I want to know the difference between ‘Using index condition’ and ‘Using where, Using index.’ I think both methods use an index to fetch the first result record set and filter the data using the WHERE condition.
Q1. What’s the difference?
Q2. Which one is better?
Using index condition : where condition contains indexed and non-indexed column and the optimizer will first resolve the indexed column and will look for the rows in the table for the other condition (index push down)
Using where; Using index : 'Using index' meaning not doing the scan of entire table. 'Using where' may still do the table scan on non-indexed column but it will use if there is any indexed column in the where condition first more like using index condition
Which is better? 'Using where; Using index' would be better then 'Using index condition' if query has index all covering.