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Document SQL functions' behavior of parsing the whole function at once.

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Haribabu Kommi, somewhat rewritten by me
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Tom Lane 2014-06-19 12:33:56 -04:00
parent 909cab8305
commit b488daf0d5
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15
doc/src/sgml/xfunc.sgml
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@ -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