Fill in information schema column for trigger WHEN condition

doc/src/sgml/information_schema.sgml

-<!-- $PostgreSQL: pgsql/doc/src/sgml/information_schema.sgml,v 1.42 2009/12/05 21:31:05 petere Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/information_schema.sgml,v 1.43 2009/12/30 22:48:10 petere Exp $ -->
 
 <chapter id="information-schema">
  <title>The Information Schema</title>
@@ -4875,7 +4875,11 @@ ORDER BY c.ordinal_position;
      <row>
       <entry><literal>action_condition</literal></entry>
       <entry><type>character_data</type></entry>
-      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
+      <entry>
+       <literal>WHEN</literal> condition of the trigger, null if none
+       (also null if the table is not owned by a currently enabled
+       role)
+      </entry>
      </row>
 
      <row>

src/backend/catalog/information_schema.sql

@@ -4,7 +4,7 @@
  *
  * Copyright (c) 2003-2009, PostgreSQL Global Development Group
  *
- * $PostgreSQL: pgsql/src/backend/catalog/information_schema.sql,v 1.60 2009/12/07 05:22:21 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/catalog/information_schema.sql,v 1.61 2009/12/30 22:48:10 petere Exp $
  */
 
 /*
@@ -1909,7 +1909,12 @@ CREATE VIEW triggers AS
            CAST(n.nspname AS sql_identifier) AS event_object_schema,
            CAST(c.relname AS sql_identifier) AS event_object_table,
            CAST(null AS cardinal_number) AS action_order,
-           CAST(null AS character_data) AS action_condition,
+           -- XXX strange hacks follow
+           CAST(
+             CASE WHEN pg_has_role(c.relowner, 'USAGE')
+               THEN (SELECT m[1] FROM regexp_matches(pg_get_triggerdef(t.oid), E'.{35,} WHEN \\((.+)\\) EXECUTE PROCEDURE') AS rm(m) LIMIT 1)
+               ELSE null END
+             AS character_data) AS action_condition,
            CAST(
              substring(pg_get_triggerdef(t.oid) from
                        position('EXECUTE PROCEDURE' in substring(pg_get_triggerdef(t.oid) from 48)) + 47)