Module 1:Exploring Replication

Overview

Understanding SQL Server Replication

Setting Up Replication

Understanding Agents in Replication

Securing Replication

Lesson: Understanding SQL Server Replication

Business Problems That Require Replication

The Publisher-Subscriber Metaphor (Articles and Publications; Subscriptions)

Autonomy and Latency

Contrasting Replication with Other Data Distribution Methods

Course Scenario: The Needs of Northwind Traders

Business Problems That Require Replication

Multiple users or locations need copies of the same data

Remote users at distant locations

Mobile disconnected users

Need to improve local performance

Physically separate data based on usage

Improve response time by data aggregation

Distribute database processing across multiple servers

Scale out read-only data

Partition data based on business unit needs

Multimedia: Microsoft SQL Server Replication

This animation reviews the concepts behind SQL Server replication.

Snapshot replication

Transactional replication

Merge replication

The Publisher-Subscriber Metaphor

PublisherPublisherPublisherPublisher

Maintains source databases

Makes data available for replication

DistributorDistributorDistributorDistributor

Receives data changes

Stores metadata, history, and receives and stores changes

May forward changes to Subscribers

Holds copy of data

SubscriberSubscriberSubscriberSubscriber

Publications and Articles

Articles

All tables or parts of tables

Views

Stored procedures

User-defined functions

Publications

One or more articles

Basis of subscription

One or more per database

SubscriptionSubscriptionSubscriptionSubscription

PublicationPublication

Articles

Publication B

Publication A

Subscriptions

Push subscription

Push subscription

Push subscription

Push subscription

Push subscription

Push subscription

Push subscription

Push subscription

Push subscriptionPush subscriptionPush subscriptionPush subscription

Pull subscriptionPull subscriptionPull subscriptionPull subscription

Autonomy and Latency

Snapshot replication

Transactional replication

Updatable snapshot replication

Updatable transactional replication

Lower autonomyLower latency

Lower autonomyLower latency

Higher autonomyHigher latency

Higher autonomyHigher latency

Merge replication

Distributed transactions

Contrasting Replication with Other Data Distribution Methods

MethodMethodMethodMethod

ReplicationReplication

Distributed transactionsDistributed transactions

Distributed queriesDistributed queries

Back up and restoreBack up and restore

AutonomyAutonomyAutonomyAutonomy

VariableVariable

LowLow

LowLow

HighHigh

Data Transformation Services (DTS)Data Transformation Services (DTS) Special use onlySpecial use only

LatencyLatencyLatencyLatency

Variable, depending on typeVariable, depending on type

LowLow

LowLow

HighHigh

Special use onlySpecial use only

Course Scenario: The Needs of Northwind Traders

Distribute their product catalog to regional centers

Mobile disconnected sales force must take orders

Sales information is reported to headquarters

Lesson: Setting Up Replication

Preparing SQL Server for Replication

Locating the Distribution Database

What Is Snapshot Replication?

What Is Transactional Replication?

What Is Merge Replication?

Guidelines for Choosing a Replication Type

Creating Subscriptions by Using SQL Server Enterprise Manager Scripting

Preparing SQL Server for Replication

Limit domain permissions to prevent unauthorized access.

Configure the SQL Server Service account

Need not be run under local or domain administrator account

Configure the SQL Server Agent account

Need not be run under local or domain administrator account

Must have access to each SQL Server involved in replication

Assign additional permissions

Create a file system share on the Distributor

Practice: Create a Shared Folder for Replication Snapshots

Create a shared folder for the replication snapshots

Locating the Distribution Database

locallocalDistributorDistributor

locallocalDistributorDistributor

SubscribersPublisher/Distributor

remoteremoteDistributorDistributor

remoteremoteDistributorDistributor

SubscribersDistributorPublisher

Practice: Locating the Distribution Database

Select and register a replication partner

Install replication, locating the replication database

What Is Snapshot Replication?

Distributes data as it appears at a moment in time

Does not monitor for updates to the data

Takes longer to propagate data modifications

A point in time snapshot image

What Is Transactional Replication?

Permits immediate replication of data modifications

Uses the following steps:

Initial snapshot propagation

Data modified at Publisher

Individual transactions captured

Transactions propagated to Subscribers

What Is Merge Replication?

Allows sites to work autonomously

Merges the updates between sites when they are connected

Guidelines for Choosing a Replication Type

Snapshot replication

Data does not change often New data need not be immediately distributed

Transactional replication

Data modifications propagated in seconds Transactions applied completely or not at all

Merge replication

Multiple Subscribers need to update at various times Site autonomy is critical

Creating Subscriptions By Using SQL Server Enterprise Manager Scripting

Replication supports Transact-SQL scripting

Use SQL Server Enterprise Manager scripting menus

Lesson: Understanding Agents in Replication

Replication Agents

SQL Server Agent

Scheduling Replication with SQL Server Agent

Agent Profiles

Replication Agents

SnapshotSnapshotSnapshotSnapshot

Snapshot AgentSnapshot Agent

Distribution AgentDistribution Agent

TransactionalTransactionalTransactionalTransactional

Snapshot AgentSnapshot Agent

Distribution AgentDistribution Agent

Log Reader AgentLog Reader Agent

Queue Reader AgentQueue Reader Agent

MergeMergeMergeMerge

Snapshot AgentSnapshot Agent

Merge AgentMerge Agent

SQL Server Agent

Starting Agents

Scheduled jobs

Command line

ActiveX controls

sqlinitx.dll

sqldistx.dll

sqlmergx.dll

Scheduling Replication with SQL Server Agent

Continuous Least latency Suitable for well-connected

Subscribers with available network bandwidth

Scheduled Any frequency Suitable for synchronizing

data during off-peak hours

On-demand Administrator or application

explicitly invokes Suitable for mobile

disconnected users

Agent Profiles

Lesson: Securing Replication

The Role of Agents in Securing Replication

Troubleshooting Security Context Issues

Securing Replication By Using SQL Server Roles

Gaining Access to a Publication

Securing the distributor_admin Login

The Role of Agents in Securing Replication

SQL Server Agent account provides the security context for running jobs

Replication is a series of jobs

Initial security context is job owner account

Job runs under SQL Server Agent account

Managing validation failure

SQL Server Service security context

User-based security for Windows 9x

Troubleshooting Security Context Issues

Finding information about security context issues

SQL Server Agent error log Windows event log

Recognizing security context issues

Replication Agent does not start Error 8198

Resolving security context issues

Change the owner of the replication job Use another login

Securing Replication by Using SQL Server Roles

sysadmin can: Enable, modify, or drop a Distributor, Publisher, or Subscriber Enable a database for replication Configure an agent profile Monitor a replication agent

sysadmin or db_owner can: Create, drop, modify, or grant access to a publication Create, or delete a subscription Enable snapshots for File Transfer Protocol downloading using the

Internet. Initiate cleanup of the distribution database Schedule jobs (db_owner of the msdb database)

Gaining Access to a Publication

Securing the distributor_admin Login

Distributor_admin is a special-purpose login

Set a password for the distributor_admin account

Change password with:

sp_changedistributor_password

Distributor tab of the Publisher and Distributor Properties in SQL Server Enterprise Manager

Review

Understanding SQL Server Replication

Setting Up Replication

Understanding Agents in Replication

Securing Replication