Creating operator classes

Finally, all components are in place and it is finally possible to create the operator class 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. OPERATOR 1 <# means that strategy 1 will use the <# operator. Finally 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);

Creating the index works in a slightly different way than previously: sva sva_special_ops means that the sva column is indexed using the sva_special_ops operator class. If sva_special_ops is not explicitly used, then PostgreSQL will not go for our special sort order but decide on the default operator class.