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    SQL Server, when capitalized, is a relational database management system (RDBMS) offered by Microsoft. When speaking more generically, a SQL server is a database management system (DBMS) that can respond to queries from client machines formatted in the SQL language. This article focuses on defining the features and functionalities of Microsoft SQL Server.

    What is SQL Server? 

    A relational database management system is software used to store, manage, query, and retrieve data in a relational database. It creates an interface between users, applications, and the database, and it also provides administrative functions for managing data access, storage, and performance.

    Microsoft SQL Server Logo

    The SQL Server is built on SQL, a programming language that supports relational databases. It is connected to T-SQL (Transact-SQL), an extension of the SQL language. T-SQL offers all the features of SQL but adds proprietary programming constructs.

    For more than 20 years, SQL Server worked solely in the Windows environment. In 2016, it was made available on Linux

    There are five editions of SQL Server: Standard, Web, Enterprise, Developer, and Express. These are aimed at different audiences and workloads—from single-machine applications to large internet-facing applications with many concurrent users.

    What does SQL Server do?

    The SQL Server is designed to manage and store information. Its primary function is storing and retrieving data as requested by users and other software applications. It supports different business intelligence operations, transaction processing, and analytics operations.

    The main component of this solution is the SQL Server Database Engine. It has two major components: Storage Engine and Relational Engine. The Storage Engine manages databases, while the Relational Engine processes commands and queries.

    What are SQL Server’s key features?

    Intelligent Query Processing 

    When SQL Server gets a query, it optimizes a query plan via calculations, like whether to use an index. The relational database management system’s query plans depend on what will happen at run time when a query executes. 

    Intelligent Query Processing (IQP) optimizes query plans automatically. As data changes, queries still run as fast as possible. Performance improvements happen when users upgrade to SQL Server 2019 and compatibility level 150 due to added intelligence in the query optimizer.

    Accelerated Database Recovery

    This is a database engine feature that significantly improves database availability, especially during long-running transactions. It redesigns the SQL Server database engine recovery process. 

    This feature is only found in SQL Server 2019 and gets databases online faster by removing some of the bottlenecks in the older recovery process. And it doesn’t just work for crash scenarios; it also works for failover clusters and redoes operations within Availability Groups.

    Always Encrypted with Secure Enclaves

    This feature was also introduced in SQL Server 2019 and allows the database layer to form a secure area in memory to decrypt encrypted data to plaintext. The feature lets users protect sensitive data, such as national identification numbers or credit card numbers, stored in SQL Server databases. 

    Users can encrypt sensitive data inside client applications without revealing the encryption keys to the Database Engine. Always Encrypted with Secure Enclaves protects data confidentiality from privileged users like system administrators.

    Memory-Optimized TempDB Metadata

    This new feature in SQL Server 2019 effectively manages and simplifies resource contention. It gives users greater flexibility to handle and scale heavy TempDB workloads. The feature boosts system performance if performance issues are caused by metadata contention or heavy read-write on the TempDB. Some of the metadata that can affect TempDB-heavy systems relies completely on memory and can be optimized for RAM access.

    Query Store 

    Query Store is a great performance tuning tool that allows users to store, measure, and fix plan regressions inside an SQL Server database. However, it can store unnecessary information at times, like query information the database administrator might not be interested in. The updated feature allows users to choose the queries they want Query Store to track based on their execution statistics.

    Verbose Truncation Warnings

    T-SQL developers know the pain of getting a truncation error. A user may receive a data truncation error such as “String or binary data would be truncated,” but the exact source of error isn’t specified—like the database name or the truncated values. SQL Server 2019 releases verbose truncation warnings that provide all the details of the data truncation issue.

    Data Virtualization with PolyBase

    PolyBase has been around since 2016, but Microsoft updated it in 2019, giving it the ability to connect to more data sources. It now supports Teradata, Oracle, MongoDB, and other database management systems. PolyBase allows users to join data from a SQL Server instance with external data. They can make data from different sources easily accessible through SQL queries using T-SQL.

    Last Actual Execution Plan DMF

    In SQL Server 2019, there’s a new Dynamic Management Function that allows users to access the last actual execution plan for any query: sys.dm_exec_query_plan_stats. Users can click on the execution column to see details of the execution plan, and in the query, they can see the number of times a particular query was executed.

    What are the alternatives to SQL Server?

    The top alternatives to SQL Server are MySQL, Oracle Database, Amazon Relational Database Service (RDS), SQLite, IBM Db2, Snowflake, and MariaDB.

    Learn about the best relational database software solutions here.