Join Table

Hello,

I have created the following join table: the two FKs are the PK of the 
table. Typically, I will need to select rows for a given ITEM_FK.

Question: is it necessary/advisable to create an index for the ITEM_FK 
column? Or is this redundantbecause this column is already one of the PK 
columns?

CREATE TABLE SUPPLY
(
ITEM_FK integer NOT NULL,
CONTACT_FK integer NOT NULL,
COST numeric (7,2),
PRIMARY KEY (ITEM_FK,CONTACT_FK)
);


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Regards/Gruß,

Tarlika Elisabeth Schmitz