Mastering PostgreSQL 12 - Third Edition

Creating operator classes

Finally, all the components are in place, and it is possible to create the operator class that's needed by the index:

CREATE OPERATOR CLASS sva_special_ops FOR TYPE text USING btree AS    OPERATOR 1 <# ,    OPERATOR 2 <=# ,    OPERATOR 3 = ,    OPERATOR 4 >=# ,    OPERATOR 5 ># ,    FUNCTION 1 si_same(text, text);

The CREATE OPERATOR CLASS command connects strategies and operators to OPERATOR 1. <# means that strategy 1 will use the <# operator. Finally, the the _same function is connected with the operator class.

Note that the operator class has a name, and that it has been explicitly defined to work with B-trees. The operator class can already be used during index creation:

CREATE INDEX idx_special ON t_sva (sva sva_special_ops); ...