SQL Server Central. Microsoft SQL Server tutorials, training forum. There are a number of different ways that you can host SQL Server. What version of SQL Server do I have This unofficial build chart lists all of the known Service Packs SP, Cumulative Updates CU, patches, hotfixes and other. If you are using SQL Server 2008 Enterprise Edition or SQL Server 2008 R2 or SQL Server 2012 Standard and Enterprise Editions, you can even take benefits of the. Windows Server 2003 is a server operating system produced by Microsoft and released on April 24, 2003. It was a successor of Windows 2000 Server and incorporated some. Indexed materialized views in Microsoft SQL Server SQL Server Consulting April 29, 2011 at 641 pm. It is most amazing how SQL can adjust in. Views are a valuable tool for the SQL Server Developer, because they hide complexity and allow for a readable style of SQL expression. Dss To Wav Converter. They arent there for reasons. RDS SQL Server, for example, uses SQL Server within AWS as a simple database service, much like a more versatile alternative to My. SQL. Obviously, it is a compromise, in that you lose many of the extras beyond the database. Laerte Junior answers those questions about RDS that people seem to assume you know the answers to, but which you may be too shy to ask. Clustered and non clustered indexes in SQL Server. Overview When do I use a clustered index vs. This is somewhat of a tough question to answer. By submitting your personal information, you agree that Tech. Target and its partners may contact you regarding relevant content, products and special offers. You also agree that your personal information may be transferred and processed in the United States, and that you have read and agree to the Terms of Use and the Privacy Policy. Im going to give is the age old standard database administrators answer It depends. There are numerous factors into the when and where of index placement. The good news is that there are only two options per s. The bad news is that there are fairly esoteric gains and limitations to both. The basics. Im not going to go into great detail here about how indexes function at their lowest level. Whole books have been written on that subject, and there are folks who solely specialize in the placement of indexes. Just know this according to the powers that be a clustered index is better than no index at all. The biggest difference between a clustered index and a non clustered index is that when you use a clustered index, the section of the table that comprises the index has its data pages linked differently from those data pages comprising a non clustered index. In SQL Server 2. 00. B Tree. Whats being referred to here is that a table with non clustered index is generally referred to as a heap. A B Tree or Balanced Tree is the general structure that clustered indexes take. Theyre kind of like a telephone book. We know that in SQL Server 2. K data pages. There are also eight different kinds of them too. Index data pages have pointers to smaller subsets of data, which have pointers to even smaller subsets of data, etc. For instance, when you open the phone book, what do you see in the upper left or right hand corners of the opposing pages You see the range that the page covers. Thats how B Trees function. So whats the difference here When a clustered index is applied, the data at the leaf level contains the actual data pages where youll find the data being searched on. In a non clustered index, the data pages at the leaf level merely have pointers to more data pages containing the actual data being searched upon. This being the case, the data pages at the leaf level in a clustered index are only ordered one way, and in order. For instance, if you have a column with an IDENTITY constraint applied to it as well as a clustered index, the numbers comprising the IDENTITY constraint will always be in order. Yet, that is not to say always contiguous, as you can DELETE rows. But they will always be in order. This makes for very fast searching, especially when using this scenario for something like order or invoice IDs. The Caveats. The trade offs involved with using clustered or non clustered indexes are a world of give and take. One of the most important things that I was ever taught is that since clustered indexes keep all data within them at the leaf level of the B Tree, any modifications to the data require a rearranging of the data pages. This means, if you add a clustered index to a table that is heavily inserted, updated, or deleted, you will probably need to rebuild or de fragment the index more often than when a non clustered index is used. This is due to all of the data page movement that occurs. Once again, the gain you receive is faster reads of the data, due to the orderly fashion in which the data is laid out. The other major difference is that you only get one clustered index per table. You can apply 2. 49 non clustered indexes. Keep in mind that although you only get one clustered index per table, it does not solely need to be comprised of a single column. You are more than welcome to apply that index to multiple columns creating a covering index. Think about the search criteria on the table What is being queriedIf youre querying multiple columns at the same time, a covering index may be your answer. Another fine compromise is evaluating what is being queried, and then applying a clustered index to the column most commonly used in WHERE clauses. Then apply a covering non clustered index to the remaining columns in the SELECT statements. Lastly there is also the option to use an Indexed view. This is essentially Microsofts implementation of materialized views as seen in other platforms. Be aware when you apply an index to a view, you are now creating a new database object, whereas the result sets coming from a non indexed view are only durable as long as the session is open, and are completely virtual. An Indexed view is not. The Best PracticesTest, test, test. There are numerous tools at your disposal in SQL Server 2. One of them is the Display Estimated Execution Plan. You can find the Display Estimated Execution Plan in the Query Menu at the top of the SQL Server Management Studio, by pressing CTRL L or on the toolbar above the query pane in SSMS. By implementing this tool the SQL Server is telling you what it thinks it might do. Dont fight it. Its instincts are usually right. Display the estimated execution plan for a query prior to applying an index, and then apply an index to see what improvements in performance are made with your choice of index. You can also implement the use of the Actual Execution plan as well. This too is found in the Query menu, by pressing CTRL M, or by a button on the toolbar. Another excellent tool to help in your choices of tools to implement is the Database Engine Tuning Advisor found under the Tools menu. Not only can this tool help with choosing proper index implementation, it can also help you with the decision to implement one of the most sought after new features of SQL Server 2. Partitioning. But keep in mind that partitioning is only available for use in production systems in SQL Server 2. Enterprise Edition, and there is an additional cost associated with that version of the product as compared to Standard Edition. One last best practice to consider when looking to improve the performance of indexes, is whether or not to move an index structure to a different storage array. If you currently have all of your database objects in a single or even multiple file groups on the same array, substantial increases in performance have been obtained by migrating index structures to RAID 1 arrays. I personally have used this technique with great success. Closing In short, there are no hard and fast rules here. If you display the actual execution plan on a table that has just had an index applied to it and the query plan still shows a table scan is being executed, you have some choices You can keep the index on the query and hope the statistics improve over time. You can remove the index. You can spend more time working on the query itself. Do not be discouraged to try new things in order to increase the quality of your database performance. Unfortunately the business has a habit of convincing themselves that databases are relatively static, and sometimes they dont quite understand What happened It worked great last week The more data you put into a database, it changes. The more functionality you add to a database, it changes. The more you take out, it changes. With these changes come the need to reevaluate indexing structures, and performance tuning and optimization opportunities.