My database is for an HR application with performance reviews and I am interested in whether I should index my foreign key.
There are two tables involved. The first is a ratings table with 2 columns:
ID (Integer, Primary Key) and
Description (Varchar). It will only have 4 rows (poor, average, above average and excellent) and will "never" change.
The second table is a review table. There will be 1 row for each employee every six months. So we are looking at thousands of entries and not millions. Each row has approximately 25 evaluation fields, which are foreign keys into the rating table. Examples would be typical questions where employee is rated on Completing Work on Time, Works well with others etc...
From what I've researched, there doesn't appear to be any real reason to create an index on each of those keys since I will never be adding and/or deleting from the ratings table. Are there any other considerations that I should take into account? Or am I worrying about nothing since by db is so small?