Category Archives: SQL Server 2008

SQL Server and Protocols

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TCP/IP and Named Pipes
By default, clients have TCP and Named Pipes as available protocols on most of client computer. You can manipulate the protocol ordering by using the SQL Server Client utility. The client application uses the protocols in the order specified on the client computer. If you are using SQL Server 2005, the protocol order is stored in the ProtocolOrder registry entry under the following registry subkey:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSSQLServer\Client\SNI9.0

IPX/SPX
SQL Server 2005 does not support IPX/SPX. The newer versions of NetWare, such as NetWare 6.5, support TCP/IP which makes it the common protocol for all clients.

VIA
The Virtual Interface Adapter (VIA) can be used only by VIA hardware.

Shared Memory
Shared Memory can only be used on the local computer and cannot be used as a network protocol.

Reference: Microsoft SQL Server 2005 Books Online (2006), Index: client connections [SQL Server], about client network connections, choosing a network protocol

Enabling Filestream to store compress documents

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Problem: If you are in the process of enabling FILESTREAM on volume and you also want to ensure that documents will be stored in the compressed form but during that time you notice that volume F:\ drive is not formatted. You need to make sure that the volume will be able to store documents in a compressed form.  You can fix the issue by using below command.

Command to format F:\
format F: /FS:NTFS /V:MYBLOBContainer/A:4096 /C

The above command will format the volume, convert it to NTFS and then label it as MYBLOBContainer. It will also set the NTFS cluster size to 4096. It is important to note that the cluster size must be 4096 or smaller for compression to be enabled for a volume. And at last, the /c parameter will compress the volume. When you are storing the FILESTREAM data, you can store it on a compressed or a non-compressed volume. The data in FILESTREAM is actually stored on the file system. There are a number of benefits to storing the data on the file system. For instance, you will be able to compress data with the NTFS compression capabilities. When the data is stored, it is in compressed form and when the data is retrieved, it is decompressed.

SQL Server 2008 Interview Q&A

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Which types of compression supported by SQL Server 2008?
SQL Server 2008 supports two types of compression namely as below

  • Database Backup Compression
  • Data Compression

Explain Database Backup Compression
SQL Server 2008 introduces a new feature called Database Backup Compression (DBC). This feature allows DBA’s to compress SQL Server 2008 database backups natively rather than taking uncompressed native SQL Server database backups or using a third-party tool. By default, database backup compression feature is turned off in the SQL Server 2008.
Using the Database Backup Compression feature, we can perform Full, Differential and Transactional log compressed backups.

Which SQL Server editions supports database backup compression feature?
Currently this feature is only available in the Enterprise Edition of SQL Server 2008. However, all editions of SQL Server 2008 allow the restoration of compressed database backup.

What are the pre-requisites for using database backup compression feature?

  1. SQL Server 2008 Enterprise edition
  2. Enable database compression at server level
  3. User WITH COMPRESSION clause while taking FULL, DIFFRENTIAL and LOG backup

How to enable database backup compression feature at server level?
You can use below TSQL code to enable the DBC at server level.
USE MASTER
GO
EXEC sp_configure ‘backup compression default’, ‘1’
GO
RECONFIGURE WITH OVERRIDE
GO

Table Locking enhancement – SQL Server 2008

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In SQL Server 2008 ALTER TABLE statement, you can find a new option called SET LOCK_ESCALATION. This is one of the enhancements in Locking in SQL Server 2008. This option can have three value, Auto, Table, Disable

FROM BOL
SET ( LOCK_ESCALATION = { AUTO | TABLE | DISABLE } )
Specifies the allowed methods of lock escalation for a table.

AUTO
This option allows SQL Server Database Engine to select the lock escalation granularity that is appropriate for the table schema.
• If the table is partitioned, lock escalation will be allowed to the heap or B-tree (HoBT) granularity. After the lock is escalated to the HoBT level, the lock will not be escalated later to TABLE granularity.
• If the table is not partitioned, the lock escalation will be done to the TABLE granularity.

TABLE
Lock escalation will be done at table-level granularity regardless whether the table is partitioned or not partitioned. This behavior is the same as in SQL Server 2005. TABLE is the default value.

DISABLE
Prevents lock escalation in most cases. Table-level locks are not completely disallowed. For example, when you are scanning a table that has no clustered index under the serializable isolation level, Database Engine must take a table lock to protect data integrity.

Note : If you use partitions then After you create a partitioned table, consider setting the LOCK_ESCALATION option for the table to AUTO. This can improve concurrency by enabling locks to escalate to partition (HoBT) level instead of the table.

Resource Governor in SQL Server 2008

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Resource Governor in SQL Server 2008

SQL Server 2008 Resource Governor allows you to control the resource according to the requirements. This was motive behind this feature is providing predictable response to the user in any situation. In earlier versions, we had a single pool of resources like Memory, CPU, threads etc. You can not priorities the workload versus Resource pool in 2005 and earlier version. Generally, who accesses the system first and starts a process, it can consume the resources without any restrictions. Consider, some kind of BI runaway query is first hit system where the OLTP and OLAP Databases are in the same server. Now the OLTP process has to wait till the OLAP process releases the resource. This was a major concern in earlier versions. So what were the solution then, go for multiple instances and configure the Resource per instance or go for different machine altogether. Both methods were having their own problem. By specifying the resource, if the system is not using that resource still will not released. If you go for another machine, you may have license issue and it’s not a cost effective method.

In SQL Server 2008, these problems are addressed by providing a tool called Resource Governor. You can differentiate the workload by Application Name, Login, Group, by database name etc. Once you have defined the workload, you can configure the resource which can consumed by workload. Probably, you want to give more resource for your OLTP application than the OLAP. You have that kind of flexibility and control here.
The following three concepts are fundamental to understanding and using Resource Governor:
• Resource pools: Two resource pools (internal and default) are created when SQL Server 2008 is installed. Resource Governor also supports user-defined resource pools.
• Workload groups: Two workload groups (internal and default) are created and mapped to their corresponding resource pools when SQL Server 2008 is installed. Resource Governor also supports user-defined workload groups.
• Classification: There are internal rules that classify incoming requests and route them to a workload group. Resource Governor also supports a classifier user-defined function for implementing classification rules.