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