module 11: introducing replication. overview introduction to distributed data introduction to sql...

Module 11: Introducing Replication

Overview

Introduction to Distributed Data

Introduction to SQL Server Replication

SQL Server Replication Agents

SQL Server Replication Types

Physical Replication Models


The Need for Distributed Data

Considerations for Distributing Data

Methods to Distribute Data

The Need for Distributed Data

Brings Data Closer to the User

Allows Site Independence

Separates

Online transaction processing

Read-intensive applications

Can Reduce Conflicts

Considerations for Distributing Data

Factors

Timing/Latency

Site Autonomy

Transactional Consistency

ReplicationReplicationReplicationReplication

UPDATE

Distributed TransactionsDistributed TransactionsDistributed TransactionsDistributed Transactions

UPDATE UPDATE

Methods to Distribute Data

Snapshot Replication

Transactional Replication

Snapshot Replication with Immediate or Queued Updating Subscriptions

Transactional Replication with Immediate or Queued

Updating Subscriptions

Distributed Transactions

Lower AutonomyLower Latency

Lower AutonomyLower Latency

Higher AutonomyHigher Latency

Higher AutonomyHigher Latency

Merge Replication


The Publisher-Subscriber Metaphor

Publications and Articles

Filtering Data

Subscriptions

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

Publication The basis of a subscription A collection of one or more articles Can have one or more publications per database

Article

Data from a whole or filtered partition of a table or a database object

Part of a publication

Filtering Data

Subscriber

Vertical Filtering

Horizontal Filtering

234567

1A B C D E F

234567

1A B C D E F

234567

1A B E

36

2A B C D E F

Table A

Table B Publisher

Subscriptions

Subscriber 3Subscriber 3Subscriber 3Subscriber 3

Push Subscription

Push Subscription

Push Subscription

Push SubscriptionPublication BPublication BPublication BPublication B

Subscriber 2Subscriber 2Subscriber 2Subscriber 2

Push Subscription

Push Subscription

Push Subscription

Push SubscriptionSubscriber 1Subscriber 1Subscriber 1Subscriber 1

Push SubscriptionPush SubscriptionPush SubscriptionPush Subscription

Publication APublication APublication APublication A

Pull SubscriptionPull SubscriptionPull SubscriptionPull Subscription


Snapshot Agent

Prepares initial snapshots and stores them on the distributor Distribution Agent

Moves snapshot and transactional data to Subscribers Log Reader Agent

Copies data from transaction log to the distribution database Merge Agent

Merges changes from multiple sites Queue Reader Agent

Applies changes from a queue and applies them to multiple subscribers


Overview of the Replication Types

Considerations for Using Merge Replication

Overview of the Replication Types

Snapshot Replication

Periodic bulk transfer of new snapshots of data

Transactional Replication

Replication of incremental changes

Merge Replication

Autonomous changes to replicated data are later merged

Considerations for Using Merge Replication

Changes to the Schema

Identifies a unique column Adds several system tables Creates triggers at Publisher and Subscriber

Conflict Resolution

Tracks updates Compares values and resolves conflicts Replicates only synchronized data


Overview of the Physical Replication Models

Combining Physical Replication Models and Types

Central Publisher/Remote Distributor Example

Central Subscriber/Multiple Publishers Example

Multiple Publishers/Multiple Subscribers Example

Overview of the Physical Replication Models

Central Subscriber/Multiple PublishersCentral Subscriber/Multiple PublishersCentral Subscriber/Multiple PublishersCentral Subscriber/Multiple Publishers

Publisher/Distributor

SubscriberPublisher/Distributor



Multiple Publishers/Multiple SubscribersMultiple Publishers/Multiple SubscribersMultiple Publishers/Multiple SubscribersMultiple Publishers/Multiple Subscribers

Publisher/Distributor/Subscriber



Subscribers


Central Publisher/DistributorCentral Publisher/DistributorCentral Publisher/DistributorCentral Publisher/Distributor

Combining Physical Replication Models and Types

The Model Is the Physical Implementation

The Type Provides the Functionality

Any of the Models Can Use Any of the Types

Central Publisher/Remote Distributor Example

New York

Publisher

London

Subscribers

Rome

Paris

Dublin

RemoteDistributor

Central Subscriber/Multiple Publishers Example

RRegion1 Ordersegion1 OrdersRRegion1 Ordersegion1 OrdersPrimary KeyPrimary Key

Reg_codeReg_code IdId Order_noOrder_no

1 1

1 1

10003100

10003100

~~

~~

QtyQty

1522

1522

RRegion2egion2 Orders OrdersRRegion2egion2 Orders OrdersPrimary KeyPrimary Key


2 2

2 2

10002380

10002380

~~

~~

QtyQty

328

328

RRegion4 Ordersegion4 OrdersRRegion4 Ordersegion4 OrdersPrimary KeyPrimary Key


4 4

4 4

10002000

10002000

~~

~~

QtyQty

4330

4330

RRegion3 egion3 OrdersOrdersRRegion3 egion3 OrdersOrdersPrimary KeyPrimary Key


3 3

3 3

10001070

10001070

~~

~~

QtyQty

719

719

Publisher

Publisher

Publisher

Publisher Subscriber

MasterMaster O OrdersrdersMasterMaster O OrdersrdersPrimary KeyPrimary Key


1 1 2 2 3 3 4 4

1 1 2 2 3 3 4 4

10003100100023801000107010002000

10003100100023801000107010002000

~~~~~~~~

~~~~~~~~

QtyQty

1 1 2 2 3 3 4 4

1 1 2 2 3 3 4 4

11

10003100

~~

1522

22

10002380

~~

328

33

10001070

~~

719

44

10002000

~~

4330

Multiple Publishers/Multiple Subscribers Example

OOrders rders (Shop A)(Shop A)OOrders rders (Shop A)(Shop A)Primary KeyPrimary Key

AreaArea IdId Order_noOrder_no

1 12233

1 12233

100031001000238010001070

100031001000238010001070

~~~~~~

~~~~~~

QtyQty

15223287

19

15223287

19

11

10003100

~~

1522

OOrders rders (Shop B)(Shop B)OOrders rders (Shop B)(Shop B)Primary KeyPrimary Key


112233

112233

100031001000238010001070

100031001000238010001070

~~~~~~

~~~~~~

QtyQty

15223287

19

15223287

19

22

10002380

~~

328

OOrders rders (Shop C)(Shop C)OOrders rders (Shop C)(Shop C)Primary KeyPrimary Key


112233

112233

100031001000238010001070

100031001000238010001070

~~~~~~

~~~~~~

QtyQty

15223287

19

15223287

19

33

33

10001070

10001070

~~

~~

719

719

Publisher/Subscriber

Publisher/SubscriberPublisher/Subscriber

Recommended Practices

Determine the Acceptable Degree of Data LatencyDetermine the Acceptable Degree of Data Latency

Select an Appropriate Replication TypeSelect an Appropriate Replication Type

Select the Physical Replication ModelSelect the Physical Replication Model

Determine Whether to Allow Updates to Replicated DataDetermine Whether to Allow Updates to Replicated Data

Lab A: Implementing Replication

Review






module 11: introducing replication. overview introduction to distributed data introduction to sql...

Documents

replication reviewintroduction

distributed dataconsiderations

transactional data

datathe need

merge replicationoverview

merge replicationchanges

transaction log

typesthe model