pg_range

The catalog pg_range stores information about range types. This is in addition to the types' entries in pg_type .

Table 48-37. pg_range Columns

Name Type References 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, or 0 if none
rngsubopc oid pg_opclass .oid OID of the subtype's operator class used for range comparisons
rngcanonical regproc pg_proc .oid OID of the function to convert a range value into canonical form, or 0 if none
rngsubdiff regproc pg_proc .oid OID of the function to return the difference between two element values as double precision , or 0 if none

rngsubopc (plus 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. rngsubdiff is optional but should be supplied to improve performance of GiST indexes on the range type.