53.33. pg_opclass

53.33. `pg_opclass`
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53.33. `pg_opclass` #

+ The catalog pg_opclass defines + index access method operator classes. Each operator class defines + semantics for index columns of a particular data type and a particular + index access method. An operator class essentially specifies that a + particular operator family is applicable to a particular indexable column + data type. The set of operators from the family that are actually usable + with the indexed column are whichever ones accept the column's data type + as their left-hand input. +

+ Operator classes are described at length in Section 38.16. +

Table 53.33. pg_opclass Columns

+ Column Type + + + Description +
+ `oid` `oid` + + + Row identifier +
+ `opcmethod` `oid` + (references `pg_am`.`oid`) + + + Index access method operator class is for +
+ `opcname` `name` + + + Name of this operator class +
+ `opcnamespace` `oid` + (references `pg_namespace`.`oid`) + + + Namespace of this operator class +
+ `opcowner` `oid` + (references `pg_authid`.`oid`) + + + Owner of the operator class +
+ `opcfamily` `oid` + (references `pg_opfamily`.`oid`) + + + Operator family containing the operator class +
+ `opcintype` `oid` + (references `pg_type`.`oid`) + + + Data type that the operator class indexes +
+ `opcdefault` `bool` + + + True if this operator class is the default for `opcintype` +
+ `opckeytype` `oid` + (references `pg_type`.`oid`) + + + Type of data stored in index, or zero if same as `opcintype` +

+ Column Type +

+ Description +

+ oid oid +

+ Row identifier +

+ opcmethod oid + (references pg_am.oid) +

+ Index access method operator class is for +

+ opcname name +

+ Name of this operator class +

+ opcnamespace oid + (references pg_namespace.oid) +

+ Namespace of this operator class +

+ opcowner oid + (references pg_authid.oid) +

+ Owner of the operator class +

+ opcfamily oid + (references pg_opfamily.oid) +

+ Operator family containing the operator class +

+ opcintype oid + (references pg_type.oid) +

+ Data type that the operator class indexes +

+ opcdefault bool +

+ True if this operator class is the default for opcintype +

+ opckeytype oid + (references pg_type.oid) +

+ Type of data stored in index, or zero if same as opcintype +

+ An operator class's opcmethod must match the + opfmethod of its containing operator family. + Also, there must be no more than one pg_opclass + row having opcdefault true for any given combination of + opcmethod and opcintype. +

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53.32. `pg_namespace`	Home	53.34. `pg_operator`

53.33. pg_opclass #

53.33. `pg_opclass` #