Oracle to PostgreSQL Migration
Cut Oracle licence costs by moving to PostgreSQL, with PL/SQL converted, data validated table by table and a planned cut-over from engineers who support both.
Why move from Oracle to PostgreSQL
Oracle Database is powerful, but its licensing and support costs are among the largest items in many IT budgets. PostgreSQL offers enterprise-grade features without licence fees, runs anywhere, and is available as a managed service on every major cloud.
- Licence savings: no per-processor database licences or options packs.
- Flexibility: on premises, any cloud, or a managed service such as Amazon Aurora, Azure Database for PostgreSQL or Google Cloud SQL.
- Compatibility help: the open-source orafce extension provides many Oracle-style functions, easing code conversion.
- Tooling: mature migration tools such as ora2pg and cloud migration services speed up schema and data conversion.
What changes when you move
| Oracle | PostgreSQL | What it means |
|---|---|---|
| PL/SQL packages, procedures, functions | PL/pgSQL functions and procedures; packages become schemas | The largest conversion task; automated tools help, engineers finish and test. |
| NUMBER, VARCHAR2, CLOB, BLOB | numeric / integer / bigint, varchar, text, bytea | Types mapped per column for correctness and performance. |
| DATE (includes time) | timestamp(0) | Avoids silently losing the time component. |
| Empty string treated as NULL | Empty string and NULL are different | Queries and constraints relying on Oracle’s behaviour are reviewed. |
| CONNECT BY hierarchical queries | Recursive common table expressions (WITH RECURSIVE) | Rewritten and tested against real data. |
| ROWNUM, DUAL, synonyms | LIMIT / row_number(), plain SELECT, search_path or views | Common patterns converted automatically. |
| Autonomous transactions, DBMS_ packages | Extensions or redesign | Assessed individually; some need a different design. |
| Oracle Forms, APEX and other front ends | Modern web front ends or reconnected applications | Planned alongside the database; see Oracle Forms migration. |
How ONQU delivers an Oracle migration
- Discovery Audit. We inventory databases, schemas, stored code, interfaces, batch jobs and the applications that connect to them, and size the effort and risk before you commit.
- Schema and code conversion. Tables, indexes, constraints and stored procedures are converted with automated tooling, then reviewed and corrected by our engineers where the tools fall short.
- Scalable Proof of Concept. We migrate a real, representative slice of your data and application first, so performance, behaviour and the plan are proven early.
- Data migration and validation. Full data loads with row counts, checksums and business-level reconciliation reports, so every table is signed off with evidence.
- Parallel running and cut-over. Rehearsed cut-overs, a tested rollback plan and, where needed, change-data capture to keep downtime to a planned window.
- Support after go-live. We support the new platform, and can keep supporting the old one until it is safely decommissioned.
Not every Oracle system should move
Some systems depend on Oracle-specific features or third-party software certified only on Oracle. Our Discovery Audit tells you which databases will benefit from moving and which are better kept on Oracle, and we continue to provide Oracle Database support for those that stay.
Frequently asked questions
How much can we save by moving from Oracle to PostgreSQL?
Savings come mainly from removing Oracle licence and support fees, and depend on your edition, cores and options. A Discovery Audit sets the expected savings against the migration effort for each database.
How long does an Oracle to PostgreSQL migration take?
A straightforward database can move in weeks; systems with extensive PL/SQL, packages and connected applications are typically delivered in phases over several months.
Will our PL/SQL work in PostgreSQL?
Not unchanged, but PL/pgSQL is similar in style. Tools such as ora2pg convert much of it automatically, the orafce extension provides many Oracle-compatible functions, and our engineers convert and test the rest.
Can we move Oracle to PostgreSQL in the cloud?
Yes. Common targets include Amazon RDS or Aurora PostgreSQL, Azure Database for PostgreSQL and Google Cloud SQL, as well as self-managed PostgreSQL.
What about Oracle Forms applications?
They are planned alongside the database. ONQU migrates Oracle Forms to modern web frameworks such as React or Angular, or can keep them running while the database moves.
Should every Oracle database move?
No. Some systems depend on Oracle-only features or vendor certification. The Discovery Audit identifies which databases to move and which to keep, and ONQU supports both.
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Get in touch
Please contact ONQU Support for a free, no obligation assessment.
