PG_SHDEPEND

PG_SHDEPEND records the dependency between database objects and shared objects, such as roles. Based on this information, GaussDB can ensure that those objects are unreferenced before attempting to delete them.

See also PG_DEPEND, which provides a similar function for dependencies involving objects within a single database.

PG_SHDEPEND is shared among all databases of cluster. That is, there is only one PG_SHDEPEND for each cluster, not for each database.

**Table 1** PG_SHDEPEND columns
Name	Type	Reference	Description
dbid	oid	OID in PG_DATABASE	OID of the database the dependent object is in, or zero for a shared object.
classid	oid	OID in PG_CLASS	OID of the system catalog where a dependent object resides.
objid	oid	Any OID column	OID of the dependent object.
objsubid	integer	-	Column number of a table column (the table to which the column points can be determined based on objid and classid). The value is 0 for all other object types.
refclassid	oid	OID in PG_CLASS	OID of the system catalog the referenced object is in (must be a shared catalog).
refobjid	oid	Any OID column	OID of the referenced object.
deptype	"char"	-	Code segment defining the specific semantics of this dependency relationship. The value can be o, a, p, d, or l. For details, see the following text.
objfile	text	-	Path of the user-defined C function library file.

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

SHARED_DEPENDENCY_OWNER (o)
The referenced object (which must be a role) is the owner of the dependent object.
SHARED_DEPENDENCY_ACL (a)
The referenced object (which must be a role) is mentioned in the access control list (ACL) of the dependent object. SHARED_DEPENDENCY_ACL is not added to the owner of the object because the owner will have a SHARED_DEPENDENCY_OWNER record.
SHARED_DEPENDENCY_PIN (p)
This type of record indicates that the system itself depends on the depended object. Therefore, such an object cannot be deleted. Entries of this type are created only by initdb. The columns for the dependent object contain zeroes.
SHARED_DEPENDENCY_ DBPRIV(d)
The referenced object (must be a role) has the ANY permission on the dependent object (the specified OID of the dependent object corresponds to a row in the GS_DB_PRIVILEGE system catalog).
SHARED_DEPENDENCY_ SECLABEL(l)
The referenced object (must be a security label) is applied to the dependent object.