---
title: "pg_amproc"
id: catalog-pg-amproc
pg_version: "20devel"
---

<a id="catalog-pg-amproc"></a>

## 52.5. pg_amproc

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. 

**pg_amproc Columns**

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