Understanding of Execution Plan????? Pls help me out!!

[papilon]

Hello friends!!


In Execution plan please somebody help me to understand I am new to it.

If I run one select statement having Execution plan...

1.first of all what we will watch closely so that it will understand easily i.e related to costing....

2.Here I am seeing factors like 'SELECT' ,' TOP' , Hash Match/Left Anti Semi Join.

3.Index Scan : Physical Operation and Logical Operation
Here only I can see some factores like

Physical Operation And Logical Operation

a)Row Count ===========26,795,748
b)Estimated Row Size ====132 (What this exactly means??)
c)I/O Cost ============ 209
d)CPU Cost ============29.5
e)Number Of Executes ====1
f)Cost ================238.884090(57%)
h)Subtree Cost ==========417
i)Estimated Row Count====26,795,748

4.Computer Scalar:
5.Stram Aggregate/Aggregate
6.Table Scan

Like That........

Please somebody guide me in that I will be thankful..

T.I.A

Shashank

[erickwidya]

The physical operator (Physical Operation) used, such as Hash Join or Nested Loops. Physical operators displayed in red indicate that the query optimizer has issued a warning, such as missing column statistics or missing join predicates. This can cause the query optimizer to choose a less-efficient query plan than otherwise expected. For more information about column statistics, see Statistical Information. The graphical execution plan suggests remedial action, such as creating or updating statistics, or creating an index. The missing column statistics and indexes can be immediately created or updated using the context menus of SQL Query Analyzer.

The logical operator (Logical Operation) that matches the physical operator, such as the Join operator. The logical operator, if different from the physical operator, is listed after the physical operator at the top of the ToolTip and separated by a forward slash ( / ).
The number of rows (Row Count) output by the operator.

The estimated size of the row (Estimated Row Size) output by the operator.

The estimated cost (I/O Cost) of all I/O activity for the operation. This value should be as low as possible.

The estimated cost for all CPU activity (CPU Cost) for the operation.

The number of times the operation was executed (Number of executes) during the query.

The cost to the query optimizer (Cost) in executing this operation, including cost of this operation as a percentage of the total cost of the query. Because the query engine selects the most efficient operation to perform the query or execute the statement, this value should be as low as possible.

The total cost to the query optimizer (Subtree cost) in executing this operation and all operations preceding it in the same subtree.

The predicates and parameters (Argument) used by the query.

see "Execution Plan options" in BOL for better reading

[papilon]

Hey guys!!!!!

Thanks That really helped me!!!!!!!!!!!


Shashank

[erickwidya]

anytime Shasank