EXPLAIN PLAN: what is the difference between “using where” and “using index” in MYSQL

Question

What is the major difference between 'uing where' and 'using index' in EXPLAIN plan of MYSQL.

I think this is just the searching for the records from disc vs searching from memory respectively.

Thanks, -UDAY

Answer 1

The documentation explains the difference:

• Using index means the requested column data can be fetched from the index only, without having to read the row data proper.

• Using where means the index is actually used for lookups, instead of only for fetching the requested column data.