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Note: The following description applies both to Postgres-XC and PostgreSQL if not described explicitly. You can read PostgreSQL as Postgres-XC except for version number, which is specific to each product.
The catalog pg_amproc stores information about support procedures associated with access method operator families. There is one row for each support procedure belonging to an operator family.
Table 47-5. pg_amproc Columns
| Name | Type | References | Description |
|---|---|---|---|
| oid | oid | Row identifier (hidden attribute; must be explicitly selected) | |
| amprocfamily | oid | pg_opfamily.oid | The operator family this entry is for |
| amproclefttype | oid | pg_type.oid | Left-hand input data type of associated operator |
| amprocrighttype | oid | pg_type.oid | Right-hand input data type of associated operator |
| amprocnum | int2 | Support procedure number | |
| amproc | regproc | pg_proc.oid | OID of the procedure |
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 procedure supports. For some access methods these match the input data type(s) of the support procedure itself, for others not. There is a notion of "default" support procedures for an index, which are those with amproclefttype and amprocrighttype both equal to the index opclass's opcintype.