Query with using single index

Question

I have what seems like a pretty straight forward problem. I have a table, say TAB_A that has a NAME, PHONE, SSN along with some other values (no primary key...I know, don't start with me. That's just the way it is.) I want to retrieve records where the NAME or the PHONE, or the SSN match a static value. I realize I could write this as:
WHERE name = 'Joe' OR phone = '5556667777' or ssn = '012345678'
However, when you do this (assuming there is a concatenated index on name, phone, ssn), you end up doing an index full scan. If you create three individual indexes on each column then you can write a union query that utilizes the index for each value...eg.
select...
where name = 'Joe'
union
select...
where phone = '555667777'
union
etc.
However, here you are writing three separate queries that each do an index range scan. I'm just wondering if there is some way to do this...say with some sort of function based index and a hashing algorithm applied to the data where I can do this in a single index range scan? Any ideas?

Answer 1

I don't see how a single index entry can point to a row that doesn't exist (in all likelihood).
Without testing it, I don't see how even a concatenated index could help.
The rows returned by your query are completely unrelated (unless you find the one person who has all three).
By the way, 7 posts in 10 years. Now that's what I call a lurker.