I know that indexes are automatically built when creating , say, a FK to PK relation. And it is clear that indexes allow for the enforcement of rules when incoming rows are getting updated or coming in. My question is if having a FK to PK relation will increase performance when querying versus having plain indexes in both tables without IC. If there is a performance increase that the table with the FK does not need to consult its index but uses the PK index? Is there any performance boost when having IC as opposed to simple indexes?
The main application for IC is updating tables, not querying.
I have seen no examples nor documentation that indicates that the SQL/WHERE-planner takes IC into account.
So my qualified guess is no, there is probably be no difference.