Informix to PostgreSQL Migration
Move your IBM Informix databases to PostgreSQL with a validated, low-risk migration, planned and delivered by database engineers who support Informix every day.
Why organisations move from Informix to PostgreSQL
Informix still runs many dependable production systems, from pathology and patient administration systems to logistics and finance applications. But the pool of engineers who know it is shrinking, licence and support costs keep rising, and many teams are unsure about its long-term roadmap. PostgreSQL is a mature, open-source relational database with a large skills base, strong standards support and fully managed options on every major cloud.
- Lower running costs: no per-core database licences, and a wide choice of support providers.
- Skills and hiring: PostgreSQL skills are far easier to find than Informix skills.
- Cloud options: run it yourself or use Amazon RDS and Aurora, Azure Database for PostgreSQL or Google Cloud SQL.
- A modern ecosystem: replication, JSON, full-text search, partitioning and a large extension library.
What changes when you move
Informix and PostgreSQL both follow standard SQL, so most tables and queries move across cleanly. The effort sits in a few well-understood areas:
| Informix | PostgreSQL | What it means |
|---|---|---|
| SPL stored procedures and functions | PL/pgSQL functions and procedures | Logic is converted and tested routine by routine; tooling handles much of the syntax. |
| SERIAL / SERIAL8 / BIGSERIAL | Identity columns or sequences | Sequence values are carried over so new keys continue from the right number. |
| DATETIME YEAR TO SECOND, INTERVAL | timestamp, interval | Precision and qualifiers are mapped column by column. |
| MONEY, DECIMAL | numeric | Mapped with matching precision to avoid rounding differences. |
| BYTE, TEXT, BLOB, CLOB | bytea, text | Large objects are extracted and reloaded with checksums. |
| Legacy OUTER join syntax | ANSI LEFT JOIN | Queries using the Informix-specific OUTER keyword are rewritten. |
| ROWID | Primary keys | Code relying on physical row IDs is changed to use keys. |
| ESQL/C and 4GL applications | ECPG (with an Informix compatibility mode), ODBC/JDBC, or application re-platforming | Assessed early, as applications are often the largest part of the work. |
How ONQU delivers an Informix 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.
Keep Informix running until you are ready
Most migrations need the existing system supported until the day of cut-over, and sometimes for read-only access afterwards. ONQU provides Informix support alongside the migration, so one team is accountable for both sides.
How long does it take?
It depends on data volumes, the amount of stored code and, above all, the applications involved. A single database behind one application can often move in weeks; a large estate with many applications and interfaces is usually a phased programme over several months. A Discovery Audit gives you a firm plan and estimate before you commit.
Frequently asked questions
How long does an Informix to PostgreSQL migration take?
A single database behind one application can often be migrated in a few weeks. Larger estates with many applications, interfaces and stored procedures are usually delivered in phases over several months. ONQU's Discovery Audit gives you a firm estimate before any work starts.
Can we migrate from Informix without downtime?
Downtime can be kept to a short, planned cut-over window. Data is loaded and validated in advance, and change-data capture can keep the new database up to date until the switch.
What happens to our Informix 4GL and ESQL/C applications?
They are assessed early, because applications are often the largest part of the work. Options include connecting them to PostgreSQL through ECPG, which has an Informix compatibility mode, or ODBC, or re-platforming the application. The right choice depends on how long the application needs to live.
Is PostgreSQL suitable for mission-critical systems?
Yes. PostgreSQL is used for mission-critical workloads across healthcare, finance and government, supports high availability and replication, and is offered as a fully managed service by all major cloud providers.
Can ONQU support Informix while we migrate?
Yes. ONQU supports Informix databases in production, so the existing system is looked after until cut-over and, if needed, afterwards for read-only access.
Can you migrate Informix to SQL Server or Oracle instead?
Yes. PostgreSQL is a common choice, but ONQU can also migrate Informix to Microsoft SQL Server, Oracle or a cloud database, depending on your standards and skills.
Get in touch
Please contact ONQU Support for a free, no obligation assessment.
