## 52.41. `pg_range`

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 The catalog `pg_range` stores information about range types. This is in addition to the types' entries in [`pg_type`](catalog-pg-type.html).

**Table 52.41. `pg_range` Columns**

|                                                                                  Column Type<br/><br/> Description                                                                                 |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|                                               `rngtypid` `oid` (references [`pg_type`](catalog-pg-type.html).`oid`)<br/><br/> OID of the range type                                                |
|                               `rngsubtype` `oid` (references [`pg_type`](catalog-pg-type.html).`oid`)<br/><br/> OID of the element type (subtype) of this range type                               |
|                                `rngmultitypid` `oid` (references [`pg_type`](catalog-pg-type.html).`oid`)<br/><br/> OID of the multirange type for this range type                                 |
|                   `rngcollation` `oid` (references [`pg_collation`](catalog-pg-collation.html).`oid`)<br/><br/> OID of the collation used for range comparisons, or zero if none                   |
|                       `rngsubopc` `oid` (references [`pg_opclass`](catalog-pg-opclass.html).`oid`)<br/><br/> OID of the subtype's operator class used for range comparisons                        |
|             `rngcanonical` `regproc` (references [`pg_proc`](catalog-pg-proc.html).`oid`)<br/><br/> OID of the function to convert a range value into canonical form, or zero if none              |
|`rngsubdiff` `regproc` (references [`pg_proc`](catalog-pg-proc.html).`oid`)<br/><br/> OID of the function to return the difference between two element values as `double precision`, or zero 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.

