The data compression feature in SQL Server 2008 helps compress the data inside a database, and it can help reduce the size of the database. Apart from the space savings, data compression provides another benefit: Because compressed data is stored in fewer pages, queries need to read fewer pages from the disk, thereby improving the performance of I/O intensive workloads. However, extra CPU resources are required on the database server to compress and decompress the data, while data is exchanged with the application. Therefore, it is important to understand the workload characteristics when deciding which tables to compress.

This white paper provides guidance on the following:

• How to decide which tables and indexes to compress
• How to estimate the resources required to compress a table
• How to reclaim space released by data compression
• The performance impacts of data compression on typical workloads

Read Whitepaper: Data Compression Strategy Capacity Planning and Best Practices

Reference: Pinal Dave (http://blog.SQLAuthority.com)

Introduction

This article is based on a real life experience of the author while working with database backup and restore during his consultancy work for various organizations. We will go over the following important concepts of database backup and restore.

1. Conventional Backup and Restore
2. Spilt File Backup and Restore
3. Mirror File Backup
4. Understanding FORMAT Clause
5. Miscellaneous details about Backup and Restore

In our example, we will require the following folders:

• C:\Backup\SingleFile
• C:\Backup\MultiFile
• C:\Backup\MirrorFile

Conventional and Split File Backup and Restore

Just a day before working on one of the projects, I had to take a backup of one database of 14 GB. My hard drive lacked sufficient space at that moment. Fortunately, I had two 8 GB USB Drives with me. Now, the question was how to take a backup in two equal sizes, each of 7 GB, so I can fit them on each USB drive. Well, conventional backup takes one large backup in one file. However, SQL Server backup command can take backups in two or more split parts.

Let us see an example of a conventional one-file backup using the AdventureWorks database.

The result is displayed below. Here, the backup is taken in a single file.

Now, let us see how we can split one database into two different database files. This method is very similar to taking a single-file backup. By simply adding an additional DISK option we can split the files backup files.

In the previous example, we can clearly see that backup is split into three equal parts of the original backup file size.

Restoring a backup from a single-file backup is quite easy. Let us go over an example where we restore the AdventureWorks database from a single backup file.

Running the above script will give a successful message.

Now let us see an example where we restore a database from a split file. This method is very similar to restoring a database from a single file; just add an additional DISK option.

Running the above script will give a successful message as shown in the image below.

Make sure that while restoring database, the database is not in use, otherwise it will give an error of database in use. In the event of an error taking place, close all the connections and re-attempt to restore the database.

Mirror Backup of the file

It is quite a common practice to create an exact copy of the backup and store it to several places to deal with any catastrophes which might affect the place where the database is stored. Once a full backup is accomplished DBAs generally copy the database to another location in their network using a third party tools like robocopy or native DOS commands like xcopy.

In SQL Server 2005 and later versions, there is a Mirror command that makes a copy of the database backup to different locations while taking the original backup. The maximum limit of additional locations that can be specified with MIRROR clause is 3.

Mirrored backup can be taken in local computer system as well as in a local network. Let us now see two examples of mirror backup.

Example 1. Single File Backup to Multiple Locations using Mirror

If this command is being run for the first time, it is mandatory to use the WITH FORMAT clause; but for sub sequential runs it is not required. WITH FORMAT reinitializes the backup.

When checked in both the folders ‘SingleFile’ and ‘MirrorFile’, backup files are exactly the same files. As mentioned earlier, four mirror backup can be specified in total.

Example 2. Split File Backup to Multiple Locations using Mirror

We have earlier seen an example where we can have multiple split files of large database backup files. SQL Server Mirror functionality also supports backup of the split files.

All the mirror sets will need the same number of DISK clauses as the original backup media.

Mirrored database backup can be restored using the same method as the original backup. Mirrored backup is in fact an exact replica of the original backup.

Understanding the FORMAT Clause

The FORMAT clause is used to reinitiate a backup media. Although it is a very useful clause it should be used with caution. When the clause is used it erases everything present in backup media. I have noticed that some DBAs are confused while taking a backup on a local disk where they have SQL Server installed. They have a misconception that if the format command is used, it will erase the complete disk including the SQL Server installation. However, the fact is that SQL Server format clause is quite different from OS format. The effect of SQL Server format clause is limited to a folder or path specified in the DISK clause.

In our example, when the FORMAT clause is specified, it will format only folders like C:\Backup\MultiFile\ or C:\Backup\SingleFile.

Related Errors

Error 3010
Invalid backup mirror specification. All mirrors must have the same number of members.

This error can show up while taking a mirrored database backup along with a regular backup; and DISK and MIRROR TO DISK do not match accurately.

The following image demonstrates how the error takes place.

To fix the error, match the members of DISK and MIRROR TO DISK to each other.

Error 3215
Use WITH FORMAT to create a new mirrored backup set

This error can spring up when a new backup is initiated and an existing media header needs to be reset for all headers on the backup media. If there is already a backup on the media, it will display this error and prevent backup from being overwritten. To fix this error, use WITH FORMAT as shown in an earlier example.

Miscellaneous details about Backup and Restore

When no options are specified, BACKUP DATABASE takes only full backups. Before taking the first log backup, full database backup is necessary to take one full backup. Backups created on later versions of SQL Server cannot be restored to earlier versions of SQL Server. The user needs permissions of sysadmin or db_owner or db_backupoperator roles to perform backup operation.

Reference : Pinal Dave (http://blog.sqlauthority.com), DNS

What is SQL Azure?

In short, SQL Azure is simply a Microsoft branding change. SQL Services and SQL Data Services are now known as Microsoft SQL Azure and SQL Azure Database. There are a few changes, but fundamentally Microsoft’s plans to extend SQL server capabilities in cloud as web-based services remain intact. SQL Azure will continue to deliver an integrated set of services for relational databases. The reporting, analytics and data synchronization with end-users and partners also remains unchanged. This makes it most appealing to current users of SQL Server.

SQL Azure is going to be the Next Big Thing from Microsoft. It is just giving SQL Server a new way of doing operations it was doing for long time. Being on cloud, it keeps development relatively simple by keeping the heart of the programming almost the same. Additionally, SQL Azure keeps the goals of SQL Server, i.e. high availability, scalability and security in the core.

Developers can just start developing SQL Azure application locally using SQL Server Express version (http://www.microsoft.com/express/sql/download/), or the CTP version that will be available in August.

Read my complete article here.

Reference : Pinal Dave (http://blog.sqlauthority.com)

SQL Server Express is one of the most valuable products of Microsoft. Very often, I face many questions with regard to SQL Server Express. Today, we will be covering some of the most commonly asked questions.

Q: What is the cost of SQL Server Express?
A: SQL Server Express is a FREE product from Microsoft.

Q: Where can I find more details about SQL Server Express?
A: On official Microsoft Site: http://www.microsoft.com/express/sql/default.aspx

Q: Why should I use SQL Server Express when I have full version available?
A: Usually, I install only the license version product on my system. When I do not have to use all the features of SQL Server, I install SQL Server Express.

Q: What is the maximum size per database for SQL Server Express?
A: SQL Server Express supports a maximum size of 4 GB per database, which excludes all the log files. 4 GB is not a very large size; however, if database is properly designed and the tables are properly arranged in a separate database, this limitation can be resolved to a certain extent.

Q: Can MySQL be compared with SQL Server Express as both of them are free products?
A: Yes. Both are free and have their own space. However, thus far, I have never faced a situation wherein the task that can be accomplished by using MySQL is not accomplished by SQL Server Express.

Q: Does SQL Server have sufficient help available online?
A: Yes. There are so many online help resources available for SQL Server Express that user will find strongest community for any FREE product.

Let me give you quick list of the online help resources. Even though I took some time to build this reference list, I am sure that all of you will appreciate this and will share with others, which is worth the effort!

Overview

• SQL Server 2008 Product Overview
• SQL Server 2005 Express Edition Overview
• SQL Server Express Edition Comparison

Getting Started

Installation

• Downloading SQL Server2005 SP2 Express Edition
• Installation Requirements for SQL Server Express
• Upgrading from SQL Server 2005 Express Edition to Workgroup or Standard Editions
• Installing SQL Server Express Edition
• Building and shipping applications using SQL Server Express 2005

Quick Start

• Getting Started – How To: SQL Server Express
• Walkthrough: Creating an Application by Using SQL Server Express and Visual Web Developer 2005 Express
• Managing SQL Server Express Edition with Management Studio Express
• SQL Server 2005 Express Edition User Instances
• Using the sqlcmd Utility (SQL Server Express)
• How to manage the SQL Server Desktop Engine (MSDE 2000) or SQL Server 2005 Express Edition by using the osql utility
• Distributing SQL Server Express
• Reporting Services in SQL Server 2005 Express Edition with Advanced Services
• How to: Attach a Database File to SQL Server Express
• Replication in SQL Server Express
• Embedding SQL Server Express into Custom Applications

Misc

• View SQL Server Express Edition Case Studies
• SQL Server Express Developer Infocenter
• How to verify and change the system administrator password in MSDE or SQL Server 2005 Express Edition
• How SQL Server 2005 Express Edition determines the CPU count and uses the CPUs during processing
• How to connect to an instance of SQL Server Desktop Edition or of SQL Server 2005 Express Edition
• How to detect the status of the SQL Server Express service or start the SQL Server Express service by using Visual Basic or Visual C#
• How to perform full-text search related tasks in SQL Server 2005 Express Edition with Advanced Services

Blogs

• SQL Server Express – MSDN Forums
• Blogs: SQL Server Express WebLog

Webcasts

• 8-Part series of Webcasts over SQL Server Express Edition
• Using Service Broker in SQL Server 2005 Express Edition for Reliable Service-Oriented Architecture (SOA) Implementations (Level 300)
• Introducing SQL Server 2005 Express Edition: Your Smart Client Data Store (Level 200)
• TechNet Webcast: SQL Server 2005 Express Edition (Level 200)

Reference : Pinal Dave (http://blog.sqlauthority.com)

Simple-Talk.com has published my very first article on their site. This article is introducing Change Data Capture – the new concept introduced in SQL Server 2008. Change Data Capture records INSERTs, UPDATEs, and DELETEs applied to SQL Server tables, and makes a record available of what changed, where, and when, in simple relational ‘change tables’ rather than in an esoteric chopped salad of XML. These change tables contain columns that reflect the column structure of the source table you have chosen to track, along with the metadata needed to understand the changes that have been made.

Introduction to Change Data Capture (CDC) in SQL Server 2008

Please read my article and leave your valuable comments here. If you like the article do not forget to rate it.

Reference : Pinal Dave (http://blog.sqlauthority.com)

Posted in Database, Pinal Dave, SQL, SQL Authority, SQL Data Storage, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Utility, T SQL, Technology ]]> http://blog.sqlauthority.com/2009/08/15/sql-server-introduction-to-change-data-capture-cdc-in-sql-server-2008/feed/ 5 pinaldave http://blog.sqlauthority.com/2009/07/16/sql-server-four-different-ways-to-find-recovery-model-for-database/ http://blog.sqlauthority.com/2009/07/16/sql-server-four-different-ways-to-find-recovery-model-for-database/#comments Thu, 16 Jul 2009 01:30:26 +0000 pinaldave http://blog.sqlauthority.com/?p=5915 ]]>

Perhaps, the best thing about technical domain is that most of the things can be executed in more than one ways. It is always useful to know about the various methods of performing a single task. Today, we will observe four different ways to find out recovery model for any database.

Method 1

Right Click on Database >> Go to Properties >> Go to Option. On the Right side you can find recovery model.

Method 2

Click on the Database Node in Object Explorer. In Object Explorer Details, you can see the column Recovery Model.

Method 3

This is a very easy method and it gives all the database information in one script.

SELECT name AS [Database Name],
recovery_model_desc AS [Recovery Model]
FROM sys.databases
GO

Method 4

This method provides only one database at a time.

SELECT 'ADVENTUREWORKS' AS [Database Name],
DATABASEPROPERTYEX('ADVENTUREWORKS', 'RECOVERY')
AS [Recovery Model]
GO

My recommendation

Of all the above methods, I prefer Method 3. It is accurate and can be used in T-SQL code. Besides, I can use it for many other purposes as well.

I would like to know which one is your favorite method .

Reference : Pinal Dave (http://blog.SQLAuthority.com)

I maintain a spreadsheet of questions sent by users and from that I single out a topic to write and share my knowledge and opinion. Unless and until I find an issue appealing, I do not prefer to write about it, till the issue crosses the threshold. Today the question that crossed the threshold is – what is the difference between NORECOERY and RECOVERY when restoring database.

The fact is that one can easily go to MSDN and learn the difference, so I head myself to MSDN and read the difference. This is what the Book On Line suggests here.

NORECOVERY specifies that roll back not occur. This allows roll forward to continue with the next statement in the sequence.
In this case, the restore sequence can restore other backups and roll them forward.
RECOVERY (the default) indicates that roll back should be performed after roll forward is completed for the current backup.
Recovering the database requires that the entire set of data being restored (the roll forward set) is consistent with the database. If the roll forward set has not been rolled forward far enough to be consistent with the database and RECOVERY is specified, the Database Engine issues an error.

Book On Line has very clearly explained the same subject and provides succinct explanation of the difference.

In other words -

While doing RESTORE Operation if you restoring database files, always use NORECOVER option as that will keep database in state where more backup file are restored. This will also keep database offline also to prevent any changes, which can create itegrity issues. Once all backup file is restored run RESTORE command with RECOVERY option to get database online and operational.

It is also important to be acquainted with the restore sequence of how full database backup is restored.

First, restore full database backup, differential database backup and all transactional log backups WITH NORECOVERY Option. After that, bring back database online using WITH RECOVERY option.

Following is the sample Restore Sequence

RESTORE DATABASE DATABASE FROM full_database_backup WITH NORECOVERY;
RESTORE DATABASE DATABASE FROM differential_backup WITH NORECOVERY;
RESTORE LOG DATABASE FROM log_backup WITH NORECOVERY;
-- Repeat this till you restore last log backup
RESTORE DATABASE DATABASE WITH RECOVERY;

I hope now it is very clear to you all what is restore sequence and the difference between recovery options.

Reference : Pinal Dave (http://blog.SQLAuthority.com)

When it comes to storing images in database there are two common methods. I had previously blogged about the same subject on my visit to Toronto. With SQL Server 2008, we have a new method of FILESTREAM storage. However, the answer on when to use FILESTREAM and when to use other methods is still vague in community.

Let us look into two traditional methods first along with their advantage and disadvantages.

Method 1) Store image in filesystem and store pointer in database

This is quite an old method and you can find this implemented in many places, even though SQL Server 2005 has been released 5 years ago.
The advantage of this method is that there is no limit on the size of images file and it is the fastest way to retrieve images from system.
The drawback of this method is that application and database security acts separately and application/OS has to take backup for images.

Method 2) Store images in a database
This was introduced in SQL Server 2005 where images (binary data) can be stored in database.
The advantage of this method is same as the disadvantages of method 1, i.e. security and permissions.
The disadvantage of this method is same as the advantages of method 1, i.e. speed and maximum size is limited to 2 GB.

On observing Method 1 and Method 2, it is very clear that they are complementing each other but both are very powerful methods on their own.

Although both the methods are very good they have limitations, which together only they can provide. This is where FILESTREAM Storage comes into action.

FILESTREAM Storage system can store BLOB (Binary Large Object OBject) or images file, which is larger than 2 GB, and it can store them in database itself. It can be backed up just like regular database backup, and the security of the BLOB is maintained along with database application. After all this, it is as fast as filesystem. Now, this is what makes this superior to any other methods described earlier.

Summary: We can use FILESTREAM Storage to overcome traditional limitations of SQL Server storage of BLOB, varbinary or images.

Reference : Pinal Dave (http://blog.sqlauthority.com)

Standby servers - Standby Server is a type of server that can be brought online in a situation when Primary Server goes offline and application needs continuous (high) availability of the server. There is always a need to set up a mechanism where data and objects from primary server are moved to secondary (standby) server. This mechanism usually involves the process of moving backup from the primary server to the secondary server using T-SQL scripts. Often, database wizards are used to set up this process.

We will now glance at the various types of standby servers.

Hot Standby – Hot Standby can be achieved in SQL Server using SQL Server 2005 Enterprise Edition and the later enterprise versions. SQL Server 2005 has introduced Mirroring of database that can be configured for automatic failover in a disaster situation. In the case of synchronous mirroring database is replicated to both the servers simultaneously.  This is a little expensive but provides the best high availability. In this case, both primary and standby servers have same data all the time.

Warm Standby – In Warm Standby automatic failover is not configured. This is usually set up using Log Shipping or asynchronous mirroring. Sometimes warm standby is lagging by a few minutes or seconds, which results into loss of few latest updates when primary server fails and newer server needs to be failed over. Sometimes warm server that is lagging by a few transactions is brought back to the current state by applying recent transaction log.

Cold Standby – Code Standby servers need to be switched manually, and sometimes all the backups as well as the required OS need to be applied. Cold Standby  just physically replaces the previous server.

I am curious to know what do you all think about this these three types of standby servers. I am eager to know what kind of server setup you have at your workplace. If you can share these details, it will be very useful to all the readers. If I find your information interesting, I will create a new blog post with due credit to you.

Reference : Pinal Dave (http://blog.SQLAuthority.com)

This article revolves around a trivial yet common issue. There might be a set of people for whom the current topic might appear to be insignificant. But I have been asked this question innumerable times, particularly from   people who are frequenting using forums or have blog related to storage and highly availability, which instigated me to write this article.

Here goes this frequently asked question.

Question: Is it possible to restore database if one of the files of .mdf (primary data file) or .ndf (secondary data file) is missing?

Answer: In one word the answer is NO. All the .mdf and .ndf files are mandatory to attach or restore database successfully.  Even though  you have all the transactions stored in .ldf you will not be able to restore the database completely.

I hope this answer removes the cloud of doubt hovering over my targeted readers.

Reference : Pinal Dave (http://blog.sqlauthority.com)

Posted in Database, Pinal Dave, SQL, SQL Authority, SQL Backup and Restore, SQL Data Storage, SQL Error Messages, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology ]]> http://blog.sqlauthority.com/2009/04/10/sql-server-restore-or-attach-database-without-ndf-or-mdf-is-not-possible/feed/ 3 pinaldave http://blog.sqlauthority.com/2009/04/05/sql-server-mirrored-backup-and-restore-and-split-file-backup/ http://blog.sqlauthority.com/2009/04/05/sql-server-mirrored-backup-and-restore-and-split-file-backup/#comments Sun, 05 Apr 2009 01:30:04 +0000 pinaldave http://blog.sqlauthority.com/?p=4670 ]]>

Introduction

This article is based on a real life experience of the author while working with database backup and restore during his consultancy work for various organizations. We will go over the following important concepts of database backup and restore.

1. Conventional Backup and Restore
2. Spilt File Backup and Restore
3. Mirror File Backup
4. Understanding FORMAT Clause
5. Miscellaneous details about Backup and Restore

Conventional and Split File Backup and Restore

Just a day before working on one of the projects, I had to take a backup of one database of 14 GB. My hard drive lacked sufficient space at that moment. Fortunately, I had two 8 GB USB Drives with me. Now, the question was how to take a backup in two equal sizes, each of 7 GB, so I can fit them on each USB drive. Well, conventional backup takes one large backup in one file. However, SQL Server backup command can take backups in two or more split parts.

Read Complete Article here.

Reference : Pinal Dave (http://blog.SQLAuthority.com)

It goes without saying that Database Backup is the most important task for any Database Administrator (DBA). Naturally, large organizations always have a team of DBAs who execute Database Backup tasks. No matter how big or small an organization is, the importance of database backup remains the same across the board. It’s a common practice in several organizations to upload the backup to their remote location for additional safety. I totally vouch for this safety measure of having their additional backup on remote/satellite location. This redundancy comes in handy whenever a catastrophe of not having proper backup surfaces abruptly.

While I was searching online for a very simple solution for one of my clients, I came across a small-sized but feature-rich application from SqlBackupAndFTP.com. This practical application has been created by Pranas.NET (http://pranas.net) I have made extensive use of this tool for some time now and undoubtedly, this tool is very impressive by all standards!

To put it simply, SQLBackupAndFTP is MS SQL Server backup software. This tool performs several tasks such as running scheduled backups of SQL Server or SQL Server Express databases, zipping the backups, storing them on a network or on a FTP server, removing old backups, and finally, sending an e-mail confirmation on job’s success or failure. Besides, SQLBackupAndFTP Free is freeware, which is free from any spyware. Best of all, this ingeniously simple tool is extremely affordable for all. You just need to install it on the server and you can get up and running really fast.

Given below are some important tasks which this tool can perform using daily scheduler:
•    Backup SQL Server Database
•    Zip the backups
•    Encrypt the backups
•    FTP the backups to remove FTP server
•    Move file to local area network
•    Send final status of tasks in email.

Let us now see how we can take backup and move it to the desired folder.

Image 1: First, connect to the desired server.

Image 2: As you can see, all the settings are very easy as described in the following image. Pay attention to these very simple, one screen settings. From database selection to job scheduling, you can configure everything from this page itself.

Image 3: This screen describes all the steps that are being performed. User can easily view the status of all the jobs – either success or failure – on this page.

Image 4: The following screen displays the settings for advanced users who have to deal with large database.

Image 5: This screen displays email regarding final status of tasks, which is sent to the user after task completion.

Now, a question that might baffle your mind is – how this tool is better than maintenance tasks available in SQL Server. Well, here goes the answer. Maintenance tasks are easy to set up for backups; however, SQLBackupAndFTP have integrated solution for encryption, FTP and email which make it superior to maintenance tasks in every aspect.

I would like to present my unbiased view about this tool. At the same time, I want to give my readers a broad perspective about backup tools in general.  On comparing this tool with other backup tools I have experienced that it is not the fanciest tool to manage backups or check their health. This is one tool that smoothly performs the job in a few steps compared to native SQL Server backup, which takes numerous steps to execute the same job.

SQLBackupAndFTP is best suited for developers/DBAs who just want to ensure that they have schedule job that takes care of backup and moves them to appropriate place. In fact, it is ideal for any SQL Server database where backups need to be sent every day to a remote FTP server. It saves maintenance time on any SQL Server version. Besides, it is especially useful for SQL Server Express 2005 and SQL Server Express 2008, as they lack built in tools for backup.

This tool is compatible with almost all the known SQL Server versions. It works with SQL Server 2008 (all versions) and many of the previous versions.

While testing this tool, I noticed that there are few limitations. It does not support differential or transaction backups. I also found that this tool only works on local SQL Server instances and cannot connect to another SQL Server on LAN. When I contacted support, I came to know that they are planning to release its updated version in April 2009, which will not have any such limitations.

I strongly recommend this tool to all the DBAs. They must try it as it is absolutely free and does exactly what it promises. You can download your free copy of the tool from here.

Please share your experience about using this tool. I am eager to receive your feedback regarding this article.

Reference : Pinal Dave (http://blog.sqlauthority.com)

The most interesting thing about writing blog at SQLAuthority.com is follow up question. Just a day before I wrote article about SQL SERVER – Restore Master Database – An Easy Solution, right following it, I received email from user requesting reason for importance of backing up master database.

Master database contains all the system level information of server. Information about all the login account, system configurations and information required to access all the other database are stored in master database. If master database is damaged, it will be difficult to use any other database in SQL Server and that makes it most important database of the SQL Server.

Let us understand the important of the master database using an example. We will take example of SQL Server DBA and follow his timeline. Make sure to understand it correctly, as I have small question at the end of the timeline.

9:00 AM – DBA takes backup of the master database.
10:00 AM – DBA creates new Database named AfterMaster.
11:00 AM – DBA restores the master database backup taken at 9:00 AM.
12:00 PM – I have following two questions for the DBA :

Question 1) What will be the state of the database AfterMaster? If AfterMaster database will be in active state after restoring master database?
Question 2) What should be the next step after restoring master database?

Let us understand the answer of question.

Answer 1) Once master database is restored it will have no record of AfterMaster database in its system database and it will not recognize it.
Answer 2) If master database is restored from backup all the operation which are done after last master database backup should be repeated in order to bring SQL Server in the current operational state. In our case, the database files (ldf and mdf) of AfterMaster database will still exists on server. They should be reattached to the server. You can search about how to attach mdf and ldf file at Search@SQLAuthority.com.

It is clear from our example that master database contains user login, files, filegroups and server wide settings.

In summary, it is extremely important to take backup of the master database.

Reference : Pinal Dave (http://blog.SQLAuthority.com)

Just a day ago I have received following email from Siddhi and I found it interesting so I am sharing with all of you.

Previously I posted SQL SERVER – Find Row Count in Table – Find Largest Table in Database – T-SQL. Today we will look into the same issue but with some additional interesting detail.
We can find the row count using another system SP sp_spaceused. This SP gives additional information regarding disk space reserved on database as well. Well, when I ran the SP on AdventureWorks first time, I suspected that database SP is not providing me correct results.

After a bit investigating I found that it may be possible that due to any reason may be the usage on AdventureWorks database might not be updated. I ran same SP with additional param as shown below and it provided me updated information for the same. Once I ran the SP with @updateusage param, it updated the status of the database. When I ran it again next time without param it gave the same results.

The reason for above behavior is when dellocation of space happened in database (e.g. dropping table or truncating table) it does not release the used space right away. However, when @updateusage param is used database engine scans whole database and update the sapce usage in respective tables.
Let me know if you guys have any interesting observation like this.

Reference : Pinal Dave (http://blog.SQLAuthority.com)

Pro SQL Server 2005 Replication (Definitive Guide) (Hardcover)
by Sujoy Paul (Author)

Link to Amazon (This is not affiliate link)

Quick Review:
This is good book for any novice developer to start in the world of database replication implementation and maintenance. Replication is important part of highly availability and one book covers all the concept and methodology at one place.

Detail Review:
Replication is the process of sharing information so as to ensure consistency between redundant resources, such as software or hardware components, to improve reliability, fault-tolerance, or accessibility. Database replication can be used on many database management systems, usually with a master/slave relationship between the original and the copies. The master logs the updates, which then ripple through to the slaves. The slave outputs a message stating that it has received the update successfully, thus allowing the sending of subsequent updates.

This books talks about different replication types and methods. This book explains different scenarios where types of replication can be used. Sujoy Paul (SQL Server – MCP) explains the concept with many screenshots and simple examples. This book is not limited to replication types only but it also covers replication between heterogeneous databases and other objects.

Pros :

• Lots of screen shots
• Lots of explanation of how different procedures works
• Good coverage of different kind of replications
• Step by Step guidance
• Complete coverage of any methodology
• Truly useful to novice programmers

Cons:

• No discussion about potential errors can come across during replication process
• Some of the screen shots are hard to read (Apress should look into this matter)
• Some of the chapters are very blurry

Overall, this is great book for any novice developer who is beginning in the world of replication. Though this book covers many screenshots and material directly from Book On Line this is great collection of all the concept at any place. I have personally used this book when I was new DBA and have learned replication basics from this book.

Stars: 4 Stars

Summary: This a comprehensive single source of information will save lots of time as there is no need to go through multiple books to implement and maintain replication solutions.

Reference : Pinal Dave (http://blog.SQLAuthority.com)

SQL SERVER – Guidelines and Coding Standards complete List Download

Coding standards and guidelines are very important for any developer on the path of successful career. A coding standard is a set of guidelines, rules and regulations on how to write code. Coding standards should be flexible enough or should take care of the situation where they should not prevent best practices for coding. They are basically the guidelines that one should follow for better understanding.

The concept behind implementing coding standards and guidelines, is that the consistency and uniformity in programming so that if multiple people are working on the same code, it becomes easier to communicate, share with or understand each other’s work.

With the goal of promoting good coding standards and guidelines I have created document which can guide developers.

SQL SERVER – Guidelines and Coding Standards Part – 1

SQL SERVER – Guidelines and Coding Standards Part – 2

SQL SERVER – Guidelines and Coding Standards complete List Download

Reference : Pinal Dave (http://blog.SQLAuthority.com)

Download SQL Server 2008 Interview Questions and Answers Complete List

Interview is very important event for any person. A good interview leads to good career if candidate is willing to learn. I always enjoy interview questions and answers series. This is my very humble attempt to write SQL Server 2008 interview questions and answers. SQL Server is very large subject and not everything is usually asked in interview. In interview what matters the most is conceptual knowledge and learning attitude.

I have listed all the series in this post so that it can be easily downloaded and used. All the questions are collected and listed in one PDF which is here to download. If you have any question or if you want to add to any of the question please send me mail or write a comment.

SQL SERVER – 2008 – Interview Questions and Answers – Part 1

SQL SERVER – 2008 – Interview Questions and Answers – Part 2

SQL SERVER – 2008 – Interview Questions and Answers – Part 3

SQL SERVER – 2008 – Interview Questions and Answers – Part 4

SQL SERVER – 2008 – Interview Questions and Answers – Part 5

SQL SERVER – 2008 – Interview Questions and Answers – Part 6

SQL SERVER – 2008 – Interview Questions and Answers – Part 7

SQL SERVER – 2008 – Interview Questions and Answers – Part 8

Download SQL Server 2008 Interview Questions and Answers Complete List

Reference : Pinal Dave (http://blog.SQLAuthority.com)

SQL SERVER – 2008 – Interview Questions and Answers Complete List Download

What is Data Compression?

In SQL SERVE 2008 Data Compression comes in two flavors:

• Row Compression
• Page Compression

Row Compression

Row compression changes the format of physical storage of data. It minimize the metadata (column information, length, offsets etc) associated with each record. Numeric data types and fixed length strings are stored in variable-length storage format, just like Varchar.  (Read More Here)

Page Compression

Page compression allows common data to be shared between rows for a given page. Its uses the following techniques to compress data:

• Row compression.
• Prefix Compression. For every column in a page duplicate prefixes are identified. These prefixes are saved in compression information headers (CI) which resides after page header. A reference number is assigned to these prefixes and that reference number is replaced where ever those prefixes are being used.

Dictionary Compression.

Dictionary compression searches for duplicate values throughout the page and stores them in CI. The main difference between prefix and dictionary compression is that prefix is only restricted to one column while dictionary is applicable to the complete page.

What is use of DBCC Commands?

The Transact-SQL programming language provides DBCC statements that act as Database Console Commands for SQL Server.  DBCC commands are used to perform following tasks.

• Maintenance tasks on database, index, or filegroup.
• Tasks that gather and display various types of information.
• Validation operations on a database, table, index, catalog, filegroup, or allocation of database pages.
• Miscellaneous tasks such as enabling trace flags or removing a DLL from memory.

(Read More Here)

How to find tables without Indexes?

Run following query in Query Editor.

USE <database_name>;
GO
SELECT SCHEMA_NAME(schema_id) AS schema_name
,name AS table_name
FROM sys.tables
WHERE OBJECTPROPERTY(OBJECT_ID,'IsIndexed') = 0
ORDER BY schema_name, table_name;
GO

How to copy the tables, schema and views from one SQL Server to another?

There are multiple ways to do this.

1. “Detach Database” from one server and “Attach Database” to another server.
2. Manually script all the objects using SSMS and run the script on new server.
3. Use Wizard of SSMS. (Read More Here)

How to copy data from one table to another table?

There are multiple ways to do this.

1) INSERT INTO SELECT

This method is used when table is already created in the database earlier and data is to be inserted into this table from another table. If columns listed in insert clause and select clause are same, they are not required to list them.

2) SELECT INTO

This method is used when table is not created earlier and needs to be created when data from one table is to be inserted into newly created table from another table. New table is created with same data types as selected columns.

(Read More Here)

What is Catalog Views?

Catalog views return information that is used by the SQL Server Database Engine. Catalog Views are the most general interface to the catalog metadata and provide the most efficient way to obtain, transform, and present customized forms of this information. All user-available catalog metadata is exposed through catalog views.

What is PIVOT and UNPIVOT?

A Pivot Table can automatically sort, count, and total the data stored in one table or spreadsheet and create a second table displaying the summarized data. The PIVOT operator turns the values of a specified column into column names, effectively rotating a table.

UNPIVOT table is reverse of PIVOT Table. (Read More Here)

What is Filestream?

Filestream allows you to store large objects in the file system and have these files integrated within the database. It enables SQL Server based applications to store unstructured data such as documents, images, audios, videos etc. in the file system. FILESTREAM basically integrates the SQL Server Database Engine with New Technology File System (NTFS); it basically stores the data in varbinary (max) data type. Using this data type, the unstructured data is stored in the NTFS file system and the SQL Server Database Engine manages the link between the Filestream column and the actual file located in the NTFS. Using Transact SQL statements users can insert, update, delete and select the data stored in FILESTREAM enabled tables.

What is Dirty Read ?

A dirty read occurs when two operations say, read and write occurs together giving the incorrect or unedited data. Suppose, A has changed a row, but has not committed the changes. B reads the uncommitted data but his view of the data may be wrong so that is Dirty Read.

What is SQLCMD?

sqlcmd is enhanced version of the isql and osql and it provides way more functionality than other two options. In other words sqlcmd is better replacement of isql (which will be deprecated eventually) and osql (not included in SQL Server 2005 RTM). sqlcmd can work two modes – i) BATCH and ii) interactive modes. (Read More)

What is Aggregate Functions?

Aggregate functions perform a calculation on a set of values and return a single value. Aggregate functions ignore NULL values except COUNT function. HAVING clause is used, along with GROUP BY, for filtering query using aggregate values.

Following functions are aggregate functions.

AVG, MIN, CHECKSUM_AGG, SUM, COUNT, STDEV, COUNT_BIG, STDEVP, GROUPING, VAR, MAX, VARP (Read More Here )

What do you mean by Table Sample?
TABLESAMPLE allows you to extract a sampling of rows from a table in the FROM clause. The rows retrieved are random and they are not in any order. This sampling can be based on a percentage of number of rows. You can use TABLESAMPLE when only a sampling of rows is necessary for the application instead of a full result set. (Read More Here)

What is Row_Number()?
ROW_NUMBER() returns a column as an expression that contains the row’s number within the result set. This is only a number used in the context of the result set, if the result changes, the ROW_NUMBER() will change.

What are Ranking Functions?

Ranking functions return a ranking value for each row in a partition. All the ranking functions are non-deterministic. Different Ranking functions are:

ROW_NUMBER () OVER ([<partition_by_clause>] <order_by_clause>)
Returns the sequential number of a row within a partition of a result set, starting at 1 for the first row in each partition.

RANK () OVER ([<partition_by_clause>] <order_by_clause>)
Returns the rank of each row within the partition of a result set.

DENSE_RANK () OVER ([<partition_by_clause>] <order_by_clause>)
Returns the rank of rows within the partition of a result set, without any gaps in the ranking. (Read More Here )

What is the difference between UNION and UNION ALL?

UNION
The UNION command is used to select related information from two tables, much like the JOIN command. However, when using the UNION command all selected columns need to be of the same data type. With UNION, only distinct values are selected.

UNION ALL
The UNION ALL command is equal to the UNION command, except that UNION ALL selects all values.

The difference between Union and Union all is that Union all will not eliminate duplicate rows, instead it just pulls all rows from all tables fitting your query specifics and combines them into a table. (Read More Here)

What is B-Tree?

The database server uses a B-tree structure to organize index information. B-Tree generally has following types of index pages or nodes:

• root node: A root node contains node pointers to branch nodes which can be only one.
• branch nodes: A branch node contains pointers to leaf nodes or other branch nodes which can be two or more.
• leaf nodes: A leaf node contains index items and horizontal pointers to other leaf nodes which can be many.

© Copyright 2000-2009 Pinal Dave. All Rights Reserved. SQLAuthority.com

Reference : Pinal Dave (http://blog.SQLAuthority.com)

SQL SERVER – 2008 – Interview Questions and Answers Complete List Download

3) Questions of SQL SERVER 2008

What are the basic functions for master, msdb, model, tempdb and resource databases?

The master database holds information for all databases located on the SQL Server instance and is theglue that holds the engine together. Because SQL Server cannot start without a functioning masterdatabase, you must administer this database with care.

The msdb database stores information regarding database backups, SQL Agent information, DTS packages, SQL Server jobs, and some replication information such as for log shipping.

The tempdb holds temporary objects such as global and local temporary tables and stored procedures.

The model is essentially a template database used in the creation of any new user database created in the instance.

The resoure Database is a read-only database that contains all the system objects that are included with SQL Server. SQL Server system objects, such as sys.objects, are physically persisted in the Resource database, but they logically appear in the sys schema of every database. The Resource database does not contain user data or user metadata.

What is Service Broker?

Service Broker is a message-queuing technology in SQL Server that allows developers to integrate SQL Server fully into distributed applications. Service Broker is feature which provides facility to SQL Server to send an asynchronous, transactional message. it allows a database to send a message to another database without waiting for the response, so the application will continue to function if the remote database is temporarily unavailable. (Read More Here)

Where SQL server user names and passwords are stored in SQL server?

They get stored in System Catalog Views sys.server_principals and sys.sql_logins.

What is Policy Management?

Policy Management in SQL SERVER 2008 allows you to define and enforce policies for configuring and managing SQL Server across the enterprise. Policy-Based Management is configured in SQL Server Management Studio (SSMS).  Navigate to the Object Explorer and expand the Management node and the Policy Management node; you will see the Policies, Conditions, and Facets nodes. (Read More Here)

What is Replication and Database Mirroring?

Database mirroring can be used with replication to provide availability for the publication database. Database mirroring involves two copies of a single database that typically reside on different computers. At any given time, only one copy of the database is currently available to clients which are known as the principal database. Updates made by clients to the principal database are applied on the other copy of the database, known as the mirror database. Mirroring involves applying the transaction log from every insertion, update, or deletion made on the principal database onto the mirror database.

What are Sparse Columns?

A sparse column is another tool used to reduce the amount of physical storage used in a database. They are the ordinary columns that have an optimized storage for null values. Sparse columns reduce the space requirements for null values at the cost of more overhead to retrieve nonnull values. (Read More Here)

What does TOP Operator Do?

The TOP operator is used to specify the number of rows to be returned by a query. The TOP operator has new addition in SQL SERVER 2008 that it accepts variables as well as literal values and can be used with INSERT, UPDATE, and DELETES statements.

What is CTE?

CTE is an abbreviation Common Table Expression. A Common Table Expression (CTE) is an expression that can be thought of as a temporary result set which is defined within the execution of a single SQL statement. A CTE is similar to a derived table in that it is not stored as an object and lasts only for the duration of the query. (Read More Here)

What is MERGE Statement?
MERGE is a new feature that provides an efficient way to perform multiple DML operations. In previous versions of SQL Server, we had to write separate statements to INSERT, UPDATE, or DELETE data based on certain conditions, but now, using MERGE statement we can include the logic of such data modifications in one statement that even checks when the data is matched then just update it and when unmatched then insert it. One of the most important advantages of MERGE statement is all the data is read and processed only once.  (Read More Here)

What is Filtered Index?

Filtered Index is used to index a portion of rows in a table that means it applies filter on INDEX which improves query performance, reduce index maintenance costs, and reduce index storage costs compared with full-table indexes. When we see an Index created with some where clause then that is actually a FILTERED INDEX.

Which are new data types introduced in SQL SERVER 2008?

The GEOMETRY Type: The GEOMETRY data type is a system .NET common language runtime (CLR) data type in SQL Server. This type represents data in a two-dimensional Euclidean coordinate system.

The GEOGRAPHY Type: The GEOGRAPHY datatype’s functions are the same as with GEOMETRY. The difference between the two is that when you specify GEOGRAPHY, you are usually specifying points in terms of latitude and longitude.

New Date and Time Datatypes: SQL Server 2008 introduces four new datatypes related to date and time: DATE, TIME, DATETIMEOFFSET, and DATETIME2.

• DATE: The new DATE type just stores the date itself. It is based on the Gregorian calendar and handles years from 1 to 9999.
• TIME: The new TIME (n) type stores time with a range of 00:00:00.0000000 through 23:59:59.9999999. The precision is allowed with this type. TIME supports seconds down to 100 nanoseconds. The n in TIME (n) defines this level of fractional second precision, from 0 to 7 digits of precision.

• The DATETIMEOFFSET Type: DATETIMEOFFSET (n) is the time-zone-aware version of a datetime datatype. The name will appear less odd when you consider what it really is: a date + a time + a time-zone offset. The offset is based on how far behind or ahead you are from Coordinated Universal Time (UTC) time.

• The DATETIME2 Type: It is an extension of the datetime type in earlier versions of SQL Server. This new datatype has a date range covering dates from January 1 of year 1 through December 31 of year 9999. This is a definite improvement over the 1753 lower boundary of the datetime datatype. DATETIME2 not only includes the larger date range, but also has a timestamp and the same fractional precision that TIME type provides

What are the Advantages of using CTE?

• Using CTE improves the readability and makes maintenance of complex queries easy.
• The query can be divided into separate, simple, logical building blocks which can be then used to build more complex CTEs until final result set is generated.
• CTE can be defined in functions, stored procedures, triggers or even views.
• After a CTE is defined, it can be used as a Table or a View and can SELECT, INSERT, UPDATE or DELETE Data.

© Copyright 2000-2009 Pinal Dave. All Rights Reserved. SQLAuthority.com

Reference : Pinal Dave (http://blog.SQLAuthority.com)