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SQL Server replication is a versatile feature that allows you to copy and distribute data from one database to another and then synchronizes them to maintain consistency. It allows you to maintain multiple copies of data at different locations, therefore enhancing the performance and availability of applications.
Setup
To set up replication, you need to work with a publisher, distributor, and subscriber model. The publisher is the database that owns the data, distributor is the database that hosts the distribution database and helps manage the data flow, while the subscriber is the database that receives the replicated data.
Types of Replication
There are three types of replication we can use – Transactional, Merge and Snapshot. The Transactional replication type is typically used when we want incremental changes to be propagated to subscribers. Merge replication, as the name suggests, is used when we need data from multiple sources to be combined into a single centralized database. The Snapshot replication is used when we want an exact copy of the publisher’s data at subscriber’s end.
Transactional Replication in SQL Server: Code Example
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-- Step 1: Configure the distribution. EXEC s<a href="mailto:p_replicationdboption @dbname" >p_replicationdboption @dbname</a> = N'myDatabase', @optname = N'publish', @value = N'true'; -- Step 2: Create a publication. EXEC s<a href="mailto:p_addpublication @publication" >p_addpublication @publication</a> = N'myPublication', @description = N'Transactional publication of database from publisher.', @sync_method = N'concurrent'; -- Step 3: Add a table article for employees to the publication. EXEC s<a href="mailto:p_addarticle @publication" >p_addarticle @publication</a> = N'myPublication', @article = N'employees', @source_owner = N'dbo', @source_object = N'employees'; |
Merge Replication in SQL Server: Code Example
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-- Step 1: Set the database to allow merge replication. EXEC s<a href="mailto:p_replicationdboption @dbname" >p_replicationdboption @dbname</a> = N'myDatabase', @optname = N'merge publish', @value = N'true'; -- Step 2: Create a merge publication. EXEC s<a href="mailto:p_addmergepublication @publication" >p_addmergepublication @publication</a> = N'myMergePublication', @description = N'Merge publication of database from publisher.'; -- Step 3: Add a table article for products to the publication. EXEC s<a href="mailto:p_addmergearticle @publication" >p_addmergearticle @publication</a> = N'myMergePublication', @article = N'products', @source_owner = N'dbo', @source_object = N'products'; |
Snapshot Replication in SQL Server: Code Example
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-- Step 1: Set the database to allow snapshot replication. EXEC s<a href="mailto:p_replicationdboption @dbname" >p_replicationdboption @dbname</a> = N'myDatabase', @optname = N'publish', @value = N'true'; -- Step 2: Create a snapshot publication. EXEC s<a href="mailto:p_addpublication @publication" >p_addpublication @publication</a> = N'mySnapshotPublication', @description = N'Snapshot publication of database from publisher.', @sync_method = N'snapshot'; -- Step 3: Add a table article for orders to the publication. EXEC s<a href="mailto:p_addarticle @publication" >p_addarticle @publication</a> = N'mySnapshotPublication', @article = N'orders', @source_owner = N'dbo', @source_object = N'orders'; |
Conclusion
SQL Server replication is a powerful tool to bring data to your fingertips wherever you require. It not only helps keep data up-to-date but ensures that your programs run smoothly by providing data locally. With replication types to suit different needs, it offers a robust and flexible framework for data management. Happy SQL-ing!