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v1.1

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PG_AMOP

PG_AMOP records information about operators associated with access method operator families. There is one row for each operator that is a member of an operator family. A family member can be either a search operator or an ordering operator. An operator can appear in more than one family, but cannot appear in more than one search position nor more than one ordering position within a family.

Table 1 PG_AMOP columns

Name Type Reference Description
oid oid - Row identifier (hidden attribute, which must be specified)
amopfamily oid PG_OPFAMILY.oid Operator family of this entry
amoplefttype oid PG_TYPE.oid Left-hand input data type of the operator
amoprighttype oid PG_TYPE.oid Right-hand input data type of the operator
amopstrategy smallint - Number of operator strategies
amoppurpose "char" - Operator purpose, either s for search or o for ordering
amopopr oid PG_OPERATOR.oid OID of the operator
amopmethod oid PG_AM.oid Operator family of the index access method
amopsortfamily oid PG_OPFAMILY.oid The B-tree operator family according to which this entry sorts for an ordering operator (0 for a search operator)

A search operator entry indicates that an index of this operator family can be searched to find all rows satisfying WHERE indexed_column operator constant. Obviously, such an operator must return a Boolean value, and its left-hand input type must match the index's column data type.

An ordering operator entry indicates that an index of this operator family can be scanned to return rows in the order represented by ORDER BY indexed_column operator constant. Such an operator could return any sortable data type, though again its left-hand input type must match the index's column data type. The exact semantics of ORDER BY are specified by the amopsortfamily column, which must reference the B-tree operator family for the operator's result type.

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