# 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

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.