52.5. pg_amproc
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## 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.

Table 52.5. pg_amproc Columns

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

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