Presents your 
SQL SERVER E-NEWSLETTER for February 6, 2003

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OPTIMIZE QUERIES WITH SEARCH ARGUMENTS

The optimizer in SQL Server uses search arguments (SARGs) to filter
queries. When you use the Display Estimated Execution Plan icon in Query
Analyzer, it will produce a graphical display of the execution plan. 
When you place the mouse over the lower rightmost graphical element, a pop-up
window will display statistics regarding the table. At the bottom of the
window is listed information regarding arguments.

The arguments are the potential SARGs. They would be identified at the
bottom of the window with an indication that the optimizer could be 
used to filter the data.

There are guidelines to help a query qualify for a SARG that the
optimizer can use:

* The filtering formula is present in the WHERE clause.

* A column of the table is in its raw format of the WHERE clause.

* A constant or variable containing a constant value is in the WHERE clause.

* An operator comparing the column and the constant or variable is involved.

The filtering formula consists of the column, constant or variable, and
operator. All three mechanisms must be present in the filtering formula.

The operator for a SARG may be one of the following:

* =
* <
* >
* >=
* <=
* BETWEEN
* LIKE

When the wildcard is being used with the LIKE operator, and the position
of the wildcard is at the beginning of the constant or variable, it will
not be used by the optimizer.

These operators most likely preclude the query from being used by the optimizer:

* NOT
* !=
* <>
* !>
* !<
* NOT EXISTS
* NOT IN
* NOT LIKE

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