53.5. pg_amproc

53.5. 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 53.5. pg_amproc Columns

Column Type Description
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.

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原文：PostgreSQL 15.19 Documentation（英文原文，待翻譯）