The Challenge

A leading organization in the freight & analytics industry operated a mission-critical Oracle RAC–based platform that handled massive daily workloads, including 20M+ transactions per day and over 1 billion events across systems. While schema conversion to PostgreSQL (via Ora2Pg) was already completed, the absence of an online migration mechanism left both environments, Oracle and PostgreSQL, perpetually out of sync.

This gap created serious risks: data divergence, unpredictable cutover timelines, inability to maintain alignment during active operations, and no real-time rollback path. Given the system’s scale - 9 Oracle databases totaling over 25TB - the organization needed a migration strategy that guaranteed safety, speed, and zero disruption.

The Solution

HexaCluster deployed HexaRocket, its enterprise-grade migration and real-time replication platform, to enable continuous synchronization and controlled cutovers. The core components of the solution included:

• Online Migration with CDC: Real-time replication from Oracle → PostgreSQL, keeping all 9 databases aligned even under heavy transaction loads.
• High-Volume Event Replication: Supported 1B+ events/day with <5 seconds replication lag on critical streams.
• Rollback Capability: Reverse CDC (PostgreSQL → Oracle) ensured instant fallback without data loss.
• Parallelized Processing: Multiple parallel workers per DB to meet the throughput demands of a >25TB footprint.
• Minimal Downtime:: Enabled switchover with <2 seconds downtime for mission-critical systems.
• Simplified Setup: Migration pipeline configured in minutes, requiring minimal supervision.

Implementation

• Environments: Environments: Rolled out across test, staging, and production clusters while managing multiple high-volume databases and RAC workloads.

• Phased Approach:

  1. Test Sync - Validated CDC, latency, and reverse-sync behavior pre-production.

  2. Staging Cutover - Conducted dry-runs with real workloads to assess readiness and tune worker parallelism.

  3. Production Migration - Executed full migration with continuous sync and a sub-2-second cutover window.

  4. Configuration: Calibrated parallel workers to maintain <5s replication lag during 20M+ daily transactions.

  5. Automated monitoring for replication health, lag spikes, table drift, and upstream Oracle RAC performance.

  6. Support Model: HexaRocket specialists provided real-time migration orchestration, performance tuning, and rapid incident response across all phases.

Results

• Zero-Downtime Migration: Successful switchover with <2 seconds downtime despite extremely high transaction volume.
• Massive Throughput Efficiency: Seamlessly handled 25TB+ datasets and 1B+ daily events with stable replication lag.
• Risk-Free Rollback:: Reverse-sync ensured immediate rollback capability, eliminating migration risk.
• Durable Scalability: Architecture easily scaled with additional workers to meet future load growth.

Key Benefits

• Continuous Data Integrity: CDC kept Oracle and PostgreSQL in perfect alignment throughout migration.
• Operational Confidence: Built-in rollback and real-time monitoring dramatically reduced cutover risk.
• Faster Project Timelines: Parallelism and simplified setup minimized manual work and accelerated delivery.
• Cost & Performance Efficiency: Transitioning away from Oracle RAC reduced licensing costs while enabling scalable open-source growth.

Next Steps

1. Complete the final production cutovers for remaining workloads.
2. Scale replication infrastructure as data volume grows.
3. Enable ongoing monitoring, tuning, and health audits to maintain optimal PostgreSQL performance.

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