PG_RANGE

PG_RANGE records information about range types. Entries in PG_TYPE are excluded.

Table 1 PG_RANGE columns

Name	Type	Reference	Description
rngtypid	oid	PG_TYPE.oid	OID of the range type
rngsubtype	oid	PG_TYPE.oid	OID of the element type (subtype) of this range type
rngcollation	oid	PG_COLLATION.oid	OID of the collation used for range comparisons (0 if none)
rngsubopc	oid	PG_OPCLASS.oid	OID of the subtype's operator class used for range comparisons
rngcanonical	regproc	PG_PROC.proname	Name of the function to convert a range value into canonical form (0 if none)
rngsubdiff	regproc	PG_PROC.proname	Name of the function to return the difference between two element values as double precision (0 if none)

rngsubopc (together with rngcollation, if the element type is collatable) determines the sort ordering used by the range type. rngcanonical is used when the element type is discrete.