<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >Event Trigger Functions</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK REV="MADE" HREF="mailto:pgsql-docs@postgresql.org"><LINK REL="HOME" TITLE="PostgreSQL 9.4.24 Documentation" HREF="index.html"><LINK REL="UP" TITLE="Functions and Operators" HREF="functions.html"><LINK REL="PREVIOUS" TITLE="Trigger Functions" HREF="functions-trigger.html"><LINK REL="NEXT" TITLE="Type Conversion" HREF="typeconv.html"><LINK REL="STYLESHEET" TYPE="text/css" HREF="stylesheet.css"><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"><META NAME="creation" CONTENT="2019-08-11T16:12:25"></HEAD ><BODY CLASS="SECT1" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="4" ALIGN="center" VALIGN="bottom" ><A HREF="index.html" >PostgreSQL 9.4.24 Documentation</A ></TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A TITLE="Trigger Functions" HREF="functions-trigger.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A HREF="functions.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="60%" ALIGN="center" VALIGN="bottom" >Chapter 9. Functions and Operators</TD ><TD WIDTH="20%" ALIGN="right" VALIGN="top" ><A TITLE="Type Conversion" HREF="typeconv.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="FUNCTIONS-EVENT-TRIGGERS" >9.28. Event Trigger Functions</A ></H1 ><P > Currently <SPAN CLASS="PRODUCTNAME" >PostgreSQL</SPAN > provides one built-in event trigger helper function, <CODE CLASS="FUNCTION" >pg_event_trigger_dropped_objects</CODE >. </P ><P > <CODE CLASS="FUNCTION" >pg_event_trigger_dropped_objects</CODE > returns a list of all objects dropped by the command in whose <TT CLASS="LITERAL" >sql_drop</TT > event it is called. If called in any other context, <CODE CLASS="FUNCTION" >pg_event_trigger_dropped_objects</CODE > raises an error. <CODE CLASS="FUNCTION" >pg_event_trigger_dropped_objects</CODE > returns the following columns: <DIV CLASS="INFORMALTABLE" ><P ></P ><A NAME="AEN22928" ></A ><TABLE BORDER="1" CLASS="CALSTABLE" ><COL><COL><COL><THEAD ><TR ><TH >Name</TH ><TH >Type</TH ><TH >Description</TH ></TR ></THEAD ><TBODY ><TR ><TD ><TT CLASS="LITERAL" >classid</TT ></TD ><TD ><TT CLASS="TYPE" >Oid</TT ></TD ><TD >OID of catalog the object belonged in</TD ></TR ><TR ><TD ><TT CLASS="LITERAL" >objid</TT ></TD ><TD ><TT CLASS="TYPE" >Oid</TT ></TD ><TD >OID the object had within the catalog</TD ></TR ><TR ><TD ><TT CLASS="LITERAL" >objsubid</TT ></TD ><TD ><TT CLASS="TYPE" >int32</TT ></TD ><TD >Object sub-id (e.g. attribute number for columns)</TD ></TR ><TR ><TD ><TT CLASS="LITERAL" >object_type</TT ></TD ><TD ><TT CLASS="TYPE" >text</TT ></TD ><TD >Type of the object</TD ></TR ><TR ><TD ><TT CLASS="LITERAL" >schema_name</TT ></TD ><TD ><TT CLASS="TYPE" >text</TT ></TD ><TD > Name of the schema the object belonged in, if any; otherwise <TT CLASS="LITERAL" >NULL</TT >. No quoting is applied. </TD ></TR ><TR ><TD ><TT CLASS="LITERAL" >object_name</TT ></TD ><TD ><TT CLASS="TYPE" >text</TT ></TD ><TD > Name of the object, if the combination of schema and name can be used as a unique identifier for the object; otherwise <TT CLASS="LITERAL" >NULL</TT >. No quoting is applied, and name is never schema-qualified. </TD ></TR ><TR ><TD ><TT CLASS="LITERAL" >object_identity</TT ></TD ><TD ><TT CLASS="TYPE" >text</TT ></TD ><TD > Text rendering of the object identity, schema-qualified. Each and every identifier present in the identity is quoted if necessary. </TD ></TR ></TBODY ></TABLE ><P ></P ></DIV > </P ><P > The <CODE CLASS="FUNCTION" >pg_event_trigger_dropped_objects</CODE > function can be used in an event trigger like this: </P><PRE CLASS="PROGRAMLISTING" >CREATE FUNCTION test_event_trigger_for_drops() RETURNS event_trigger LANGUAGE plpgsql AS $$ DECLARE obj record; BEGIN FOR obj IN SELECT * FROM pg_event_trigger_dropped_objects() LOOP RAISE NOTICE '% dropped object: % %.% %', tg_tag, obj.object_type, obj.schema_name, obj.object_name, obj.object_identity; END LOOP; END $$; CREATE EVENT TRIGGER test_event_trigger_for_drops ON sql_drop EXECUTE PROCEDURE test_event_trigger_for_drops();</PRE ><P> </P ><P > For more information about event triggers, see <A HREF="event-triggers.html" >Chapter 37</A >. </P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="functions-trigger.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="typeconv.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >Trigger Functions</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="functions.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >Type Conversion</TD ></TR ></TABLE ></DIV ></BODY ></HTML >