Migrating Databases Oracle to SQL Server – Process and Challenges

In the current business ecosystem, it is not uncommon to find mid to large-sized organizations using the Oracle database as a part of their database management environment. However, with data and business volumes growing exponentially, the traditional database architectures are being overwhelmed and stretched to their limits as there is a massive requirement for additional storage repositories and computing powers. 

A key approach to mitigating this problem is migrating databases from on-premises to the cloud. But first, it is necessary to understand and evaluate which platform is ideal for fueling rapid growth, the performance levels, and the operational benefits that can be had at an optimized cost structure. One of the most preferred options for on-premises databases is Oracle to SQL Server migration. 

The need for Oracle to SQL Server migration

Several benefits can be had for Oracle to SQL Server migration.

    When compared to SQL Server, Oracle database is relatively costlier if all the features like Oracle enterprise manager or Oracle data guard are used. SQL Server, on the other hand, offers all advanced database engine features like Analysis Services or Reporting Services in one license cost. 

    SQL Server is more robust in handling massive volumes of data for processing loads and running applications that are important to meet organizational goals. This is one of the main reasons for Oracle to SQL Server migration.

    Oracle users get locked into a single vendor with high licensing costs that are especially felt at times of upgrading or modernizing existing infrastructure and systems. But with Microsoft SQL Server, the same customers can get the desired performance, scale, and security needed to run enterprise-level applications at affordable costs. 

    Costs are kept within reasonable limits and control through merging databases, visualizing servers, allotting resources optimally, and compressing data, thereby making for more streamlined and seamless data policies. 

    Exclusive reporting systems can be created by utilizing the unique automated business intelligence attributes of SQL Server, thereby reducing the dependence on IT and database administrators. 

It is clear now why Oracle to SQL Server migrationis required to optimize operational efficiencies.

Steps for Oracle to SQL Server migration.

Before starting the main work of migrating database Oracle to SQL Server, a few preliminary steps have to be followed.

    SQL Server has to be installed on the target database where the migrated database will be hosted. Proper accessibility and connection have to be ensured between the Oracle source database and the target SQL Server database. 

    Both Oracle Client and SQL Server Migration Assistant (SSMA) have to be installed on that server.

    The connectivity to the port and other firewall issues need to be checked before launching SSMA and linking it to the oracle database at the source.

    The Oracle schema has to be mapped to the point where migration to SQL Server has to be done.

    Oracle objects have to be converted and loaded to SQL Server either by saving a script and running it on SQL Server or synchronizing the database objects. 

    Finally, carry out Oracle to SQL Server migrationand update all database applications. 

This process holds goodfor Oracle to Azure SQL database and Azure Synapse Analytics apart from Oracle to SQL Server migration

Methods of Oracle to SQL Server migration

There are mainly two methods of Oracle to SQL Server migration

    In the first case, the entire migration is completed at a time, and therefore, this process is called the one-shot method. The current systems have to be shut down during migration. If this is not done, transactions that occur after the last backup has been taken will not be moved to the new target database. However, while this is a quick and seamless operation, the downside is that systems have to be shut down and this is not always possible in mid and large-size organizations. Before this migration method is adopted, several test executions have to be undertaken to make sure that there is no glitch on migration day. 

    The second method involves two steps and is called the phased migration approach. First, the focus is on Oracle to SQL Server migrationof data that does not change or rarely does so. Once this is completed, migration of data is done at preset intervals of any incremental data that comes up after the last run.   

The method chosen by a business depends on specific and exclusive business requirements. 

Challenges Faced for Oracle to SQL Server migration

Even though the process of database Oracle to SQL Server migrationis largely automated there are several challenges that might crop up along the way. Here are some that you should focus on during migration and after.

    Oracle to SQL Server migrating indexes: Even though an index appears to be another object in the database, it sits in different ways in Oracle and SQL Server. Hence, examine the logical layout of the tables by focusing on the use cases of the data to create an optimized indexing strategy.  

    Checking database performance after migration: Check the performance of the database after migration on your load harness with the SQL Server Distributed Replay feature. Determine if the technology is sized properly by tracking the system when it is under pressure and evaluate if resources have to be reallocated. 

    Unique migration issues: Review the schemas in each Oracle instance to check data type mismatches and differences after Oracle to SQL Server migration.  

    Testing converted code: Verify the converted code to make sure that the data is in the format and the order that the organization is used to.  

This is the process of Oracle to SQL Server migration and the challenges faced by businesses.