A Comprehensive Guide To Migrating Databases From Oracle To Microsoft SQL Server


Organizations worldwide, regardless of their size and structure have typically used the Oracle Database Management System (DMS) to power their data-driven operations. However, there is now a growing demand for data storage and computing power as businesses diversify into various fields and grow exponentially. 

This steep rise in demand for resources has caught the users of traditional systems on the wrong foot. It is not possible to invest heavily in additional hardware and software every time there is a spike in demand for additional storage space. 

Fortunately, there is now a solution to get around this problem and get resources on demand within minutes by migrating to the cloud. The most optimized way is to move databases from Oracle to SQL server and get several benefits in the long run.

The Benefits of Moving Databases From Oracle to SQL Server

Let us now go through the benefits of this migration and the cutting-edge advantages it brings to the table. 

Low operating costs

For any business, keeping costs low gives a competitive edge and this is precisely what this form of migration aims to do. The cost involved in operating the Oracle CDC database is substantially more than SQL Server for the following reasons.

  • The cost of running the SQL Server is kept under control through data compression, consolidation of databases, and virtualizing servers. 
  • SQL Server does not require constant monitoring and hence recurring costs of hiring DBAs are limited.
  • SQL Server offers several editions with tiered pricing systems, allowing businesses to choose one that matches their requirements. 

For example, the enterprise edition packed with cutting-edge features is meant for large organizations and is highly priced. Mid-sized companies can pay less for the Standard edition which has fewer features and is less costly. Finally, the Express SQL version with minimal features is free which small businesses and startups can use to launch their operations and later move on to feature-packed editions. 

On the other hand, Oracle has Standard editions only at flat rates and features that you might not require but have to pay high rates for. 

Database performance

Database performance is considerably enhanced through the data compression facilities of SQL Server.  

Enhanced data safety

SQL Server uses encrypted and complex algorithms to increase data safety and security, a critical factor in the modern business environment. Layers of user access management systems firewall classified and confidential organizational data. 

Recovering lost or damaged databases

A very important benefit of Oracle to SQL Server database migration is the ability of the SQL Server to restore damaged databases into the system. 

To learn how the process works, it is necessary to understand the workflow of Oracle and SQL Server. While Oracle has log records written on a disk for all transactions, the SQL Server allows data storage and running queries through files, indexes, and transactions. In case of a crash, SQL Server uses these records to restore all the incomplete transactions from the time of the outage.  

Easy setup

The SQL Server can be easily set up and configured through a Setup Wizard without the need for any command-line configurations. All updates after the setup are automatically downloaded to the system.

Because of these benefits, more and more organizations are choosing to move databases from Oracle to SQL Server. 

Migrating Databases from Oracle to SQL Server

There are two distinct components of moving data from Oracle to SQL Server. The first is setting up the systems to prepare for the migration and the second is choosing the ideal method type that suits an organization the best. Each will now be seen in some detail.

Setting up the system for migration

  • Install SQL Server in the target database and make sure of unbroken connectivity between the target and the Oracle database at source.  
  • Install Oracle Client and SQL Server Migration Assistant (SSMA) in the target database system.
  • Check for firewall issues and port connectivity before running SSMA and linking to the Oracle source database. 
  • The Oracle schema must be mapped at the location where the migration will take place.
  • Finally, all Oracle database objects must be converted and loaded to the SQL Server either by running a script on the SQL server or synchronizing all database objects. 

After completing all these tasks, it is time to move on to the migration proper.  

Types of Oracle to SQL Server migration

There are two ways that this process may be carried out.

One-time method

Here, all systems are shut down while the migration process runs and the complete database is moved in one go. The reason for the downtime is otherwise, all incremental transactions made after the last migration run will not be reflected in the target database.

Even though this method is simple and the entire migration done at a time, there are downsides to it. The first is that test executions must be performed before starting the migration to make sure that no issues crop up during the process. Second, shutting down systems even for brief periods will adversely affect the operations of large data-driven enterprises. 

Phased migration method

This type of Oracle to SQL Server migration takes place over two stages. First, the entire migration is carried out just like the one-time method but with all systems running. Next, all the data generated in the source database after completing the first run migration is moved to the target database at pre-fixed intervals.In both methods, it is advisable to check whether there are any data type differences or mismatches once the movement of the database from Oracle to SQL Server is completed.