Performance Improvement Using Covering Index to Reduce Row Identifier Lookups

In the current era, data plays a vital role as data is everything nowadays. But availability of data in
very large quantity it has become tedious to retrieve the data in minimum time span. Various tools and
techniques are developed by various experts in this field. Query optimization is one of the important
features in the data retrieval. Very basic concepts in the DBMS are indexed key and non indexed
keys. The performance of the query is also depends on these keys. The greatest advantage of this
indexed coverage is that it will dramatically boost database efficiency because it includes all fields
needed by request and the best results are always obtained by filtering or joining parameters in the
index main fields and inserting the fields specified in the SELECT list into the INCLUDE portion of the
coverage table. The covering index helps one to handle non-key columns at a non-clustered index
leaf node so that, without looking through the basis list, the optimizer deletes the columns from the
index itself. Including for non-key tables provides SQL Server with the non-clustered index.