Oracle to PostgreSQL Migration: Complete Guide
Comprehensive step-by-step guide for migrating Oracle databases to PostgreSQL. Learn schema conversion, data type mapping, and performance optimization.
Why Migrate from Oracle to PostgreSQL?
Organizations migrate from Oracle to PostgreSQL to reduce licensing costs (save 80-90%), gain open-source flexibility, access modern features, and eliminate vendor lock-in. PostgreSQL offers comparable performance with better cost-efficiency and a vibrant community ecosystem.
Key Migration Challenges
Schema Differences
Oracle and PostgreSQL have different data types, constraints, and indexing strategies requiring careful mapping and conversion.
PL/SQL to PL/pgSQL
Stored procedures, functions, and triggers need rewriting from Oracle's PL/SQL to PostgreSQL's PL/pgSQL with syntax adjustments.
Performance Tuning
Query optimization differs between databases. Indexes, execution plans, and configuration parameters require PostgreSQL-specific tuning.
Data Validation
Ensuring 100% data accuracy during migration requires comprehensive validation, reconciliation, and testing strategies.
7-Step Oracle to PostgreSQL Migration Process
Assessment & Planning
Analyze Oracle database size, complexity, dependencies, and custom code. Identify migration risks and create detailed project plan.
- Inventory all database objects (tables, views, procedures, triggers)
- Assess data volume and growth patterns
- Identify application dependencies and integration points
- Define success criteria and rollback strategy
Schema Conversion
Convert Oracle DDL to PostgreSQL-compatible schema. Map data types, constraints, and indexes appropriately.
- Convert Oracle data types to PostgreSQL equivalents
- Migrate primary keys, foreign keys, and unique constraints
- Convert Oracle indexes to PostgreSQL B-tree/GiST/GIN indexes
- Handle Oracle-specific features (sequences, synonyms, packages)
Code Migration
Rewrite PL/SQL stored procedures, functions, and triggers to PL/pgSQL. Adapt Oracle-specific SQL syntax.
- Convert PL/SQL packages to PostgreSQL schemas
- Rewrite stored procedures and functions in PL/pgSQL
- Migrate triggers with PostgreSQL trigger syntax
- Update application SQL queries for PostgreSQL compatibility
Data Migration
Extract data from Oracle and load into PostgreSQL. Use efficient bulk loading techniques for large datasets.
- Export Oracle data using Data Pump or custom scripts
- Transform data formats and handle encoding differences
- Use COPY command for fast PostgreSQL bulk loading
- Implement incremental sync for large databases
Validation & Testing
Verify data accuracy, test application functionality, and validate performance against Oracle baseline.
- Row count and checksum validation
- Functional testing of all database operations
- Performance benchmarking and query optimization
- User acceptance testing (UAT)
Performance Optimization
Tune PostgreSQL configuration, optimize queries, and create appropriate indexes for production workload.
- Configure PostgreSQL memory settings (shared_buffers, work_mem)
- Analyze query execution plans and optimize slow queries
- Create missing indexes based on query patterns
- Set up connection pooling (PgBouncer)
Cutover & Monitoring
Execute final cutover to PostgreSQL, monitor performance, and provide post-migration support.
- Final data sync and validation
- Switch application connections to PostgreSQL
- Monitor database performance and error logs
- Provide hypercare support for 2-4 weeks
Oracle to PostgreSQL Data Type Mapping
Common data type conversions from Oracle to PostgreSQL
| Oracle Data Type | PostgreSQL Equivalent | Notes |
|---|---|---|
| VARCHAR2(n) | VARCHAR(n) | Direct mapping |
| NUMBER | NUMERIC | Use NUMERIC for precision |
| NUMBER(p,s) | NUMERIC(p,s) | Exact precision match |
| DATE | TIMESTAMP | Oracle DATE includes time |
| TIMESTAMP | TIMESTAMP | Direct mapping |
| CLOB | TEXT | PostgreSQL TEXT is unlimited |
| BLOB | BYTEA | Binary data storage |
| RAW | BYTEA | Binary data |
| LONG | TEXT | Deprecated in Oracle |
| ROWID | OID or CTID | Use surrogate keys instead |
AI-Powered vs Manual Oracle to PostgreSQL Migration
See how DataMigration.AI automates Oracle to PostgreSQL migration
| Feature | DataMigration.AI | Manual Migration |
|---|---|---|
| Schema Conversion | Automated with AI validation | Manual DDL rewriting (2-4 weeks) |
| Data Type Mapping | Intelligent mapping with edge case handling | Manual mapping prone to errors |
| PL/SQL to PL/pgSQL | AI-assisted code conversion | Manual rewrite (4-8 weeks) |
| Data Migration Speed | 1TB in 4-6 hours | 1TB in 24-48 hours |
| Validation | Automated row-by-row comparison | Manual sampling (incomplete) |
| Downtime | Near-zero with CDC | 4-12 hours typical |
| Total Timeline | 2-4 weeks | 8-16 weeks |
| Cost (100GB database) | $8K-$15K | $40K-$80K |
| Success Rate | 99.5% first-time success | 70-80% (multiple attempts) |
| Post-Migration Support | AI-powered monitoring & optimization | Manual troubleshooting |