## 52.5. `pg_amproc`

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 The catalog `pg_amproc` stores information about support functions associated with access method operator families. There is one row for each support function belonging to an operator family.

**Table 52.5. `pg_amproc` Columns**

|                                                    Column Type<br/><br/> Description                                                   |
|----------------------------------------------------------------------------------------------------------------------------------------|
|                                                  `oid` `oid`<br/><br/> Row identifier                                                  |
|   `amprocfamily` `oid` (references [`pg_opfamily`](catalog-pg-opfamily.html).`oid`)<br/><br/> The operator family this entry is for    |
| `amproclefttype` `oid` (references [`pg_type`](catalog-pg-type.html).`oid`)<br/><br/> Left-hand input data type of associated operator |
|`amprocrighttype` `oid` (references [`pg_type`](catalog-pg-type.html).`oid`)<br/><br/> Right-hand input data type of associated operator|
|                                          `amprocnum` `int2`<br/><br/> Support function number                                          |
|                 `amproc` `regproc` (references [`pg_proc`](catalog-pg-proc.html).`oid`)<br/><br/> OID of the function                  |

 The usual interpretation of the `amproclefttype` and `amprocrighttype` fields is that they identify the left and right input types of the operator(s) that a particular support function supports. For some access methods these match the input data type(s) of the support function itself, for others not. There is a notion of “default” support functions for an index, which are those with `amproclefttype` and `amprocrighttype` both equal to the index operator class's `opcintype`.

