MySQL: integer Index vs Varchar Index

Question

Is there any performance problem with index field data type?

Is integer index much faster than varchar index?

Answer 1

An integer index is faster than a varchar index because an integer occupies a less space within the database than a varchar. Therefore, it is much faster to find an integer than it is to find a varchar string - because less memory is required to cache the integer index. A smaller data type, means more records can fit into the index blocks. The more records that fit into each index block - the fewer reads are needed to find records.