This document summarizes key differences between front-end applications like Access and the SQL Server backend. It also provides overviews of SQL Server transactions, server architecture including protocols and components, how select and update requests are processed, and uses of dynamic management views.

1. SQL ServerManagement2008Sandra Shinsandyshin@msn.com

2. 1SQL Server vsFront End Applications

3. Front End (Client) Server SideAccessSQL ServerPowerful RDBMS

4. Features Interactive Forms to display and manipulate dataSupports ODBC connectivity

5. Has basic security features

6. Does not provide transactional functionality

7. Very basic backup functionality

8. Does not support multi-user operation

9. Works with 1 database at a time

10. Extremely powerful RDBMS

11. No client-usable Forms

12. Supports ODBC connectivity

13. Has robust, layered security features

14. Provides transactional functionality

15. Comprehensive backup functionality

16. Supports multi-user operation

17. Oversees multiple databases at a time2TransactionA unit of work containing several commands to access, manipulate, store and extract data from a database..

18. Transaction ACID RequirementsAAtomicity- The transaction must complete all of the commands in their entirety or none of them.CConsistency- The transaction cannot break the integrity rules of the databaseIIsolation- The transaction must be entirely self-contained, changes it makes must not be readable by any other transactionDDurability- The results of a committed transaction must persist even if there's a system failure

19. Types of TransactionsImplicit – an action code block which runs completely when executed (SQL default) – cannot be rolled backensuring atomicityExplicit– code within a transaction block which contains code to CONTROL rollback and COMMITBEGIN TRANSACTIONT SQL commandsInsert SAVEPOINT, if needed, to mark a rollback stop pointEitherCOMMIT TRANSACTION or ROLLBACK TRANSACTIONAtomicity is ensured by the requirement that all commands withingth code block be completed before thr changes are committed

20. 3Server Architecture

22. SNIis a protocol layer that establishes network connection between the client and the server containing a set of APIs that are used by both the database engine and the SQL Server Native Client (SNAC) .SQL Server supports the following protocolsShared memory - the default protocol is to connect from a client running on the same computer as SQL Server. TCP/IP- the most common access protocol enables connection using an IP address and port number Named pipes - were developed for local area networks and can be inefficient across slower networks such WANsVIA - Virtual Interface Adapter enables high-performance communication between two systems require specialized hardware at both ends and a dedicated connectionSQL Server network interface (SNI)

23. Protocol Layers Establish Connection Regardless of the protocol. Once a connection is established , SNI creates a secure connection to a Tabular Data Stream (TDS) end point on the server which is used to send requests and receive data.

24. There is one TDS endpoint for each protocol and one reserved for the use by the Dedicated Administrator Connection (DAC)Select Request - Protocol LayerThe SQL Server ‘s protocol layer Receives a TDS packet

25. Unwraps the package Reversing the SNI’s client packet preparation process)

26. Determines the request contents. When the requested READ is complete,Packages the results and status messages to send back to the client as TDS messagesTDS

27. SQL Server ComponentsRelational Engine (Query Processor) Primary function: to optimize queries and execution. Command ParserChecks query syntax and prepares query tree

28. Query Optimizer Determines the execution plan

29. Query Executor Runs the codeSQL Server ComponentsStorage engine Responsible for managing all I/O to the dataAccess MethodHandles I/O requests for rows, indexes, pages, allocations and row versionsBuffer Manager Deals with SQL’s main memory consumer, the Buffer PoolTransaction ManagerHandles locking of data to ensure ACID properties and manages the transactions law