*** a/doc/src/sgml/xfunc.sgml
--- b/doc/src/sgml/xfunc.sgml
***************
*** 153,159 **** SELECT clean_emp();
--- 153,186 ----
      (<literal>\</>) (assuming escape string syntax) in the body of
      the function (see <xref linkend="sql-syntax-strings">).
     </para>
+    
+    <sect2 id="xfunc-sql-function-parsing-mechanism">
+     <title>Parsing mechanism of a function</title>
  
+    <indexterm>
+     <primary>function</primary>
+     <secondary>parsing mechanism</secondary>
+    </indexterm>
+ 
+     <para>
+      The body of an SQL function is parsed as if it were a single - multi-part
+      statement and thus uses a constant snapshot of the system catalogs for
+      every sub-statement therein. Commands that alter the catalog will likely not
+      work as expected.
+     </para>
+ 
+     <para>  
+      For example: Issuing "CREATE TEMP TABLE" within an SQL function will add
+      the table to the catalog but subsequent statements in the same function will
+      not see those additions and thus the temporary table will be invisible to them.
+     </para>
+ 
+     <para>  
+      Thus it is generally advised that <application>PL/pgSQL</> be used, instead of
+      <acronym>SQL</acronym>, when any catalog visibilities are required in the same function.
+     </para>
+    </sect2>
+    
     <sect2 id="xfunc-sql-function-arguments">
      <title>Arguments for <acronym>SQL</acronym> Functions</title>