Instructor InputsSession 9..Session OverviewThis session includes the following topics: Linked pps

This session includes the following topics: Linked servers Types of replication Monitoring and improving replication performance Resolving conflicts in merge replication Recove

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Instructor Inputs S e

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This session includes the following topics:

Linked servers

Types of replication

Monitoring and improving replication performance

Resolving conflicts in merge replication

Recovering from a failure in replication

Best practices

Tips and Tricks

Slide 1

Installing Windows XP Professional Using Attended Installation Querying, Managing, and Administering Databases Using SQL Server 2005 Objectives

In this session, you will learn about:

Linked servers Types of replication Monitoring and improving replication performance Resolving conflicts in merge replication Recovering from a failure in replication Using KILL statement

Best practices that can be considered while replicating databases in SQL Server 2005

Tips and tricks that will help you use import and export utilities

in SQL Server 2005 FAQs related to replication concepts of SQL Server 2005

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Slide 2 of 19 Ver 1.0 Collaborate Session 9

Knowledge Byte

Linked server:

Is like an alias on a local SQL Server that points to an external data source

Offers the following advantages:

Remote server access.

The ability to issue distributed queries, updates, commands, and transactions on heterogeneous data sources across the enterprise.

The ability to address diverse data sources similarly.

Specifies the following objects:

An OLE DB provider

An OLE DB data source

Slide 3

Installing Windows XP Professional Using Attended Installation Querying, Managing, and Administering Databases Using SQL Server 2005 Knowledge Byte (Contd.)

SQL Server 2005 provides the following types of replications:

Snapshot replication:

is used to replicate data that does not change frequently

is also used when the subscribers require read-only data with a high degree of latency time

Transactional replication:

is used when the subscribers require the updated data with minimal delay

is generally implemented at the server-to-server level.

Merge replication:

is used when both the publishers as well as the subscribers can change the data In this case, changes are replicated to all the subscribers and publishers until all the servers have the same data.

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Knowledge Byte (Contd.)

Replication Monitor:

Is a graphical tool that allows you to track the overall activity of

a replication

Provides information on the status and performance of publications and subscriptions

Window has two panes, the left and the right pane

The left pane shows the list of publishers and its associated publications

The right pane contains three tabs, All Subscriptions, Tracer Tokens, and Warnings and Agents.

Slide 5

Replication conflict occurs in merge replication when copies

of an article that are part of a subscription are updated at two subscriber locations or on a publisher and a subscriber.

The articles can be updated by any of the INSERT, UPDATE, or DELETE DML statements The detection of replication conflict is done by the merge agent.

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Knowledge Byte (Contd.)

To recover from a failure in replication:

A best practice is to maintain back ups of the publisher and subscriber data

Take a full backup of the publisher database and maintain regular backups at regular intervals after short periods

Maintain backup of distribution database

Set the minimum transaction retention period at the distributor.

This retention period should be greater than the transaction log backup period at publisher

Slide 7

The KILL statement is used to terminate a process on the basis of the session ID

The KILL statement can also be used to terminate a normal connection, which internally terminates the transactions that are associated with the specified session ID

The syntax of using a KILL statement is:

KILL { session ID } [ WITH STATUSONLY ]

where,

session_ID is the session ID of the process to terminate.

session_ID is a unique integer that is assigned to each user connection when the connection is made.

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Best Practices

Program your application to use stand by server in case of database failover.

Backup replication databases regularly.

The following databases should be backed up regularly:

Publication database Distribution database Subscription databases msdb database and master database at the Publisher, Distributor, and Subscribers server

Validate data periodically to verify the replication between Subscriber and Publisher.

Slide 9

Installing Windows XP Professional Using Attended Installation Querying, Managing, and Administering Databases Using SQL Server 2005 Tips and Tricks

When the bcp utility is connecting to SQL Server with a trusted connection using integrated security, use the -T option (trusted connection) instead of the user name and password combination.

While using bcp utility do not use a blank password, use a strong password.

While using bcp utility, if the file name includes a space or quotation mark at the command prompt, enclose the identifier in quotation marks ("").

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Do you need to stop an Activity on a database when it is published?

No, Activity can continue on a database while a publication is being created.

FAQs

Slide 11

Installing Windows XP Professional Using Attended Installation Querying, Managing, and Administering Databases Using SQL Server 2005

When is a subscription available?

A subscription is available after a snapshot has been applied

to the subscription database.

FAQs (Contd.)

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What recovery model is required on a replicated database?

Replication functions properly using any of the recovery models: simple, bulk-logged, or full.

FAQs (Contd.)

Slide 13

Installing Windows XP Professional Using Attended Installation Querying, Managing, and Administering Databases Using SQL Server 2005

Does replication encrypt data?

No, replication does not encrypt data that is stored in the database or transferred over the network.

FAQs (Contd.)

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Does replication resume if a connection is dropped?

Yes, replication processing resumes at the point at which it left off if a connection is dropped.

FAQs (Contd.)

Slide 15

Installing Windows XP Professional Using Attended Installation Querying, Managing, and Administering Databases Using SQL Server 2005 Challenge

Which of the following editions of SQL Server 2005 allows database snapshots?

Standard edition Enterprise edition Express edition Workgroup edition

Answer:

Enterprise edition

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Challenge (Contd.)

You want to create a database snapshot Which command will you use with AS SNAPSHOT OF clause to create a snapshot of a database?

CREATE SNAPSHOT ALTER DATABASE ALTER SNAPSHOT CREATE DATABASE

Answer:

CREATE DATABASE

Slide 17

Installing Windows XP Professional Using Attended Installation Querying, Managing, and Administering Databases Using SQL Server 2005 Challenge (Contd.)

Which of the following task you cannot perform with respect

to database snapshots?

Create multiple snapshots of a database Drop files from database snapshot Create table through a snapshot Create snapshot on the same server instance as the source database

Answer:

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Challenge (Contd.)

Which of the following command reverts back a database from a snapshot?

RETRIEVE DATABASE <db1> FROM DATABASE_SNAPSHOT=<Sn1>

RESTORE DATABASE FROM DATABASE_SNAPSHOT=<Sn1>

RESTORE DATABASE <db1> FROM DATABASE_SNAPSHOT=<Sn1>

RETRIEVE DATABASE FROM DATABASE_SNAPSHOT=<Sn1>

Answer:

RESTORE DATABASE <db1> FROM DATABASE_SNAPSHOT=<Sn1>

Slide 19

Installing Windows XP Professional Using Attended Installation Querying, Managing, and Administering Databases Using SQL Server 2005 Challenge (Contd.)

Which of the following method is used to query against a linked server?

openlink() openquery() createquery() createlink()

Answer:

openquery()

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1 b Enterprise edition

3 b Drop files from a database snapshot

4 c RESTORE DATABASE <db1> FROM DATABASE_SNAPSHOT=<Sn1>

5 b openquery() method

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1 Which of the following is the publisher in replication implementation by using SQL Server 2005?

a Database server that replicates the data and database objects

b Database objects that are to be replicated

c Database data that is replicated

d Database server that takes the publication

2 Which of the following creates the snapshot of data in the primary server?

a Replication job

b Database server

c Distributor

d Replication agent

3 Which replication agent transfers the changes made to the publication from the distributor to the subscribers?

a Snapshot agent

b Distributor agent

c Log reader agent

4 Which replication job detects replication agents that are not actively logging history?

a Agent history clean up

b Distribution clean up

c Expired subscription clean up

d Replication agent checkup

5 Which type of replication is used to replicate data that does not change frequently?

a Merge replication

b Transaction replication

c Snapshot replication

d Distribution replication

6 Consider the following stages of a replication process:

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independently?

a Transactional publication

b Snapshot publication

c Merge publication

d Transactional publication with updatable subscriptions

8 What is the default value for the replication latency threshold?

9 Which statement is not true with regard to the BCP utility?

a It is a command line utility

b It is used to copy the SQL Server data to or from an operating system data file

c It provides the BCP GET and BCP SET operations

d BCP parameters are case-sensitive

10 Which of the following tool/command is not used to import and export data in SQL

Server 2005?

b BCP Utility

d Bulk Import Tool

Solutions

1 Database server that replicates the data and database objects

2 Replication agent

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Replication refers to a set of technologies used for copying and distributing data and database objects from one database to another and then synchronizing the databases to maintain consistency

Discuss the need for replicating data in an enterprise In addition, discuss the different replication types and their respective uses

Instructor Inputs

You can conduct the discussion as follows:

Encourage the students to discuss the need for replication in an enterprise

Ask the students to discuss the different replication types with the help of different situations in which each replication type is useful

Solution

Replicating data at physically different locations helps in quick access of data In addition,

it reduces network traffic, as the users do not need to send the data to a distant server for every transaction Replication involves various components such as publisher, distributor, and subscriber Synchronization of data between these components depends on the type of replication you select, such as snapshot replication, transactional replication, or merge replication

Snapshot Replication

Snapshot replication is used to replicate data that does not change frequently It is also used when the subscribers require read-only data with a high degree of latency time For example, the price list of a sales organization changes once or twice a year In this case, you can replicate the snapshot of the data after it has changed

Transactional Replication

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the data In this case, changes are replicated to all the subscribers and publishers until all

the servers have the same data Consider an example of a book store, which has various

regional offices Every office has its own database server The transaction details at the

regional offices need to be synchronized In such a case, merge replication can be

implemented

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