PG_RANGE

PG_RANGE records information about range types, except for records of types in PG_TYPE.

**Table 1** PG_RANGE columns
Name	Type	Reference	Description
rngtypid	oid	oid in PG_TYPE	OID of the range type.
rngsubtype	oid	oid in PG_TYPE	OID of the element type (subtype) of this range type.
rngcollation	oid	oid in PG_COLLATION	OID of the collation used for range comparisons (0 if none).
rngsubopc	oid	oid in PG_OPCLASS	OID of the subtype's operator class used for range comparisons.
rngcanonical	regproc	proname in PG_PROC	Name of the function to convert a range value into canonical form (0 if none).
rngsubdiff	regproc	proname in PG_PROC	Name of the function used to calculate the difference between two elements in a range. The return value of the function is of the double-precision type. If the function does not exist, the value of rngsubdiff is 0.

If the element type is discrete, rngcanonical determines the collation used for the range type. If the element type is not collatable, rngsubopc determines the collation used for the range type. If the element type is collatable, rngsubopc and rngcollation determine the collation used for the range type.

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