Databases Reference
In-Depth Information
SELECT
in_row_data_page_count
,
row_count
FROM
sys
.
dm_db_partition_stats
WHERE
object_id
=
object_id
(
'Sales.SalesOrderDetail'
)
AND
index_id
=
1
Listing 3-59.
In this case I have 0.003125 + 0.00074074 * (1234 - 1), which comes to 0.916458, which is
the value shown as
Estimated
I/O
Cost
.
Finally, we add both costs, 0.133606 + 0.916458, to get 1.05006, which is the total
estimated cost of the operator. In the same way, adding the cost of all the operators
will give the total cost of the plan. In this case, the cost of the Clustered Index Scan
(1.05006) plus the cost of the first Compute Scalar operator (0.01214), the second
Compute Scalar operator (0.01213), and the cost of the Filter operator (0.0582322), will
give the total cost of the plan: 1.13256, as shown on Figure 3-16.
Figure 3-16:
Execution plan displaying total cost.
