History of Microsoft SQL Server

About the time Windows NT was released in July 1993, Sybase and Microsoft parted ways and each pursued its own design and marketing schemes.

Until 1994, Microsoft's SQL Server carried three Sybase copyright notices as an indication of its origin.

User Mode Scheduling (UMS) was introduced to handle SQL Server threads better than Windows preemptive multi-threading, also adding support for fibers (lightweight threads, introduced in NT 4.0, which are used to avoid context switching[2]).

Although there were pre-release versions of SQL 2000 (as well as Windows 2000) compiled for Alpha, these were canceled and were never commercially released.

These include: SQL Server 2000 also introduced many T-SQL language enhancements, such as table variables, user-defined functions, indexed views, INSTEAD OF triggers, cascading referential constraints and some basic XML support.

For relational data, T-SQL has been augmented with error handling features (try/catch) and support for recursive queries with CTEs (Common Table Expressions).

Data pages are checksummed for better error resiliency, and optimistic concurrency support has been added for better performance.

SQL Server 2008 (formerly codenamed "Katmai")[14][15] was released on August 6, 2008, announced to the SQL Server Special Interest Group at the ESRI 2008 User's Conference on August 6, 2008, by Ed Katibah (Spatial Program Manager at Microsoft), and aims to make data management self-tuning, self organizing, and self maintaining with the development of SQL Server Always On technologies, to provide near-zero downtime.

In current versions, such multimedia data can be stored as BLOBs (binary large objects), but they are generic bitstreams.

[19] SQL Server 2008 also natively supports hierarchical data, and includes T-SQL constructs to directly deal with them, without using recursive queries.

Approximately 70 methods are available to represent spatial operations for the Open Geospatial Consortium Simple Features for SQL, Version 1.1.

[28] Volume licensed Standard, Web, Enterprise, Workgroup and Datacenter editions of SQL Server 2008 are eligible for the Extended Security Updates program.

[30][31] Those volume licensed editions rehosted on Microsoft Azure automatically received ESUs until July 11, 2023.

[32][33][34][35] SQL Server 2008 R2 (10.50.1600.1, formerly codenamed "Kilimanjaro") was announced at TechEd 2009, and was released to manufacturing on April 21, 2010.

[44] Volume licensed Standard, Enterprise, Datacenter and Embedded editions of SQL Server 2008 R2 are eligible for the Extended Security Updates program.

[46] SQL Server 2012's new features and enhancements include Always On SQL Server Failover Cluster Instances and Availability Groups which provides a set of options to improve database availability,[47] Contained Databases which simplify the moving of databases between instances, new and modified Dynamic Management Views and Functions,[48] programmability enhancements including new spatial features,[49] metadata discovery, sequence objects and the THROW statement,[50] performance enhancements such as ColumnStore Indexes as well as improvements to OnLine and partition level operations and security enhancements including provisioning during setup, new permissions, improved role management, and default schema assignment for groups.

[53][32] All volume licensed editions of SQL Server 2012 are eligible for the Extended Security Updates program.

[33][31] Those volume licensed editions rehosted on Microsoft Azure automatically receive ESUs until July 8, 2025.

[55] SQL Server 2014 provides a new in-memory capability for tables that can fit entirely in memory (also known as Hekaton).

[56] For disk-based SQL Server applications, it also provides the SSD Buffer Pool Extension, which can improve performance by cache between RAM and spinning media.

SQL Server 2014 also enhances the Always On (HADR) solution by increasing the readable secondaries count and sustaining read operations upon secondary-primary disconnections, and it provides new hybrid disaster recovery and backup solutions with Microsoft Azure, enabling customers to use existing skills with the on-premises version of SQL Server to take advantage of Microsoft's global datacenters.

[61] All volume licensed editions of SQL Server 2014 are eligible for the Extended Security Updates program.

[31] Those volume licensed editions rehosted on Microsoft Azure automatically receive ESUs until July 12, 2027.