Using Clustered Index

This statement indicates that the query optimizer used the clustered index on a table to retrieve the rows. Unlike the table scan method, using an index to retrieve rows does not require the optimizer to examine every row in the table (unless the WHERE clause applies to all rows). For queries that return a small percentage of the rows from a large table, the savings in terms of I/Os of using an index versus doing a table scan can be very significant.

The following query shows the clustered index being used to retrieve the rows from the table:

Query:

SELECT title_id, title
FROM titles
WHERE title_id LIKE 'PS2%'

SHOWPLAN:

STEP 1
The type of query is SELECT
FROM TABLE
titles
Nested iteration
Using Clustered Index