mirrors/postgres
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Add GUC for temporarily disabling event triggers

Browse Source 
In order to troubleshoot misbehaving or buggy event triggers, the
documented advice is to enter single-user mode.  In an attempt to
reduce the number of situations where single-user mode is required
(or even recommended) for non-extraordinary maintenance, this GUC
allows to temporarily suspend event triggers.

This was originally extracted from a larger patchset which aimed
at supporting event triggers on login events.

Reviewed-by: Ted Yu <yuzhihong@gmail.com>
Reviewed-by: Mikhail Gribkov <youzhick@gmail.com>
Reviewed-by: Justin Pryzby <pryzby@telsasoft.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz
Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Discussion: https://postgr.es/m/9140106E-F9BF-4D85-8FC8-F2D3C094A6D9@yesql.se
Discussion: https://postgr.es/m/0d46d29f-4558-3af9-9c85-7774e14a7709@postgrespro.ru
This commit is contained in:
Daniel Gustafsson 2023-09-25 12:41:49 +02:00
parent f19669fed3
commit 7750fefdb2
8 changed files with 98 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
doc/src/sgml/config.sgml
View File

@ -9425,6 +9425,25 @@ SET XML OPTION { DOCUMENT | CONTENT };
</listitem>
</varlistentry>
<varlistentry id="guc-event-triggers" xreflabel="event_triggers">
<term><varname>event_triggers</varname> (<type>boolean</type>)
<indexterm>
<primary><varname>event_triggers</varname></primary>
<secondary>configuration parameter</secondary>
</indexterm>
</term>
<listitem>
<para>
Allow temporarily disabling execution of event triggers in order to
troubleshoot and repair faulty event triggers. All event triggers will
be disabled by setting it to <literal>false</literal>. Setting the value
to <literal>true</literal> allows all event triggers to fire, this
is the default value. Only superusers and users with the appropriate
<literal>SET</literal> privilege can change this setting.
</para>
</listitem>
</varlistentry>
</variablelist>
</sect2>
<sect2 id="runtime-config-client-format">

9
doc/src/sgml/ref/create_event_trigger.sgml
View File

@ -121,9 +121,12 @@ CREATE EVENT TRIGGER <replaceable class="parameter">name</replaceable>
<para>
Event triggers are disabled in single-user mode (see <xref
linkend="app-postgres"/>). If an erroneous event trigger disables the
database so much that you can't even drop the trigger, restart in
single-user mode and you'll be able to do that.
linkend="app-postgres"/>) as well as when
<xref linkend="guc-event-triggers"/> is set to <literal>false</literal>.
If an erroneous event trigger disables the database so much that you can't
even drop the trigger, restart with <xref linkend="guc-event-triggers"/>
set to <literal>false</literal> to temporarily disable event triggers, or
in single-user mode, and you'll be able to do that.
</para>
</refsect1>

20
src/backend/commands/event_trigger.c
View File

@ -72,6 +72,9 @@ typedef struct EventTriggerQueryState
static EventTriggerQueryState *currentEventTriggerState = NULL;
/* GUC parameter */
bool event_triggers = true;
/* Support for dropped objects */
typedef struct SQLDropObject
{
@ -657,8 +660,11 @@ EventTriggerDDLCommandStart(Node *parsetree)
* wherein event triggers are disabled. (Or we could implement
* heapscan-and-sort logic for that case, but having disaster recovery
* scenarios depend on code that's otherwise untested isn't appetizing.)
*
* Additionally, event triggers can be disabled with a superuser-only GUC
* to make fixing database easier as per 1 above.
*/
if (!IsUnderPostmaster)
if (!IsUnderPostmaster || !event_triggers)
return;
runlist = EventTriggerCommonSetup(parsetree,
@ -692,9 +698,9 @@ EventTriggerDDLCommandEnd(Node *parsetree)
/*
* See EventTriggerDDLCommandStart for a discussion about why event
* triggers are disabled in single user mode.
* triggers are disabled in single user mode or via GUC.
*/
if (!IsUnderPostmaster)
if (!IsUnderPostmaster || !event_triggers)
return;
/*
@ -740,9 +746,9 @@ EventTriggerSQLDrop(Node *parsetree)
/*
* See EventTriggerDDLCommandStart for a discussion about why event
* triggers are disabled in single user mode.
* triggers are disabled in single user mode or via a GUC.
*/
if (!IsUnderPostmaster)
if (!IsUnderPostmaster || !event_triggers)
return;
/*
@ -811,9 +817,9 @@ EventTriggerTableRewrite(Node *parsetree, Oid tableOid, int reason)
/*
* See EventTriggerDDLCommandStart for a discussion about why event
* triggers are disabled in single user mode.
* triggers are disabled in single user mode or via a GUC.
*/
if (!IsUnderPostmaster)
if (!IsUnderPostmaster || !event_triggers)
return;
/*

11
src/backend/utils/misc/guc_tables.c
View File

@ -37,6 +37,7 @@
#include "catalog/namespace.h"
#include "catalog/storage.h"
#include "commands/async.h"
#include "commands/event_trigger.h"
#include "commands/tablespace.h"
#include "commands/trigger.h"
#include "commands/user.h"
@ -2000,6 +2001,16 @@ struct config_bool ConfigureNamesBool[] =
NULL, NULL, NULL
},
{
{"event_triggers", PGC_SUSET, CLIENT_CONN_STATEMENT,
gettext_noop("Enables event triggers."),
gettext_noop("When enabled, event triggers will fire for all applicable statements."),
},
&event_triggers,
true,
NULL, NULL, NULL
},
/* End-of-list marker */
{
{NULL, 0, 0, NULL, NULL}, NULL, false, NULL, NULL, NULL

1
src/backend/utils/misc/postgresql.conf.sample
View File

@ -706,6 +706,7 @@
#xmloption = 'content'
#gin_pending_list_limit = 4MB
#createrole_self_grant = '' # set and/or inherit
#event_triggers = on
# - Locale and Formatting -

2
src/include/commands/event_trigger.h
View File

@ -29,6 +29,8 @@ typedef struct EventTriggerData
CommandTag tag;
} EventTriggerData;
extern PGDLLIMPORT bool event_triggers;
#define AT_REWRITE_ALTER_PERSISTENCE 0x01
#define AT_REWRITE_DEFAULT_VAL 0x02
#define AT_REWRITE_COLUMN_REWRITE 0x04

22
src/test/regress/expected/event_trigger.out
View File

@ -616,3 +616,25 @@ SELECT
DROP EVENT TRIGGER start_rls_command;
DROP EVENT TRIGGER end_rls_command;
DROP EVENT TRIGGER sql_drop_command;
-- Check the GUC for disabling event triggers
CREATE FUNCTION test_event_trigger_guc() RETURNS event_trigger
LANGUAGE plpgsql AS $$
DECLARE
obj record;
BEGIN
FOR obj IN SELECT * FROM pg_event_trigger_dropped_objects()
LOOP
RAISE NOTICE '% dropped %', tg_tag, obj.object_type;
END LOOP;
END;
$$;
CREATE EVENT TRIGGER test_event_trigger_guc
ON sql_drop
WHEN TAG IN ('DROP POLICY') EXECUTE FUNCTION test_event_trigger_guc();
SET event_triggers = 'on';
CREATE POLICY pguc ON event_trigger_test USING (FALSE);
DROP POLICY pguc ON event_trigger_test;
NOTICE: DROP POLICY dropped policy
CREATE POLICY pguc ON event_trigger_test USING (FALSE);
SET event_triggers = 'off';
DROP POLICY pguc ON event_trigger_test;

24
src/test/regress/sql/event_trigger.sql
View File

@ -471,3 +471,27 @@ SELECT
DROP EVENT TRIGGER start_rls_command;
DROP EVENT TRIGGER end_rls_command;
DROP EVENT TRIGGER sql_drop_command;
-- Check the GUC for disabling event triggers
CREATE FUNCTION test_event_trigger_guc() RETURNS event_trigger
LANGUAGE plpgsql AS $$
DECLARE
obj record;
BEGIN
FOR obj IN SELECT * FROM pg_event_trigger_dropped_objects()
LOOP
RAISE NOTICE '% dropped %', tg_tag, obj.object_type;
END LOOP;
END;
$$;
CREATE EVENT TRIGGER test_event_trigger_guc
ON sql_drop
WHEN TAG IN ('DROP POLICY') EXECUTE FUNCTION test_event_trigger_guc();
SET event_triggers = 'on';
CREATE POLICY pguc ON event_trigger_test USING (FALSE);
DROP POLICY pguc ON event_trigger_test;
CREATE POLICY pguc ON event_trigger_test USING (FALSE);
SET event_triggers = 'off';
DROP POLICY pguc ON event_trigger_test;