Filtered index in Microsoft SQL Server 2008

Filtered index in SQL Server 2008 is an index WHERE clause. A filtered index is an optimized non-clustered index. It allows for defining the filter predicate with WHERE clause at the time of creating index. The rows from the filtered index are available in B-Tree will contain the rows which only satisfy the criteria of the filter while creating the index.

The advantages of Filtered indexes are :

1. Has only that row which satisfies the filter criteria defined. This results in reducing the storage space need for the index.
2. The filtered index statistics are accurate and more compact. The reason is they consider only the tuples / rows in the filtered index and it reduces the cost of overhead of updating the statistics.
3. The data modification impact is less by using filtered index. Because it is updated only at the time where the data of the index is impacted.
4. The cost of maintenance will be reduced, because only the subset of rows will be considered which rebuilding the index.

Row Level and Page Level Data Compression in Microsoft SQL Server 2008

Data compression is a feature which is used to reduce disk storage space and increase the performance of the query by reducing the I/O operations.

SQL Server 2008 supports two types of compression :

Row-level compression 

Page-level compression.

A row-level and page-level compression takes place on the metadata. Page level compression results in persisting certain common data that affects rows in a single location. 

The compression takes place into number of bits. For example, the length of ‘varchar’ will be stored in 3 bits.

Automatic Auditing in Microsoft SQL Server 2008

Automatic auditing is a true auditing solution for enterprise customers. STL Trace can be used for satisfying several auditing needs. SQL Server Auditing feature offers a number of advantages that attracts and help DBAs with much more easily achievable goals. These include meeting regulatory compliance requirements. These are :

1. Provision for centralized storage of audit logs and integration with system center.
2. Better performance that is noticeable.
3. Permits free-grained auditing in which an audit can be targeted for some specific actions by a principle against a particular object.
4. Allows the objects of audit to be treated as first class database objects, which mean Transact-SQL DDL statements can create these objects.
5. The database object is controlled by database engine’s permission model and enforcement control.
6. A new level permission is featured in SQL Audit – ALTER ANY SERVER AUDIT- which allows a principle to CREATE, ALTER and DROP an Audit Specification object.
7. A database level permission – ALTER ANY DATABASE AUDIT – is introduced to allow a principle to CREATE, ALTER and DROP a Database specification object.

Compound Operators in Microsoft Sql Server 2008

Compound operators feature is enhanced in SQL Server 2008. They are like compound operators in languages like C, C++.

Compound operators are a combination of operator with another operator.

The compound assignment operators are : 

arithmetic operators - +=,-=,*=, /=, %=, and
bitwise operators -&=, ^=,|=

For example

Declare @number int
Set @number = 10
--using Compound assignment operator
Set @number+=200
Select @number as MyResult
Go

Inline variable Assignment Process in Microsoft Sql Server 2008

Inline variable assignment in SQL Server 2008 enables to – declare, and assign the variables in a ‘single line’.

For example :

In Traditional Way :

DECLARE @myVar int
SET @myVar = 5

need to declare the variable and assigning it to the variable to split into 2 

lines and use 2 statements - DECLARE and SET.

In SQL Server 2008, as the name suggests ‘inline’, both declaration and assignment can be given in a single line:

DECLARE @myVar int = 5