SQL Server 2016 SP1 is released as announced by Microsoft. It comes with a bunch of new features and enhancements as a result of customer and community feedback. In this article, I will introduce you to these new features and enhancements.
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When creating a database, SQL Server maps this database with minimum two operating system files; the database data file MDF and the database log file LDF. Logically, the database data files are created under a collection set of files that simplifies the database administration, this logical file container is called the Filegroup. Database data files can come in two types, the Primary data files that contains metadata information for the database and pointers to the other database files in addition to the data, where each database should have only one Primary data file and the optional Secondary files to store data only. The basic storage unit in SQL Server is the Page, with each page size equal to 8KB. And each 8 pages with 64KB size called Extent.
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SQL Server table partitioning is a great feature that can be used to split large tables into multiple smaller tables, transparently. It allows you to store your data in many filegroups and keep the database files in different disk drives, with the ability to move the data in and out the partitioned tables easily. A common example for tables partitioning is archiving old data to slow disk drives and use the fast ones to store the frequently accessed data. Table partitioning improves query performance by excluding the partitions that are not needed in the result set. But table partitioning is available only in the Enterprise SQL Server Edition, which is not easy to upgrade to for most of small and medium companies due to its expensive license cost.
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The Cardinality Estimator is a SQL Server Query Processor component that is responsible for predicting the number of rows that the query will return. This estimation of the number of rows in addition to the SQL Server statistics will be used by the SQL Server Query Optimizer to create the optimal and the most accurate execution plan for your query that has the lowest processing cost to execute.
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SQL Server 2016 introduces a new set of configurations that can be applied at the database level to control its performance and behavior. These configurations were previously applicable only at the SQL instance level before version SQL Server 2016, With the ability to configure settings at the database level, many databases that are hosted in the same instance can now be isolated from each other, with each database has its own customized configurations. The database level configurations allow us also to set different database configurations for the Always On Availability Groups primary and secondary databases to meet the different types of workloads.
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SQL Server tries always to generate the most optimized execution plan for each stored procedure the first time that the stored procedure is executed. The SQL Server Engine looks at the stored procedure passed parameter values when compiling the stored procedure, the first execution, in order to create the optimal plan including the parameters and keep that plan for future use in the plan cache. This parameter analysis process is called the Parameter Sniffing.
Read more »Dynamic Data Masking is a new security feature introduced in SQL Server 2016 that limits the access of unauthorized users to sensitive data at the database layer.
As an example of the need for such a feature is allowing the applications developers to access production data for troubleshooting purposes and preventing them from accessing the sensitive data at the same time, without affecting their troubleshooting process. Another example is the call center employee who will access the customer’s information to help him in his request, but the critical financial data, such as the bank account number or the credit card full number, will be masked to that person.
Read more »My name is Ahmad Yaseen and I am a senior SQL Server database administrator at Aramex International Company for more than six years, where I started building my experience in the SQL Server administration field. Being a SQL Server Database administrator in such big company is not that easy, as the difficulties that you may face is not only at the beginning. What makes the DBA job special is that it is a very deep job, in which you will learn new things, have to solve new problems, fall in strange situations and be under pressure every day, but it is an interesting job for me.
Read more »SQL Server 2016 came with many new features and enhancements for existing ones, that concentrate on the aspect of SQL Server security. One of the new security features introduced in SQL Server 2016 is Row-Level Security. This feature allows us to control access deeply into the rows level in the database table, based on the user executing the query. This is done within the database layer, in complete transparency to the application process, without the need to manage it with complex coding at the application layer.
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SQL Server 2016 introduces a new type of table that is designed to keep the full history of data changes, where row validity is managed by the system. This new table type is called a System-Versioned Temporal Table. In earlier SQL Server versions, user tables would enable you to hold only the most recent copy of the row, without being able to query the value before the UPDATE or DELETE operations. Using a Temporal Table, you will be able to query the recent state of the row as usual, in addition to the ability to query the full history of that row, which is fully managed by the SQL Server Engine, as you can’t define the rows validity period explicitly.
Read more »When a new row is inserted or an existing one is updated in your database, the SQL Server Database Engine will keep that change in the buffer pool in the memory first, without applying each change directly to the database files for IO performance reasons. These data pages located in the buffer pool and not reflected yet to the database files are called Dirty Pages. The SQL Server Database Engine uses a special kind of processes to write these dirty pages to the data and log database files periodically. These processes are called Checkpoints. The Checkpoint creates a mark that is used by the SQL Server Database Engine to redo any transaction that is committed, written to the database transaction log file without reflecting the data changes to the data files due to an unexpected shutdown or crash. Also, this recovery point that is created by the Checkpoint will be used to roll back any data changes associated with uncommitted transaction, by reversing the operation written in the transaction log file. In this way the SQL Server Engine will guarantee the database consistency. The time that is taken by the SQL Server Database Engine to redo and undo the transactions is called the Recovery Time. All information about the Checkpoints will be written to the database boot page to identify till which point the database files are synchronized with the buffer pool when the system wakes up after crash or shutdown.
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SQL Server 2008 introduces a new column attribute that is used to reduce the storage consumed by NULL values in the database tables. This feature is known as Sparse Columns. Sparse Columns work effectively in the case of the columns with high proportion of NULL values, as SQL Server will not consume any space storing the NULL values at all, which helps in optimizing the SQL storage usage.
Read more »SQL Server Management Studio a graphical interactive that allows you to interact with the databases hosted on your servers. SSMS provides you with the ability to write, edit, execute, analyze and monitor your SQL queries. It also helps database administrators answer important questions about the SQL query performance, such as why a query is slow or why an index is not used. The answer to these questions can be found simply by tracking the Query Execution Plan.
Read more »SQL Server Trace Flags are special switches that are used to customize and control specific behaviors of the SQL Server Engine. Trace Flags can be defined in two forms; Session Trace Flags that are activated and visible at the current connection level only, and Global Trace Flags that are enabled and visible at the SQL Server Instance level and applied to all connecting sessions in that SQL Server. Global Trace Flags should be enabled globally in order to take effect, where some Trace Flags that can be either Global or Session Trace Flags can be enabled in the appropriate scope, and its effect will appear on the defined level.
Read more »SQL Server Query Store is a new feature introduced in SQL Server 2016 that is used to automatically and asynchronously capture query execution history, statistics and plans, with minimal impact to overall SQL Server Performance. The Query Store feature makes performance problem troubleshooting simple; you can view the query execution plans changes and compare its performance to decide which execution plan the SQL Server Query Optimizer should use for that query.
Read more »SQL Server Resource Governor was introduced in SQL Server 2008. This feature is used to control the consumption of the available resources, by limiting the amount of the CPU, Memory and IOPS used by the incoming sessions, preventing performance issues that are caused by resources high consumption.
Read more »SQL Server 2016 introduced officially on the 1st of June 2016. It comes with many new features such as Query Store that maintains the execution plans history for the queries with its performance data in order to detect any slowness in the query caused by the new plans, so that the administrator can force the use of the better old plan.
Read more »SQL Server Policy-Based Management was introduced in SQL Server 2008, to make it easy for database administrators to define and enforce SQL Server best practices and company standards in the form of policies. This feature is available in both Enterprise and Standard SQL Server Editions.
Read more »SQL Server Network Configuration involves enabling the protocols that manage the connection to the SQL Server and configuring the available options for these network protocols. It also provides the means to encrypt the communication between the SQL Server instance and the client applications and hide the SQL Server instance from being browsed. SQL Server Network Configuration can be managed using the SQL Server Configuration Manager tool.
Read more »A common activity when writing T-SQL queries is connecting to local databases and processing data directly. But there will be situations in which you need to connect to a remote database that is located in a different instance in the same server or in a different physical server, and process its data in parallel with the local data processing.
SQL Server provides us with four useful methods to connect to the remote database servers, even other database server types, and query its data within your T-SQL statement. In this article, we will discuss these four methods and how to use it to query remote SQL Server databases.
Read more »SQL Server provides two ways to authenticate users; SQL Server Authentication, which requires a predefined username and password to connect to the SQL Server, and Windows Authentication, in which SQL Server trusts the windows integrated user. The server level user that is authenticated to connect to the SQL Server is called a Server Login. This login should be mapped to a database user and granted permissions at the database level in order to access the database and be able to perform the authorized tasks. The relationship between the Server login and the database user in addition to the database metadata stored in the master system database draw up the dependencies between the SQL Server databases the server-level resources.
Read more »SQL Server databases consist of two physical files types; the data file in which the data and the database objects such as tables and indexes are stored, and the transaction log file in which SQL Server stores records for all transactions performed on that database.
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By default, SQL Server stores data logically in the tables as rows and columns, which appear in the result grid while retrieving data from any table and physically in the disk in the row-store format inside the data pages. A new data store mechanism introduced in SQL Server 2012, based on xVelocity in-memory technology, in which the data is stored in the column-store data format. This data store mechanism called the Columnstore index.
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In some cases, as a DBA, you are requested to copy the schema and the content of specific tables from a database to another one in the same instance or in a different SQL instance, such as copying specific tables from a production database to a DEV one for testing or troubleshooting purposes.
SQL Server offers a lot of methods that can be used to perform table’s data and schema copy process. In order to go through each one of these methods, we will consider the below scenario:
SQL Server Views are virtual tables that are used to retrieve a set of data from one or more tables. The view’s data is not stored in the database, but the real retrieval of data is from the source tables. When you call the view, the source table’s definition is substituted in the main query and the execution will be like reading from these tables directly.
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