Case study
Multi-Tenant Migration with Progressive Cutover
Migrated 150 tenants (10M rows) across 20 progressive waves with complex FK dependencies.
Architecture diagram
Wave-based multi-tenant migration
A controlled migration operating model with dual writes, tenant-aware routing, automated reconciliation, and rollback paths.
Legacy tenant stack
150 tenants, 10M rows, 30+ tables
Risk grouping
Wave planner
Grouped by tenant size and risk
Cutover window
Dual-write layer
Writes mirrored during transition
Safe transition
FK-safe loader
Dependency-ordered table migration
Ordered load
Modern multi-tenant DB
Validated target environment
Reconciled state
Feature-flag routing
Tenant reads shift after validation
- Row counts, checksums, and business-rule validation replaced manual spot checks.
- Feature flags made read cutover tenant-specific and reversible.
- Wave cadence reduced incident blast radius and improved rollback confidence.
The challenge
Migrate 150 B2B SaaS tenants from legacy infrastructure to a modernized multi-tenant platform. 10M rows across 30+ tables with complex foreign key dependencies. No maintenance windows. Incidents running at 20 per migration cycle.
Architecture approach
- ·Wave-based rollout: 20 progressive waves grouped by size and complexity
- ·FK-safe table ordering via dependency graph analysis
- ·Dual-write strategy during transition with read-from-new after validation
- ·Automated reconciliation: row counts, checksums, business rule validation
- ·Weekend cutover windows with automated rollback scripts and real-time monitoring
Tech stack
Results
- MTTR reduced 30% with wave-based rollout process
- Incidents dropped from 20 to 2
- Zero customer-facing downtime
- All 150 tenants migrated within planned timeline