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SQL Server 2005 The Common Language Runtime (CLR) Integration

SQL Server 2005 The Common Language Runtime (CLR) Integration. CLR Integration CLR Introduction. Highlights Common type system (CTS) Mapping of data types. Programming language  Framework Just-in-time (JIT) compilers JIT compiles intermediary language (MSIL) into native code

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SQL Server 2005 The Common Language Runtime (CLR) Integration

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  1. SQL Server 2005The Common Language Runtime (CLR) Integration

  2. CLR IntegrationCLR Introduction • Highlights • Common type system (CTS) • Mapping of data types. Programming language  Framework • Just-in-time (JIT) compilers • JIT compiles intermediary language (MSIL) into native code • Highly optimized for platform or device • Garbage collector • Permission and policy-based security • Exceptions • Threading • Diagnostics and profiling

  3. Thread Support COM Marshaler Type Checker Exception Manager Security Engine Debug Engine MSIL to Native Compilers (JIT) Code Manager Garbage Collector (GC) CLR IntegrationCLR Diagram • Common Language Runtime Diagram Base Class Library Support Class Loader

  4. CLR IntegrationSQL Server 2005 – CLR • Run managed code within a database by using in-process assemblies • Create managed stored procedures, triggers, user-defined functions, user-defined types, and aggregates • Integration benefits: • Enhanced programming model • Enhanced safety and security • Common development environment • Performance and scalability

  5. SQL Engine CLR Hosting Layer SQL OS Layer Windows OS CLR IntegrationDeep Integration with the Database • CLR Hosting layer provides coordination • Assembly Loading • Memory management • Security Model • Reliability • Threads & Fibers • Deadlock detection • Execution context

  6. Build VB,C#,C++ Assembly: “TaxLib.dll” SQL Data Definition: create assembly … create function … create procedure … create trigger … create type … SQL Queries: select sum(tax(sal,state)) from Emp where county = ‘King’ SQL Server The Developer Experience VS .NET Project Runtime hosted by SQL (in-proc)

  7. CLR IntegrationAvailable Classes • Even in supported assemblies, some APIs are not available in SQL • Environment.Exit(), Console, etc. • Potentially unreliable constructs disabled • No thread creation • No shared state or synchronization • No listening on sockets in server • No finalizers • Eliminate functionality N/A to database • System.Windows.Forms • System.Drawing • System.Web, …

  8. CLR IntegrationSQL Server Projects in Visual Studio 2005 • Project for creating managed database objects • Automatically includes necessary references • System • System.Data.dll • Includes templates for each object type • Stored procedure • Trigger • User-defined function • User-defined type • Aggregate • Allows immediate deployment and debugging

  9. CLR IntegrationThe System.Data.SqlServer Namespace

  10. CLR IntegrationRegistering an assembly • CREATE ASSEMBLY assembly_name • [ AUTHORIZATION owner_name ] • FROM { < client_assembly_specifier > | < assembly_bits > [,...n] } • [ WITH PERMISSION_SET = { SAFE | EXTERNAL_ACCESS | UNSAFE } ] • < client_assembly_specifier > :: = • '[\\machine_name\]share_name\[path\]manifest_file_name' • < assembly_bits > :: = • { varbinary_literal | varbinary_expression }

  11. CLR IntegrationAssembly Security -PERMISSION_SET • SAFE • May not access external resources: registry, file system, or network • May access data using the current context but not via SQLClient or any other data provider • No thread processing • EXTERNAL_ACCESS • May access external resources:registry, file system, network, environment variables • UNSAFE • May access external resources • Can use SQLClient and other data providers • Can use thread constructs • (No restrictions; similar to extended stored procedures)

  12. CLR IntegrationMeta Data of Assemblies Create Assembly Assembly source code: Sys.assembly_files Assembly references: Sys.assembly_references Details of Assembly: Sys.assemblies Other meta data information • SYS.OBJECTS • SYS.ASSEMBLY_MODULES • SYS.ASSEMBLY_TYPES

  13. CLR IntegrationUser Defined Functions • Similar to T-SQL function • Written in CLR language • Decorated with [SqlFunction] attribute in code • Assembly loaded into the database • Function defined from assembly • Limits on functions • must be in public class • cannot be in nested class • method must be public and static

  14. CLR IntegrationUser Defined Functions -Example public class MyFunctions { [SqlFunction] public static SqlString GetLongDate(SqlDateTime DateVal) { // Return the date as a long string return DateVal.Value.ToLongDateString(); } }

  15. CLR IntegrationUser Defined Functions • Properties have impact on whether or not computed column that use these functions can be indexed. • IsDeterministic = true (it always produces the same output values given the same input values and the same database state.) • DataAccess • DataAccessKind.None: Does not access data. • DataAccessKind.Read: Only reads data. • SystemDataAccess • SystemDataAccessKind.None: Does not access system data. • SystemDataAccessKind.Read: Only reads system data. • IsPrecise = { true | false } (that indicates whether the routine involves imprecise computations such as floating point operations. )

  16. CLR Integration.Net Stored Procedures (1) • Capable of doing everything a T-SQL proc can do. • Uses a Shared method (static in C#) • Pass parameters both ways • OUTPUT parameters should be byref (ref in C#) • Return multiple result sets

  17. CLR Integration.Net Stored Proc Can Return (2) • Numeric return code • Count of rows affected by the command • Scalar value • Single row • One or more multi row result sets • A stream of XML

  18. CLR IntegrationStored Procedure public class ContactCode { [SqlProcedure] public static void GetContactNames() { SqlCommand cmd = ……. …… cmd.CommandText = "SELECT FirstName + ' ' + LastName" + • " AS [Name] FROM Person.Contact"; SqlDataReader rdr = cmd.ExecuteReader(); SqlPipe sp = …………..; sp.Send(rdr); } }

  19. CLR IntegrationCreate Sql Server Proc. Syntax : create procedure ProcName as external name <assemblyname>.<classname>.<methodname> Example : create procedure GetContactsName as external name assemblyname.ContactCode. GetContactNames

  20. CLR IntegrationTriggers public class ContactCode { [SqlTrigger(Name="ContactUpdTrg", Target="Person.Contact", Event="FOR UPDATE")] public static void ChangeEmail() {SqlTriggerContext trg = SqlContext.GetTriggerContext();

  21. CLR IntegrationWhen to use T-SQL • T-SQL better used for data access • All pre-SQL Server 2005 code is written in T-SQL • SQL Server 2005 adds exception handling to T-SQL • T-SQL can be faster for data access • Direct access to SQL Server's internal buffers • Rich, data-centric library of functions • No conversion of types

  22. CLR IntegrationFeature Comparison with T-SQL

  23. CLR IntegrationBest uses of SQLCLR • Computational functions are always faster • Streaming table valued functions • User defined aggregates • Orders magnitude faster than server or client cursor solutions • Scalar functions • Function body is compiled to native code • Use managed code for: • Procedures that feature complex logic • Access to the .NET Framework class library • CPU intensive functions

  24. SQLCLR GuidanceMid Tier vs. Data Tier • SQLCLR support does not mean move all business logic to server • Candidates for moving to server • Centralized data validation • Process large amount of data while needing a small portion of it for application use

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