Oracle database solution has been the workhorse of data-driven organizations for more than 4 decades now. Then where is the need to migrate databases from Oracle to SQL Server? The answer is simple. The high costs of running and maintaining Oracle databases are deterrents in today’s business environment where keeping the costs of database solutions low is one of the primary goals. For example, in Oracle, users have to pay for partitioning a table and for availing of advanced features like Database Encryption or Dynamic Data Masking. On the other hand, all these features are available out of the box in the Enterprise Edition of SQL Server.
Apart from the cost factor, as a user, you also can avail technologically advanced tools to facilitate the Oracle to SQL Server database migration process. One of them is the SQL Server Migration Assistant (SSMA tool) provided in almost all Microsoft SQL Server versions.
Why Should You Migrate Databases from Oracle to SQL Server?
There are several reasons for migrating databases from Oracle to SQL Server.
- While, as discussed, Oracle is pricier to run and maintain, costs are kept under control in SQL Server through data compression, virtualizing servers, and consolidating databases. Expenses are further reduced as SQL Server is more user-friendly than Oracle and does not require any human intervention by DBAs to operate.
- SQL Server operates within a network of encrypted and complex algorithms, thereby making sure of high data safety and security. Stringent permission management systems and tracking of user access ensure the protection of all classified and sensitive business data.
- The performance of databases in SQL Server is significantly increased through an optimized and transparent data compression facility.
- Setting up and installing SQL Server can be easily done through a Setup Wizard. It does not require any command-line configuration and updates are downloaded automatically.
- One of the main reasons for companies migrating databases from Oracle to SQL Server is that Microsoft offers different editions to complement user requirements. The Enterprise SQL Server edition with its advanced features is perfect for large organizations while small and mid-sized businesses can avail of the Standard edition. There is also the free Express SQL Server version that has limited features and is suitable for Startups and individuals. Each is priced as per the level of sophistication and number of features.
- SQL Server is very effective in recovering damaged or lost databases. Complete databases can be restored and this is considered to be one of the top capabilities of the SQL Server. It is possible because the database engine of the SQL Server enables storage and running queries through indexes, files, and transactions. Log records are entered on the disk before committing a transaction and this is an advantage that SQL Server has over Oracle. In case the server hardware, the operating system, or even a database engine instance fails in SQL Server, the transaction logs are used by the instance after the issue is resolved to bring the incomplete and cut-off transactions back to the place where the outage occurred.
- When compared to the Oracle database, the running and operating costs of the SQL Server are quite low,inclusive of very affordable features like data mining and partitioning. This aspect is also true for tools used in data maintenance and data storage.
All these features make Oracle to SQL Server migration of databases a very attractive proposition for businesses.
Preliminary Processes for Oracle to SQL Server migration
Before initiating the process of migration, a few preparatory activities have to be carried out.
- The SQL Server has to be installed at the intended target where the data has to be migrated. Next, proper connectivity has to be established between the Oracle source database and the Microsoft SQL Server target database.
- Both Oracle Client and SSMA (SQL Server Migration Assistant) have to be installed and configured in the target database.
- All issues related to the port and the firewall have to be verified before the SSMA is launched and linked to the source database.
- The Oracle schema has to be mapped to the target location where the database Oracle to SQL Server has to be migrated.
- All the Oracle database objects have to be converted and loaded to the SQL Server by either syncing all the database objects or saving a script and applying it to the SQL Server.
These activities are essential before starting on the Oracle to SQL Server database migration. These steps have to be followed also before migrating an Oracle database to Azure SQL database and Azure Synapse Analytics.
Migrating Databases from Oracle to SQL Server
There are two methods to migrate databases from Oracle to SQL Server.
- One-time method: This method is relatively simple and completed in one go. All systems are shut down and the complete migration is done at a time. Hence, downtime is required as otherwise, transactions that have taken place since the last run will not be reflected in the target database. Test executions should be done before the migration proper to ensure that there are no hitches once the migration starts. This method though is often not suitable for large data-driven organizations as shutting down systems even for short periods might adversely affect their operating efficiencies.
- Phased migration: This Oracle to SQL Server migration process is a two-step one. First, data is completed migrated between the source and the target without shutting down the systems. Once completed, all incremental data and changes that have taken place after the first phase is completed are loaded to the target database at pre-determined intervals.
It is up to individual businesses to choose one of the two as per their convenience.