Microsoft SQL Server 2008 R2 Unleashed- P66 pptx

In SQL Server Management Studio, locate the Replication node under the publica-tion server the DBARCH-LT2\SQL08DE01 named instance in this example or the Replication node under the subsc

594 CHAPTER 19 Replication

FIGURE 19.45 Specifying a join filter on the SalesOrderHeader table (limiting the sales

rows that will be published by joining for the North East customers only)

Join filtering allows you to limit the rows you will publish, via join criteria, to another table

Figure 19.45 shows a complex join that filters SalesOrderHeader rows that correspond to

North East Territory customers only (that is, those with TerritoryID values of 1 or 2)

Creating Subscriptions

Now that you have installed and configured the distributor, enabled publishing, and

created a publication, you can create subscriptions

Remember that two types of subscriptions can be created: push or pull Pull subscriptions

allow remote sites to subscribe to any publication that they are allowed to, but for this to

work, you must be confident that the administrators at the other sites have properly

configured the subscriptions at their sites Push subscriptions are easier to create because

all the subscription processes are performed and administered from the

publication/distrib-utor point of view This also makes using them the most common approach

For this example, we use the New Subscription Wizard to create a push subscription:

1 In SQL Server Management Studio, locate the Replication node under the

publica-tion server (the DBARCH-LT2\SQL08DE01 named instance in this example) or the

Replication node under the subscription server (the DBARCH-LT2\SQL08DE03 named

instance in this example) You can create a push subscription from either (but we use

the subscription server here) Open the Replication node, navigate to the Local

Subscription branch, right-click, and choose the New Subscriptions option As you

can see in Figure 19.46, choosing this option launches the New Subscription Wizard,

FIGURE 19.46 Launching the New Subscription Wizard from SQL Server Management Studio

FIGURE 19.47 Identifying the publication from which to subscribe

2 You first need to identify the publisher and publication from which you want to

create one or more subscriptions As you can see in Figure 19.47, we have specified

the publisher (DBARCH-LT2\SQL08DE01) and the publication that has been created for

the AdventureWorks2008 database

596 CHAPTER 19 Replication

FIGURE 19.48 Run all agents at the Distributor (push subscriptions)

3 When you are presented with the option of where the replication agents will be run

for the subscription, choose the first option—having the agents run at the distributor

This makes it a push subscription, which is much easier to control and manage

centrally than a pull subscription (as shown in Figure 19.48)

4 Next, the New Database dialog appears, asking you to identify the database target for

the subscription and the physical database files for its allocation (assuming that you

want to create this from scratch using this wizard process) Figure 19.49 shows this

New Database dialog, with the target database named AdventureWorks2008ODS

Essentially, we have decided to create a subscription that will continuously flow data

from the publisher to the subscriber for all tables in the publication This continuous

replication at the transactional level effectively creates a mirror image of the data for

operational usage That’s why we have used the suffix ODS, for Operational Data

Store, for the new database This is a typical industry usage of replication that takes

all read-only access to OLTP data and offloads it to the ODS copy of the same data

(which is as close to up-to-date as the last transaction that was replicated to it)

5 In the Subscribers screen, with the new entry for the target subscriber server (the

DBARCH-LT2\SQL08DE03 named instance in this example), check the box for the

target subscription server Figure 19.50 shows this subscriber server and the

subscrip-tion database target

6 Specify the process account and connection options for the distribution agent (to

connect to the subscription server) Typically, you choose the option to use a domain

account or choose to impersonate the process account (shown in Figure 19.51)

7 Specify the synchronization schedule for each agent You want the distribution agent

to run continuously, but you also have the options to run on a schedule and on

FIGURE 19.49 The New Database dialog specifying the target database

(AdventureWorks2008ODS)

FIGURE 19.50 Specifying the subscription server target database

598 CHAPTER 19 Replication

FIGURE 19.51 Distribution Agent Security and Synchronization Schedule for the subscription

(Run Continuously)

8 Specify the initialization of the subscription You want the subscription to be

initial-ized immediately, but, depending on the size of the database, this might be

accom-plished manually with a database backup of the publication database

9 On the next screen, which lists the New Subscription Wizard actions, choose to

create the subscription and generate a script file with all the steps to create the

subscription for use later

10 On the next wizard dialog, identify the location of the script to be generated As

shown in Figure 19.52, you are presented with the final wizard summary screen

Click Finish to create your subscription, initialize the subscription database, and

enjoy a full transactional replication implementation

After you click Finish, the create subscription process starts and goes through each

step Remember to check for errors or warnings if any errors occur When this

process completes, you wait for the agents to initialize the target database and start

replication to the subscriber If you have specified that the schema and data be

created immediately, things start happening quickly The distribution agent finishes

the job As you can see in Figure 19.53, the distribution agent applies the schemas to

the subscriber (as viewed from the Replication Monitor’s Distributor to Subscriber

FIGURE 19.52 The New Subscription Wizard summary

FIGURE 19.53 Delivering schemas and data to the subscriber

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FIGURE 19.54 Transactions replicating to the subscriber (pushed)

The complete replication buildup is finished, and you should be fully functional for

repli-cating transactions to the subscriber

Figure 19.54 shows what the replication buildup looks like from the Replication Monitor

as transactions flow through the replication topology This screenshot shows the

transac-tion counts and commands being delivered on the last leg in the journey (from the

distributor to a subscriber) Figure 19.55 shows the full replication topology that was built

(Publisher, Distributor and Subscriber)

Your replication topology is now completely functional and will replicate flawlessly for as

long as you require

Scripting Replication

Earlier, it was strongly suggested that you generate SQL scripts for all that you do because

going through wizards every time you have to configure replication is a difficult way to

run a production environment In the example in the preceding section, you always chose

to generate these scripts as you built up the replication configuration This was only half

the scripts needed, however You must also generate the breakdown scripts (that is, those

that drop and remove replication components) to remove each component of the

replica-tion topology in case you need to start from scratch or, as an example, rebuild a subscriber

that is completely nonfunctional As you can see in Figure 19.56, SQL Server Management

Studio has a great feature that allows the complete generation of all aspects of replication

topology (including disabling and removing replication)

FIGURE 19.55 Full replication topology that was built (Publisher, Distributor, Subscriber)

FIGURE 19.56 A script-generation feature for all replication topology components

NOTE

Remember that working from scripts minimizes the errors you make while supporting

your data replication environments (especially at 3:00 a.m.)

602 CHAPTER 19 Replication

The following example shows the SQL scripts needed to generate the part of the data

repli-cation configuration you just built with the wizard:

From distribution Server

-/****** Scripting replication configuration Script Date: 6/30/2009 10:49:03 AM

******/

/****** Please Note: For security reasons, all password parameters were scripted

with either NULL or an empty string ******/

/****** Begin: Script to be run at Distributor ******/

/****** Installing the server as a Distributor Script Date: 6/30/2009 10:49:03 AM

******/

use master

exec sp_adddistributor @distributor = N’DBARCH-LT2\SQL08DE02’, @password = N’’

GO

Adding the agent profiles

Updating the agent profile defaults

exec sp_MSupdate_agenttype_default @profile_id = 1

GO

exec sp_MSupdate_agenttype_default @profile_id = 2

GO

exec sp_MSupdate_agenttype_default @profile_id = 4

GO

exec sp_MSupdate_agenttype_default @profile_id = 6

GO

exec sp_MSupdate_agenttype_default @profile_id = 11

GO

Adding the distribution databases

use master

exec sp_adddistributiondb @database = N’distribution’, @data_folder = N’C:\

Program Files\Microsoft SQL Server\MSSQL10.SQL08DE02\MSSQL\Data’, @data_file =

N’distribution.MDF’, @data_file_size = 6, @log_folder = N’C:\Program Files\

Microsoft SQL Server\MSSQL10.SQL08DE02\MSSQL\Data’, @log_file =

N’distribution.LDF’, @log_file_size = 3, @min_distretention = 0,

@max_distretention = 72, @history_retention = 48, @security_mode = 1

GO

Adding the distribution publishers

@thirdparty_flag = 0, @publisher_type = N’MSSQLSERVER’

GO

/****** End: Script to be run at Distributor ******/

use master

GO

The complete set of buildup and breakdown scripts for the example used here are available

on this book’s CD They are labeled CreatingXXX.sql for the buildup scripts and

RemoveXXX.sql for the breakdown scripts

Monitoring Replication

After replication is up and running, it is important for you to monitor it and see how

things are running You can do this in several ways, including using SQL statements, SQL

Server Management Studio, and Windows Performance Monitor You are interested in the

agent’s successes and failures, the speed at which replication is done, and the

synchroniza-tion state of tables involved in replicasynchroniza-tion Other issues to watch for are the sizes of the

distribution database, growth of the subscriber databases, and available space on the

distri-bution server’s snapshot working directory

Replication Monitoring SQL Statements

One way to look at the replication configuration and validate row counts, for example, is

to use various replication stored procedures, including the following:

sp_helppublication—Information on the publication server

sp_helparticle—Article definition information

sp_helpdistributor—Distributor information

sp_helpsubscriberinfo—Subscriber server information

sp_helpsubscription—Subscription information

These stored procedures are all extremely useful for verifying exactly how the replication

configuration is really configured If you execute these stored procedures (from the

publi-cation database), you get a great documentation of your complete replipubli-cation topology

that can be included in run books or other system documentation Here’s what you might

do to see how the current replication configuration has been built out:

use AdventureWorks2008

go

exec sp_helppublication

exec sp_helparticle @publication=’PUBLISH AdventureWorks2008 - Transactional’

exec sp_helpdistributor

exec sp_helpsubscriberinfo

exec sp_helpsubscription

go