From 399ad77c66a17ff354e5fbf01ca35c76e2ae88ed Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Fri, 7 Nov 2008 22:54:41 +0000
Subject: [PATCH] Improve documentation of pg_typeof, per gripe from David
Wheeler.
---
doc/src/sgml/func.sgml | 21 +++++++++++++++++++--
1 file changed, 19 insertions(+), 2 deletions(-)
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 61460f3c0fc..1e329904512 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.455 2008/11/04 14:49:11 petere Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.456 2008/11/07 22:54:41 tgl Exp $ -->
<chapter id="functions">
<title>Functions and Operators</title>
@@ -11871,7 +11871,24 @@ SELECT pg_type_is_visible('myschema.widget'::regtype);
<para>
<function>pg_typeof</function> 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 <type>regtype</>, which is an OID alias type (see
+ <xref linkend="datatype-oid">); this means that it is the same as an
+ OID for comparison purposes but displays as a type name. For example:
+<programlisting>
+SELECT pg_typeof(33);
+
+ pg_typeof
+-----------
+ integer
+(1 row)
+
+SELECT typlen FROM pg_type WHERE oid = pg_typeof(33);
+ typlen
+--------
+ 4
+(1 row)
+</programlisting>
</para>
<indexterm>
--
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