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 49-5. 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 operator class's opcintype .