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 | 
|---|
| 
        Row identifier | 
| 
        The operator family this entry is for | 
| 
        Left-hand input data type of associated operator | 
| 
        Right-hand input data type of associated operator | 
| 
        Support function number | 
| 
        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.