The article provides a comprehensive guide to those considering database migration from Oracle to PostgreSQL. It highlights the benefits of using PostgreSQL as a database system, such as cost-effectiveness, flexibility, and customizability. The overall process of migration can be arranged into several phases:
- assessment
- schema migration
- functional and performance testing
- data migration
- database logic and application layer migration
The whitepaper also explores key distinguishes between the two database management systems to help users avoid common mistakes. In addition, it offers alternative migration strategies and lists free data migration tools that can be helpful in the process.
PostgreSQL offers numerous advantages over Oracle databases in terms of application programming, authentication, extensibility, languages, localization, performance, and scalability. However, it’s important to note that migrating from Oracle to PostgreSQL can be a challenging and time-consuming process due to the differences in their relational database management systems (RDBMS) structure and data types. Therefore, it’s crucial to approach the migration process with the right tools and follow the recommended steps to ensure a successful migration.
The initial stage of planning a migration from Oracle to PostgreSQL involves conducting an assessment of the application to determine the level of difficulty involved in the migration process. This stage requires a comprehensive analysis of technology-related factors such as client, application server, data access, and database features to evaluate compatibility. The next step is schema migration, which involves converting the Oracle schema to PostgreSQL. Before proceeding with the migration, it is crucial to conduct thorough testing of the converted schema using a sample dataset. This is followed by performance testing to identify any differences and fixing them at the application, data access (drivers), and database level through proper tuning.
There are multiple data migration approaches and tools available in the market, which can generally be classified into three types:
- Snapshot
- Piecewise (parallel) snapshot
- Change Data Capture (Replication)
The first two approaches involve moving data from Oracle to PostgreSQL in a one-time transfer, while the third approach continuously loads data. This leads to smaller downtime windows. In order to avoid broken corporate data flow, person responsible for database migration must carefully choose the right approach that fits the downtime window.
In the Snapshot approach, the source database state is captured as a snapshot and applied to the target database all at once. The data is moved from Oracle to PostgreSQL in one shot. During the snapshot process, no WRITE operations are allowed on the source database, resulting in application downtime. However, it’s a cleaner and simpler method of data migration. The Piecewise (parallel) snapshot approach is a variation of the Snapshot approach, where data objects are split into chunks, and snapshots are taken in parallel. This approach significantly reduces the snapshot duration and downtime window. Good scripting skills are required to prepare data migration tools for table or large table migration. Change Data Capture (Replication) is a continuous migration approach where data changes on the source database are continuously transferred to the target database. This approach has a lower downtime window than the Snapshot approach.
In conclusion, migrating from Oracle to PostgreSQL offers many benefits such as cost-effectiveness, flexibility, and customizability. The migration process, although challenging, can be successful if approached with the right tools and following the recommended steps. The article provides a detailed guide on the migration process, including assessment, schema migration, intermediate testing, data migration, and final testing. It also identifies key differences and incompatibilities between the two database systems to help users avoid common mistakes. Additionally, the article offers alternative migration strategies and lists free data migration tools that can be helpful in the process.
