</para>

<para>

For user-defined functions, <productname>PostgreSQL</productname> tracks

dependencies associated with a function's externally-visible properties,

For a user-defined function or procedure whose body is defined as a string

literal, <productname>PostgreSQL</productname> tracks

dependencies associated with the function's externally-visible properties,

such as its argument and result types, but <emphasis>not</emphasis> dependencies

that could only be known by examining the function body. As an example,

consider this situation:

table is missing, though executing it would cause an error; creating a new

table of the same name would allow the function to work again.

</para>

<para>

On the other hand, for a SQL-language function or procedure whose body

is written in SQL-standard style, the body is parsed at function

definition time and all dependencies recognized by the parser are

stored. Thus, if we write the function above as

<programlisting>

CREATE FUNCTION get_color_note (rainbow) RETURNS text

BEGIN ATOMIC

SELECT note FROM my_colors WHERE color = $1;

END;

</programlisting>

then the function's dependency on the <structname>my_colors</structname>

table will be known and enforced by <command>DROP</command>.

</para>

</sect1>

</chapter>