<para>

The <literal>ddl_command_start</> event occurs just before the

execution of a <literal>CREATE</>, <literal>ALTER</>, or <literal>DROP</>

commmand. As an exception, however, this event does not occur for

command. As an exception, however, this event does not occur for

DDL commands targeting shared objects - databases, roles, and tablespaces

- or for command targeting event triggers themselves. The event trigger

mechanism does not support these object types.

<para>

The <literal>ddl_command_end</> event occurs just before returning

control from the execution of a <literal>CREATE</>, <literal>ALTER</>,

or <literal>DROP</>commmand. It shares the same exceptions as

or <literal>DROP</>command. It shares the same exceptions as

the <literal>ddl_command_start</> event.

</para>