In databases, how do you determine whether making an index on one particular column is good, useless, or bad?

Question

In databases, how do you determine whether making an index on one particular column is good, useless, or bad?

In: Technology

Answer 1

Are you sorting or looking up data by said column very often? If so it may be a good candidate for an index.

Indexes help the database search for values in the specified column. If the column needs to be searched often it makes sense to index it to speed that search up. If you only use it every once in a while or if the values don’t help with lookup that much (for instance columns that only have a few distinct values) then it may not be worth the time spent keeping the index correct.