How important is the order of indexes?
When you create composite indexes the order of columns in composite index is also of prime importance. For instance for the below customer table we have created an index with ‘customercode’ as the first column and ‘customerid’ as the second column. If most of the SQL statements in your project are as shown below, i.e. with ‘customerid’ as the first column in the where clause then ‘customerid’ should be the first column in the composite index.
