SQL Server Execution Plans - Red Gate Software

Chapter 2: Graphical Execution Plans for Basic Queries
Associated with each operator icon, and displayed below it, is an estimated cost, assigned
by the optimizer. From the relative estimated cost displayed, we can identify the three
most costly operations in the plan, in descending order.
1. The Index Scan against the Person.Address table (31%).
2. The Hash Match join operation between the Person.Person table and the output
from the first Hash Match (21%).
3. The other Hash Match join operator between the Person.Address table and the
output from the Nested Loop operator (20%).
There are multiple problematic operators in this query since, in general, we're better off
with Seek operations instead of Scan operations. Figure 2-16 shows the properties of the
most expensive operator, as defined by the estimated costs.
Figure 2.16
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