PostgreSQL to Oracle: Migration With No Hassle

When it comes to databases, the first relational databases that come to mind are Oracle and PostgreSQL. Both are leaders in the number of downloads and usage in the enterprise.

But just like any software, any database has strengths and weaknesses. That is why the issue of migration inevitably arises at some point in any organization.

Today we will analyze a complex and controversial topic that many managers have in their nightmares – migrating databases from PostgreSQL to Oracle. Is it even worth touching something that already works? Is it worth migrating? How long will it take? What resources are essential for a successful modernization project?

Why migrate PostgreSQL to Oracle?

The choice of migrating from free and open source PostgreSQL to commercial Oracle may seem controversial. However, such migration has a number of advantages. Let’s review some of them:

  •  Enhanced performance. Oracle databases are known for their performance. They can handle large volumes of transactions and complex queries with amazing efficiency. If your business is growing fast and your PostgreSQL database is struggling, Oracle performance can help keep things running smoothly.
  • Advanced security features. In an age where cybercrimes happen every 2 minutes, security is more important than ever. Therefore, the security measures that Oracle offers today are worth their weight in gold. Among the most important are modern encryption methods, access control, and comprehensive auditing capabilities. All this ensures that Oracle protects your data and comply with industry standards and regulations.
  • Scalability. As business grows, so does the amount of data you need to manage. Oracle is designed to scale effortlessly, accommodating increasing data loads without compromising on performance. This scalability ensures that your database can grow alongside your business, supporting its expansion and future needs.
  • Comprehensive support and resources. Oracle offers extensive support and a wealth of resources for its users. From detailed documentation to a global community of experts, you have access to any help you may need. This support network may be invaluable when solving complex database issues or implementing new features.
  • High availability and disaster recovery. Oracle boasts robust architecture that ensures high availability. In fact, it means that your database can deliver consistent performance with minimal downtime. Additionally, it has disaster recovery solutions that can protect your data from unexpected events, ensuring business continuity even in the face of disasters.
  • Advanced analytics and reporting. Oracle’s advanced analytics and reporting capabilities can provide deeper insights into your data. With powerful tools like Oracle Analytics Cloud and Oracle Business Intelligence, you can uncover trends, make data-driven decisions, and gain a competitive edge in your industry.

Schema conversion: a key step in PostgreSQL to Oracle migration

Converting SQL is a challenging and crucial task in the migration process from PostgreSQL to Oracle. This stage demands meticulous attention and expertise from the development team due to the numerous critical differences between the two database systems. Successfully navigating these differences ensures that your applications and data operations continue to function seamlessly post-migration. Here are some potential difficulties that may arise during the conversion and how they can impact the migration project:

  • Collections. Collections in Oracle (such as VARRAYs, nested tables, and associative arrays) offer powerful ways to handle sets of data within PL/SQL. Arrays and composite types of PostgreSQL serve similar purposes but differ in implementation and syntax. Converting these data structures necessitates careful mapping to ensure that the logic and performance of the original PostgreSQL code are preserved.
  • Dynamic SQL. One of the primary difficulties with dynamic SQL is ensuring that the dynamic queries perform efficiently in the new environment. The development team must rewrite these dynamic queries to leverage Oracle’s performance features while maintaining the logic and intent of the original PostgreSQL code.
  • Working with geography. Geospatial data handling is another area with significant differences. PostgreSQL’s PostGIS extension is a powerful tool for geographic objects and spatial queries. Oracle Spatial and Graph provide similar functionalities but with different syntax and capabilities. Migrating geospatial data involves translating spatial functions and ensuring that spatial indexes and queries perform optimally in the Oracle environment.
  • Transactions and exceptions. Handling transactions and exceptions also varies between PostgreSQL and Oracle. PostgreSQL uses standard SQL for transactions but has different mechanisms for exception handling in PL/pgSQL. Oracle’s PL/SQL provides robust transaction control and exception handling features, but the syntax and behavior can differ. Maintaining data integrity and application reliability during migration requires preserving transaction boundaries and exception handling logic.

Migrating Data

Data migration is another critical phase in the process of moving from PostgreSQL to Oracle. The accuracy and efficiency of transferring data to the new database will depend on how the data migration is performed.

Data migration may be challenging due to differences in data types and formats between PostgreSQL and Oracle. This can make transferring data between the two systems difficult. As the data moves from one system to the other, it often needs to be transformed to fit the requirements of the new database. This transformation process is essential to ensure that data remains accurate and functional after the migration.

Data migration involves verifying that the data in Oracle aligns with the data in PostgreSQL, along with import and export processes. This includes checking that all records have been transferred correctly and that there are no discrepancies. Validation helps to maintain trust in the data and ensures that the new database can be relied upon for business operations.

A key point to remember at this step of the migration is that data migration is about more than just moving data from one place to another. The process involves changing and checking the data to ensure it functions properly in the new system. The goal is to minimize any disruptions that may occur during this transition.

Testing stage

The testing stage following a migration is critical to ensure the integrity and functionality of the migrated system. During this phase, the primary difficulties include verifying data accuracy, ensuring system compatibility, and validating performance in real-world conditions.

Testing is usually carried out in two steps – functional testing and stress testing. Functional testing ensures that all applications and processes that rely on the database function correctly in the Oracle environment. This involves executing test cases that cover typical use cases and edge cases to validate that the applications perform as expected. This involves testing SQL queries, stored procedures, and triggers to make sure they give the right results and follow business rules.

Stress testing involves subjecting the new Oracle environment to simulated high-demand scenarios to assess its stability and performance under extreme conditions. By pushing the system beyond its normal operational limits, stress testing helps identify potential weaknesses, bottlenecks, or scalability issues that need to be addressed before full deployment, ensuring optimal performance during peak usage periods.


This article offers a guide on migrating databases from PostgreSQL to Oracle. It outlines the key subtleties involved in database migration. Although the process of migrating databases is not easy, it can be automated so as not to spend months or even years on manual conversion.

Ispirer Toolkit offers a comprehensive solution for PostgreSQL to Oracle migration, including automated schema conversion, data transfer, error handling, and customization options. Furthermore, this database migration tool comprehensive reports and customization opportunities empower users to address migration challenges effectively and ensure a smooth transition to Oracle.

Alex Kirpichny is the Chief Product Officer at Ispirer Systems, responsible for developing the company’s solutions with a focus on innovation and market demands.

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