T-SQL Tuesday #10 – Applying Indexes To Replicated Tables

SQL Server Best Practices
SQL Server Best Practices
It’s T-SQL Tuesday time again! This month Michael J. Swart (blog|twitter) is hosting and has given us the topic of indexes.

I’ve previously written about how you can find indexes that are not being used and get their sizes. Not being allowed to reuse that meant that I had to come up with something else.

 In my previous post on calculating replication schema options I documented a way of being able to change article options in transactional replication so that you could apply all the non-clustered indexes on your subscribing table that exist on the publishing one. But what if you are using replication to offload reporting and you need to create indexes that don’t exist on the publishing table?

You could always manually apply these indexes any time that you perform a snapshot but this requires manual work and can easily be forgotten.

Fortunately there is another option, you can have replication automatically apply a post-snapshot SQL script which will create those indexes for you. Here’s how…

Create a basic publication (snapshot or transactional) and add a table article. Perform the snapshot and compare indexes between the tables (in this example I am using the person.address table from AdventureWorks2008).

After the snapshot here’s how the indexes stand

For this example we’re going to create a new index on Admindb.person.address. To do this first we need to generate the index creation script

USE AdminDB
GO

IF NOT EXISTS (SELECT * FROM sys.indexes WHERE object_id = OBJECT_ID(N‘[person].[address]’) AND name = N’NCIX_Zip’)
CREATE NONCLUSTERED INDEX [NCIX_Zip] ON [person].[address]
(
    [PostalCode] ASC
)
WITH (ONLINE = ON, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
GO

Save this script to C:\ReplicationScripts\CreateReportingIndex.sql

Now we change the existing publication so that whenever a snapshot is taken it will apply this script when applied to the subscriber. This change can be done in a couple of ways.

Continue reading on SirSQL.net.

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