPLACE ] FUNCTION <term><literal><optional>EXTERNAL</optional> SECURITY DEFINER</literal></term> <listitem> - <para> - <literal>SECURITY INVOKER</literal> indicates that the function + <para><literal>SECURITY INVOKER</literal> indicates that the function is to be executed with the privileges of the user that calls it. That is the default. <literal>SECURITY DEFINER</literal> specifies that the function is to be executed with the @@ -499,8 +492,7 @@ CREATE [ OR REPLACE ] FUNCTION <varlistentry> <term><literal>isCachable</></term> <listitem> - <para> - <literal>isCachable</literal> is an obsolete equivalent of + <para><literal>isCachable</literal> is an obsolete equivalent of <literal>IMMUTABLE</literal>; it's still accepted for backwards-compatibility reasons. </para> |