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 51.5. pg_amproc Columns
Name | Type | References | Description |
---|---|---|---|
oid | oid | Row identifier | |
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 function number | |
amproc | regproc | 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
.