pg_depend

The pg_depend system catalog table records the dependency relationships between database objects. This information allows DROP commands to find which other objects must be dropped by DROP CASCADE or prevent dropping in the DROP RESTRICT case. See also pg_shdepend, which performs a similar function for dependencies involving objects that are shared across a Greengage DB system.

In all cases, a pg_depend entry indicates that the referenced object may not be dropped without also dropping the dependent object. However, there are several subflavors identified by deptype:

DEPENDENCY_NORMAL (n) — a normal relationship between separately created objects. The dependent object may be dropped without affecting the referenced object. The referenced object may only be dropped by specifying CASCADE, in which case the dependent object is dropped, too. Example: a table column has a normal dependency on its data type.
DEPENDENCY_AUTO (a) — the dependent object can be dropped separately from the referenced object, and should be automatically dropped (regardless of RESTRICT or CASCADE mode) if the referenced object is dropped. Example: a named constraint on a table is made auto-dependent on the table, so that it will go away if the table is dropped.
DEPENDENCY_INTERNAL (i) — the dependent object was created as part of creation of the referenced object, and is really just a part of its internal implementation. A DROP of the dependent object will be disallowed outright (we’ll tell the user to issue a DROP against the referenced object, instead). A DROP of the referenced object will be propagated through to drop the dependent object whether CASCADE is specified or not.
DEPENDENCY_PIN (p) — there is no dependent object; this type of entry is a signal that the system itself depends on the referenced object, and so that object must never be deleted. Entries of this type are created only by system initialization. The columns for the dependent object contain zeroes.

Column Type References Description

Column	Type	References	Description
classid	oid	pg_class.oid	The OID of the system catalog the dependent object is in
objid	oid	any OID column	The OID of the specific dependent object
objsubid	integer	—	For a table column, this is the column number. For all other object types, this column is `0`
refclassid	oid	pg_class.oid	The OID of the system catalog the referenced object is in
refobjid	oid	any OID column	The OID of the specific referenced object
refobjsubid	integer	—	For a table column, this is the referenced column number. For all other object types, this column is `0`
deptype	char	—	A code defining the specific semantics of this dependency relationship

classid

oid

pg_class.oid

The OID of the system catalog the dependent object is in

objid

oid

any OID column

The OID of the specific dependent object

objsubid

integer

—

For a table column, this is the column number. For all other object types, this column is 0

refclassid

oid

pg_class.oid

The OID of the system catalog the referenced object is in

refobjid

oid

any OID column

The OID of the specific referenced object

refobjsubid

integer

—

For a table column, this is the referenced column number. For all other object types, this column is 0

deptype

char

—

A code defining the specific semantics of this dependency relationship

pg_db_role_setting

pg_description