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More and more enterprises are finding that the high licensing costs, strong vendor lock-in, and complex operation and maintenance processes of Oracle databases can no longer meet the cost control and agility requirements of the cloud-native era. As a mature managed relational database service in the AWS ecosystem, Amazon RDS for PostgreSQL has become the preferred target for enterprises to break away from Oracle constraints, thanks to its fully managed operations, elastic scalability, and open-source compatibility. However, migrating from Oracle to Amazon RDS PostgreSQL is not a simple data transfer. Schema differences, PL/SQL code adaptation, and zero-downtime business requirements all require professional migration tools and strategies to achieve a smooth transition.
Amazon RDS for PostgreSQL is a fully managed database service built by AWS based on open-source PostgreSQL. It retains the open-source features and compatibility of PostgreSQL while adding the advantages of AWS cloud services, providing enterprises with an out-of-the-box database solution without the need to focus on underlying infrastructure management.
Key Reasons Enterprises Choose RDS for PostgreSQL
These features make RDS for PostgreSQL an ideal target for enterprises migrating from Oracle. But before the actual migration, it is also necessary to clarify the differences between it and Aurora PostgreSQL, another PostgreSQL-compatible service of AWS, to avoid selection deviations.
AWS offers two PostgreSQL-compatible services, both built based on open-source PostgreSQL, but there are obvious differences in architectural design, performance, and cost. Enterprises need to choose according to their own business scale and requirements.
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Consideration Factor |
Scenarios for Prioritizing RDS for PostgreSQL |
Scenarios for Prioritizing Aurora PostgreSQL |
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Cost Control |
Small and medium-sized businesses, department-level applications, or test environments pursuing low TCO |
Enterprise core businesses, high-concurrency scenarios where higher costs are acceptable for better performance |
|
Business Scale |
Single-instance data volume < 10 TB, daily transaction volume < 1 million |
Single-instance data volume > 10 TB, daily transaction volume > 1 million |
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Architecture Complexity |
Prefer simple deployment without the need for distributed storage or cross-region synchronization |
Need distributed storage, global multi-region deployment, or second-level cross-region replication |
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Performance Requirements |
Medium read/write performance without extreme low-latency requirements (millisecond-level response is sufficient) |
High read/write performance requirements, needing microsecond-level response or high-throughput support |
For example, a regional inventory management system of a retail enterprise with a small data volume and high cost sensitivity is suitable for RDS for PostgreSQL; while a core transaction system of a financial enterprise requiring high availability and low latency is more suitable for Aurora PostgreSQL. After clarifying the selection, enterprises also need to address various technical challenges during the migration process.
Migrating from Oracle to RDS PostgreSQL is essentially a technology stack switch from a “closed-source commercial database” to an “open-source managed database”. The differences between the two in data types, syntax rules, and functional features will bring multi-dimensional migration challenges.
►When mapping Oracle’s NUMBER type (supporting arbitrary precision) to PostgreSQL’s NUMERIC type (with limited default precision), precision loss is prone to occur. There are differences in storage logic between CLOB/BLOB types and PostgreSQL’s TEXT/BYTEA types, which require additional processing.
►Different case sensitivity rules: Oracle is case-insensitive to table/column names by default, while PostgreSQL is case-sensitive by default. If not configured in advance, queries will fail after migration.
►Oracle relies on PL/SQL to implement stored procedures, triggers, and functions, while PostgreSQL uses PL/pgSQL. The two have similar syntax but are incompatible (such as the difference between Oracle’s %ROWTYPE and PostgreSQL’s RECORD type).
►If an enterprise has a large amount of historical PL/SQL code (such as risk control calculation logic in the financial industry), manual refactoring will consume a lot of development resources and is prone to introducing bugs.
►Oracle supports various advanced partitioning strategies such as range partitioning, hash partitioning, and list partitioning. Some strategies (such as interval partitioning) need to be implemented through extensions (such as pg_partman) in PostgreSQL and cannot be migrated directly.
►Index type differences: Oracle’s bitmap index has no corresponding type in PostgreSQL and needs to be replaced with B-tree index or GIN index, which may affect query performance.
►If the Oracle database has a data volume of TB level, the traditional batch export (such as expdp) + import (such as psql) method is time-consuming (it may take more than 24 hours). During this period, the business cannot be interrupted, which is likely to lead to data inconsistency between the source database and the target database.
►Oracle data continues to change during migration (such as new orders and updated user information). Real-time change capture and synchronization to RDS are required; otherwise, the problem of “data expiration as soon as migration is completed” will occur.
►Core businesses (such as e-commerce transactions and payment systems) cannot afford long-term downtime. If the “stop service first, then migrate” method is adopted, it will directly affect revenue and user experience. However, traditional tools are difficult to achieve “non-stop service synchronization”, resulting in high downtime risks.
If these challenges are only solved by manual work or basic tools, it will not only extend the migration cycle (which may drag on from weeks to months) but also may cause data loss, performance degradation, and other problems. At this time, choosing a suitable migration tool has become the key to breaking through the bottleneck. Traditional migration solutions often have obvious limitations and are difficult to cover the core needs of enterprises.
In the initial stage of migration, enterprises often try to use AWS native tools, manual operations, or third-party commercial tools, but these solutions often show problems of low efficiency and high risk when dealing with complex scenarios.
►Working Logic: Scan Oracle schema through SCT and convert it into PostgreSQL format, then complete batch data migration and CDC synchronization through DMS.
►Limitations: The conversion rate of SCT for complex PL/SQL code is less than 50%, requiring a lot of manual code rewriting. DMS is prone to synchronization delays in high-concurrency scenarios (such as peak transaction volume > 10,000 transactions/second) and does not support automatic handling of schema changes.
►Working Logic: Export data as dump files through Oracle’s expdp tool, then import them into the target database through PostgreSQL’s psql tool.
►Limitations: Only applicable to non-core scenarios with data volume < 100 GB; long downtime (it takes hours for 100 GB of data); no change synchronization capability; new data in the source database during migration needs to be manually supplemented.
►Working Logic: Write scripts based on Python/Java, or use ETL tools such as Talend and Informatica to implement the “extract-transform-load” process.
►Limitations: Long development cycle (2-4 weeks are needed to build a basic pipeline); only supports batch synchronization, not real-time CDC; scripts need to be modified again when the schema changes, resulting in high maintenance costs.
►Working Logic: Capture Oracle changes through log parsing technology, synchronize them to RDS PostgreSQL in real time, and support complex data conversion.
►Limitations: Annual licensing fees can reach hundreds of thousands or even millions of yuan, offsetting the cost advantages of migrating from Oracle. The integration with the AWS ecosystem is low (such as inability to automatically adapt to RDS parameter configuration), requiring additional development of adaptation modules.
The common problem of traditional solutions is that they cannot meet the four core requirements of “real-time synchronization”, “low code”, “low cost”, and “zero downtime” at the same time. For example, DMS can achieve CDC but has poor adaptability; GoldenGate has complete functions but high cost; manual operation has low cost but is only suitable for small scenarios. These limitations make enterprises realize that they need a migration tool specially designed for the “Oracle to RDS PostgreSQL” scenario. i2Stream from information2 software is a solution launched to address these pain points.
Unlike traditional tools, i2Stream is a real-time data integration platform launched by information2 software, specially designed for enterprise-level database migration, especially suitable for the scenario of migrating from Oracle to Amazon RDS for PostgreSQL. It can solve the pain points of traditional solutions through “unified pipeline + intelligent adaptation” and achieve the migration goal of “near-zero downtime, no code, and high reliability”.
►Read Oracle archive logs through LogMiner technology, and complete “historical data backfill” and “real-time change capture” at the same time without splitting into two tools.
►Automatically identify the schema structure and data types of Oracle, intelligently map them to PostgreSQL (such as automatically adjusting NUMBER type precision and handling case issues), reducing manual intervention.
►Automatically create target tables in RDS PostgreSQL (matching the table structure and indexes of Oracle), and support custom schema mapping (such as mapping the “SCOTT” user table of Oracle to the “public” schema of PostgreSQL).
►Provide “Delta Updates” and “Hard Deletes” functions to ensure that the add, delete, and modify operations of the source database are synchronized to the target database in real time.
►During migration, i2Stream keeps Oracle and RDS PostgreSQL data synchronized continuously. Enterprises can verify the data accuracy of the target database at any time (such as comparing data of both ends through the data verification function).
►Only 1-2 minutes of Oracle write suspension is required during cutover (to ensure the synchronization of the last batch of changes), and then the business traffic can be switched to RDS PostgreSQL, achieving near-zero downtime.
For enterprises facing migration challenges, i2Stream can not only solve technical pain points but also shorten the migration cycle and reduce migration costs.
Migrating an Oracle database to Amazon RDS PostgreSQL can be a complex task, but using i2Stream from information2 Software can simplify this process. Below are the basic steps for using i2Stream to perform the migration:
Step 1. Environment Preparation:
►Ensure network connectivity between the source (Oracle) and target (Amazon RDS PostgreSQL) environments.
►Install the i2Stream client on the source end.
►Configure the Amazon RDS PostgreSQL instance to meet the migration requirements.
Step 2. Configure i2Stream:
►According to the documentation, configure i2Stream by specifying the connection details of the source database (Oracle), such as IP address, port, username, password, etc.
►Specify the connection details of the target database (Amazon RDS PostgreSQL).
►Set the tables or schemas that need to be synchronized.
Step 3. Data Initialization:
►Use the data initialization feature of i2Stream to migrate data from Oracle to PostgreSQL in a single operation. This step is typically performed during a low-traffic period to minimize impact on the production system.
Step 4. Incremental Synchronization:
►Enable the incremental synchronization feature of i2Stream to capture changes on Oracle and sync them in real-time to PostgreSQL starting from the completion of data initialization.
Monitor the synchronization status to ensure data consistency.
Step 5. Switch Application:
►Once it is confirmed that the data has been fully synchronized and is consistent, switch the application’s database connection to the new PostgreSQL database at an appropriate time.
Perform necessary tests to ensure the application runs smoothly.
Step 6. Validation and Optimization:
►After the switch, continuously monitor the performance of PostgreSQL and adjust parameter settings as needed.
►Conduct performance testing on the application to ensure the migrated system meets performance requirements.
For more detailed steps on how to use i2Stream, please watch this video. If you’d like to learn more, please request a demo.
After completing the migration from Oracle to RDS PostgreSQL, enterprises also need to optimize the target end to ensure stable business performance. At the same time, common questions during the migration process need to be clarified in advance to avoid subsequent operation and maintenance risks.
Migrating from Oracle to Amazon RDS for PostgreSQL is an important step for enterprises to reduce IT costs, get rid of vendor lock-in, and embrace the open-source ecosystem. However, the technical challenges during the migration process (such as schema adaptation, PL/SQL refactoring, and zero-downtime requirements) are difficult to solve efficiently only by traditional tools. i2Stream from information2 software provides enterprises with a simpler and more reliable migration solution through the core capabilities of “real-time CDC + automatic adaptation + zero-code configuration”, helping enterprises shorten the migration cycle and reduce operation and maintenance risks.
If your enterprise is planning to migrate from Oracle to RDS PostgreSQL, you can start with the following actions: