Improve documentation of pg_typeof, per gripe from David Wheeler.

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 61460f3c0fccd56993ed39cb558f4e7392f294a0..1e329904512b826d1c69742d80e5ff6dde8ad875 100644 (file)
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -1,4 +1,4 @@
-
+
 
  
   Functions and Operators
@@ -11871,7 +11871,24 @@ SELECT pg_type_is_visible('myschema.widget'::regtype);
   
    pg_typeof returns the OID of the data type of the
    value that is passed to it.  This can be helpful for troubleshooting or
-   dynamically constructing SQL queries.
+   dynamically constructing SQL queries.  The function is declared as
+   returning regtype, which is an OID alias type (see
+   ); this means that it is the same as an
+   OID for comparison purposes but displays as a type name.  For example:
+
+SELECT pg_typeof(33);
+
+ pg_typeof 
+-----------
+ integer
+(1 row)
+
+SELECT typlen FROM pg_type WHERE oid = pg_typeof(33);
+ typlen 
+--------
+      4
+(1 row)
+