PostgreSQLprovides these helper functions to retrieve information from event triggers.
For more information about event triggers, seeChapter 39.
pg_event_trigger_ddl_commands
returns a list ofDDLcommands executed by each user action, when invoked in a function attached to addl_command_end
event trigger. If called in any other context, an error is raised.pg_event_trigger_ddl_commands
returns one row for each base command executed; some commands that are a single SQL sentence may return more than one row. This function returns the following columns:
pg_event_trigger_dropped_objects
returns a list of all objects dropped by the command in whosesql_drop
event it is called. If called in any other context,pg_event_trigger_dropped_objects
raises an error.pg_event_trigger_dropped_objects
returns the following columns:
Thepg_event_trigger_dropped_objects
function can be used in an event trigger like this:
The functions shown inTable 9.90provide information about a table for which atable_rewrite
event has just been called. If called in any other context, an error is raised.
Table 9.90. Table Rewrite information
Thepg_event_trigger_table_rewrite_oid
function can be used in an event trigger like this:
Name
Type
Description
classid
Oid
OID of catalog the object belongs in
objid
Oid
OID of the object in the catalog
objsubid
integer
Object sub-id (e.g. attribute number for columns)
command_tag
text
command tag
object_type
text
Type of the object
schema_name
text
Name of the schema the object belongs in, if any; otherwiseNULL
. No quoting is applied.
object_identity
text
Text rendering of the object identity, schema-qualified. Each and every identifier present in the identity is quoted if necessary.
in_extension
bool
whether the command is part of an extension script
command
pg_ddl_command
A complete representation of the command, in internal format. This cannot be output directly, but it can be passed to other functions to obtain different pieces of information about the command.
Name
Type
Description
classid
Oid
OID of catalog the object belonged in
objid
Oid
OID the object had within the catalog
objsubid
int32
Object sub-id (e.g. attribute number for columns)
original
bool
Flag used to identify the root object(s) of the deletion
normal
bool
Flag indicating that there's a normal dependency relationship in the dependency graph leading to this object
is_temporary
bool
Flag indicating that the object was a temporary object.
object_type
text
Type of the object
schema_name
text
Name of the schema the object belonged in, if any; otherwiseNULL
. No quoting is applied.
object_name
text
Name of the object, if the combination of schema and name can be used as a unique identifier for the object; otherwiseNULL
. No quoting is applied, and name is never schema-qualified.
object_identity
text
Text rendering of the object identity, schema-qualified. Each and every identifier present in the identity is quoted if necessary.
address_names
text[]
An array that, together withobject_type
andaddress_args
, can be used by thepg_get_object_address()
to recreate the object address in a remote server containing an identically named object of the same kind.
address_args
text[]
Complement foraddress_names
above.
Name
Return Type
Description
pg_event_trigger_table_rewrite_oid()
Oid
The OID of the table about to be rewritten.
pg_event_trigger_table_rewrite_reason()
int
The reason code(s) explaining the reason for rewriting. The exact meaning of the codes is release dependent.