> For the complete documentation index, see [llms.txt](https://docs.postgresql.tw/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.postgresql.tw/15/internals/system-catalogs/pg_amproc.md).

# 53.5. pg\_amproc

## 53.5. 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.

**Table 53.5. `pg_amproc` Columns**

| <p>Column Type</p><p>Description</p>                                                                                                                                                                                    |
| ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| <p><code>oid</code> <code>oid</code></p><p>Row identifier</p>                                                                                                                                                           |
| <p><code>amprocfamily</code> <code>oid</code> (references <a href="/15/internals/system-catalogs/pg_opfamily.md"><code>pg\_opfamily</code></a>.<code>oid</code>)</p><p>The operator family this entry is for</p>        |
| <p><code>amproclefttype</code> <code>oid</code> (references <a href="/15/internals/system-catalogs/pg_type.md"><code>pg\_type</code></a>.<code>oid</code>)</p><p>Left-hand input data type of associated operator</p>   |
| <p><code>amprocrighttype</code> <code>oid</code> (references <a href="/15/internals/system-catalogs/pg_type.md"><code>pg\_type</code></a>.<code>oid</code>)</p><p>Right-hand input data type of associated operator</p> |
| <p><code>amprocnum</code> <code>int2</code></p><p>Support function number</p>                                                                                                                                           |
| <p><code>amproc</code> <code>regproc</code> (references <a href="/15/internals/system-catalogs/pg_proc.md"><code>pg\_proc</code></a>.<code>oid</code>)</p><p>OID of the function</p>                                    |

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`.

***

原文：[PostgreSQL 15.19 Documentation](/15/internals/system-catalogs/pg_amproc.md)（英文原文，待翻譯）


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