diff options
Diffstat (limited to 'doc/src/sgml/man7/CREATE_EVENT_TRIGGER.7')
| -rw-r--r-- | doc/src/sgml/man7/CREATE_EVENT_TRIGGER.7 | 129 |
1 files changed, 129 insertions, 0 deletions
diff --git a/doc/src/sgml/man7/CREATE_EVENT_TRIGGER.7 b/doc/src/sgml/man7/CREATE_EVENT_TRIGGER.7 new file mode 100644 index 0000000..e85d653 --- /dev/null +++ b/doc/src/sgml/man7/CREATE_EVENT_TRIGGER.7 @@ -0,0 +1,129 @@ +'\" t +.\" Title: CREATE EVENT TRIGGER +.\" Author: The PostgreSQL Global Development Group +.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/> +.\" Date: 2023 +.\" Manual: PostgreSQL 15.4 Documentation +.\" Source: PostgreSQL 15.4 +.\" Language: English +.\" +.TH "CREATE EVENT TRIGGER" "7" "2023" "PostgreSQL 15.4" "PostgreSQL 15.4 Documentation" +.\" ----------------------------------------------------------------- +.\" * Define some portability stuff +.\" ----------------------------------------------------------------- +.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +.\" http://bugs.debian.org/507673 +.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html +.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +.ie \n(.g .ds Aq \(aq +.el .ds Aq ' +.\" ----------------------------------------------------------------- +.\" * set default formatting +.\" ----------------------------------------------------------------- +.\" disable hyphenation +.nh +.\" disable justification (adjust text to left margin only) +.ad l +.\" ----------------------------------------------------------------- +.\" * MAIN CONTENT STARTS HERE * +.\" ----------------------------------------------------------------- +.SH "NAME" +CREATE_EVENT_TRIGGER \- define a new event trigger +.SH "SYNOPSIS" +.sp +.nf +CREATE EVENT TRIGGER \fIname\fR + ON \fIevent\fR + [ WHEN \fIfilter_variable\fR IN (\fIfilter_value\fR [, \&.\&.\&. ]) [ AND \&.\&.\&. ] ] + EXECUTE { FUNCTION | PROCEDURE } \fIfunction_name\fR() +.fi +.SH "DESCRIPTION" +.PP +\fBCREATE EVENT TRIGGER\fR +creates a new event trigger\&. Whenever the designated event occurs and the +WHEN +condition associated with the trigger, if any, is satisfied, the trigger function will be executed\&. For a general introduction to event triggers, see +Chapter\ \&40\&. The user who creates an event trigger becomes its owner\&. +.SH "PARAMETERS" +.PP +\fIname\fR +.RS 4 +The name to give the new trigger\&. This name must be unique within the database\&. +.RE +.PP +\fIevent\fR +.RS 4 +The name of the event that triggers a call to the given function\&. See +Section\ \&40.1 +for more information on event names\&. +.RE +.PP +\fIfilter_variable\fR +.RS 4 +The name of a variable used to filter events\&. This makes it possible to restrict the firing of the trigger to a subset of the cases in which it is supported\&. Currently the only supported +\fIfilter_variable\fR +is +TAG\&. +.RE +.PP +\fIfilter_value\fR +.RS 4 +A list of values for the associated +\fIfilter_variable\fR +for which the trigger should fire\&. For +TAG, this means a list of command tags (e\&.g\&., +\*(AqDROP FUNCTION\*(Aq)\&. +.RE +.PP +\fIfunction_name\fR +.RS 4 +A user\-supplied function that is declared as taking no argument and returning type +event_trigger\&. +.sp +In the syntax of +CREATE EVENT TRIGGER, the keywords +FUNCTION +and +PROCEDURE +are equivalent, but the referenced function must in any case be a function, not a procedure\&. The use of the keyword +PROCEDURE +here is historical and deprecated\&. +.RE +.SH "NOTES" +.PP +Only superusers can create event triggers\&. +.PP +Event triggers are disabled in single\-user mode (see +\fBpostgres\fR(1))\&. If an erroneous event trigger disables the database so much that you can\*(Aqt even drop the trigger, restart in single\-user mode and you\*(Aqll be able to do that\&. +.SH "EXAMPLES" +.PP +Forbid the execution of any +DDL +command: +.sp +.if n \{\ +.RS 4 +.\} +.nf +CREATE OR REPLACE FUNCTION abort_any_command() + RETURNS event_trigger + LANGUAGE plpgsql + AS $$ +BEGIN + RAISE EXCEPTION \*(Aqcommand % is disabled\*(Aq, tg_tag; +END; +$$; + +CREATE EVENT TRIGGER abort_ddl ON ddl_command_start + EXECUTE FUNCTION abort_any_command(); +.fi +.if n \{\ +.RE +.\} +.SH "COMPATIBILITY" +.PP +There is no +\fBCREATE EVENT TRIGGER\fR +statement in the SQL standard\&. +.SH "SEE ALSO" +ALTER EVENT TRIGGER (\fBALTER_EVENT_TRIGGER\fR(7)), DROP EVENT TRIGGER (\fBDROP_EVENT_TRIGGER\fR(7)), CREATE FUNCTION (\fBCREATE_FUNCTION\fR(7)) |