The skills of writing different types of SQL Server queries require you to have good knowledge in the SQL Server T-SQL language. T-SQL stands for Transact Structure Query Language, which is a database procedural programming language that is extending the SQL language for Microsoft SQL Server RDBMS product. Read More
Introduction to SQL Server Indexes
Microsoft SQL Server is considered as one of the relational database management systems (RDBMS), in which the data is logically organized into rows and columns that are stored in data containers called tables. Physically, the tables are stored as 8 KB pages that can be organized into Heap or B-Tree Clustered tables. In the Heap table, there is no sorting order that controls the order of the data inside the data pages and the sequence of pages within that table, as there is no Clustered index defined on that table to enforce the sorting mechanism. If a Clustered index is defined on one column of the group of table columns, the data will be sorted inside the data pages based on the values of the Clustered index key columns, and the pages will be linked together based on these index key values. This sorted table is called a Clustered table.
When testing the functionality of your application or the performance of a specific stored procedure or an ad-hoc query in the development environment, you need to have data stored in your development databases typical or similar to the data stored in the production databases. This is because the performance of a query that is processing 50 records will be different from the performance of the same query that is processing 50M rows. Restoring a copy of the production database to the development database server for testing purposes is not always a valid option, due to the critical data that is stored in these databases and should not be open for all employees to see, unless you are developing a new application and there is no production database yet.
The best and most secure alternative is to fill the development database tables with testing data. Test data generation is useful for testing the performance of the application or a new functionality without changing the production data. There is no single straight-forward way to generate test data that will fit all scenarios, especially when you need to generate large amount of data to test the performance of complex queries and transactions in which you should cover all possible combinations of testing cases. Read More
Starting from SQL Server 2008, Microsoft introduced a new feature in the SQL Server Management Studio that helps the database developers and the database administrators writing the T-SQL commands faster by reducing the typing effort and providing a quick access to the syntax information via listing all available database objects with their properties. This feature is called IntelliSense.
SQL Server provides us with different solutions to replicate or archive a database table or tables to another database, or the same database with different names. As an SQL Server Developer or Database Administrator, you may face situations when you need to check that the data in these two tables are identical, and if, by mistake, the data is not replicated between these two tables, you need to synchronize the data between the tables. In addition, if you receive an error message, that breaks the data synchronization or replication process, due to schema differences between the source and destination tables, you need to find an easy and fast way to identify the schema differences, ALTER the tables to make the schema identical in both sides and resume the data synchronization process. Read More
Before going through the Forwarded Records performance issue and resolving it, we need to review the structure of the SQL Server tables.
Table Structure Overview
In SQL Server, the fundamental unit of the data storage is the 8-KB Pages. Each page starts with a 96-byte header that stores the system information about that page. Then, the table rows will be stored on the data pages serially after the header. At the end of the page, the row offset table, that contains one entry for each row, will be stored opposite to the sequence of the rows in the page. This row offset entry shows how far the first byte of that row is located from the start of the page.
In my previous article, Microsoft SQL Operations Studio: Understanding and Installation, we discussed deeply the need for a new SQL Server development and administration graphical user interface tool that can replace the default SQL Server user interface tool, the SQL Server Management Studio. We discussed deeply the new features and the advantages of SQL Operations Studio over the SQL Server Management Studio tool and how to download and install it to the Windows machine.
In this article, we will see the different configuration of the SQL Operations Window and how we can perform our daily tasks with it.
SQL Server Management Studio is considered as the default integrated graphical user interface tool that has been used for many years to configure, manage, monitor and administrate the SQL Server instances hosted on the local machines, on remote servers or in the cloud by all SQL Server administrators and developers. It provides us with editing, debugging and deploying environment for many languages including T-SQL, XML, MDX and DMX languages. Due to the fact that Microsoft SQL Server can be installed now on the Linux platform, and that the SQL Server Management Studio tool is not compatible with any operating system outside Microsoft Windows, the need for a new cross-platform graphical user interface appears.
The SQL Server trigger is a special type of stored procedures that is automatically executed when an event occurs in a specific database server. SQL Server provides us with two main types of triggers: the DML Triggers and the DDL triggers. The DDL triggers will be fired in response to different Data Definition Language (DDL) events, such as executing CREATE, ALTER, DROP, GRANT, DENY, and REVOKE T-SQL statements. The DDL trigger can respond to the DDL actions by preventing these changes from affecting the database, perform another action in response to these DDL actions or recording these changes that are executed against the database. Read More
Table indexing strategy is one of the most important performance tuning and optimization keys. In SQL Server, the indexes (both, clustered and nonclustered) are created using a B-tree structure, in which each page acts as a doubly linked list node, having an information about the previous and the next pages. This B-tree structure, called Forward Scan, makes it easier to read the rows from the index by scanning or seeking its pages from the beginning to the end. Although the forward scan is the default and heavily known index scanning method, SQL Server provides us with the ability to scan the index rows within the B-tree structure from the end to the beginning. This ability is called the Backward Scan. In this article, we will see how this happens and what are the pros and cons of the Backward scanning method. Read More