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 47-5. pg_amproc Columns
|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 opclass's opcintype.