From f28d9b10f73440adcb2e094440b4b213673e491b Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 19 Jun 2014 12:33:56 -0400
Subject: [PATCH] Document SQL functions' behavior of parsing the whole
function at once.
Haribabu Kommi, somewhat rewritten by me
---
doc/src/sgml/xfunc.sgml | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/doc/src/sgml/xfunc.sgml b/doc/src/sgml/xfunc.sgml
index 941b101f393..d759f3746b2 100644
--- a/doc/src/sgml/xfunc.sgml
+++ b/doc/src/sgml/xfunc.sgml
@@ -143,6 +143,21 @@ SELECT clean_emp();
</screen>
</para>
+ <note>
+ <para>
+ The entire body of a SQL function is parsed before any of it is
+ executed. While a SQL function can contain commands that alter
+ the system catalogs (e.g., <command>CREATE TABLE</>), the effects
+ of such commands will not be visible during parse analysis of
+ later commands in the function. Thus, for example,
+ <literal>CREATE TABLE foo (...); INSERT INTO foo VALUES(...);</literal>
+ will not work as desired if packaged up into a single SQL function,
+ since <structname>foo</> won't exist yet when the <command>INSERT</>
+ command is parsed. It's recommended to use <application>PL/PgSQL</>
+ instead of a SQL function in this type of situation.
+ </para>
+ </note>
+
<para>
The syntax of the <command>CREATE FUNCTION</command> command requires
the function body to be written as a string constant. It is usually
--
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