To prevent servers from becoming inaccessible, such triggers must avoid

writing anything to the database when running on a standby.

Also, it's recommended to avoid long-running queries in

<literal>login</literal> event triggers.Notes that, for instance,

<literal>login</literal> event triggers.Note that, for instance,

canceling connection in <application>psql</application> wouldn't cancel

the in-progress <literal>login</literal> trigger.

</para>

<listitem>

<para>

Describes the event for which the function is called, one of

<literal>"ddl_command_start"</literal>, <literal>"ddl_command_end"</literal>,

<literal>"sql_drop"</literal>, <literal>"table_rewrite"</literal>.

<literal>"login"</literal>, <literal>"ddl_command_start"</literal>,

<literal>"ddl_command_end"</literal>, <literal>"sql_drop"</literal>,

<literal>"table_rewrite"</literal>.

See <xref linkend="event-trigger-definition"/> for the meaning of these

events.

</para>

This is the source code of the trigger function:

<programlisting><![CDATA[

#include "postgres.h"

#include "commands/event_trigger.h"

#include "commands/event_trigger.h"

#include "fmgr.h"

PG_MODULE_MAGIC;