Data migration is a critical activity in enterprise modernization projects.
The right migration strategy impacts migration speed, data quality, and system reliability.
Overview
There are three common approaches to data migration:
- API-Based Migration
- SQL/Data Tool Migration
- Hybrid Migration Approach (Recommended)
1. API-Based Data Migration
API-based migration moves data by communicating with the target application
through APIs instead of writing directly into the database.
Legacy System
|
v
Migration Service
|
v
Target API
|
v
Target Database
Common Tools
- .NET Worker Service
- HttpClient / Refit
- Azure AD OAuth2
- Microsoft.Extensions.Http.Resilience
- Azure Service Bus
- Application Insights
Advantages
- Reuses existing business logic
- Applies application validation rules
- Provides better auditing
- Maintains data integrity
Disadvantages
- Slower for large datasets
- Depends on API availability
- Requires retry and error handling mechanisms
2. SQL/Data Tool Migration
SQL migration transfers data directly between databases using ETL and database tools.
Source Database
|
v
SQL/Data Migration Tool
|
v
Target Database
Common Tools
- Azure Data Factory
- SQL Bulk Copy
- Azure Database Migration Service
- SSIS
- Flyway / Liquibase
Advantages
- Very fast for large data volumes
- Excellent for bulk migration
- Strong transformation capabilities
Disadvantages
- Bypasses application business rules
- Validation must be handled separately
- Higher risk for complex domains
3. Hybrid Migration Approach (Recommended)
The Hybrid Migration Approach combines both SQL migration and API migration.
It uses the fastest approach for simple data while protecting business rules
for complex entities.
Hybrid Architecture
Legacy System
|
--------------------------------
| |
v v
SQL/Data Migration API Migration
Azure Data Factory .NET Worker Service
SQL Bulk Copy REST API
| |
v v
Simple Data Business Data
Lookup Tables Policies
Reference Data Claims
Customers Payments
Historical Data Transactions
|
v
New Application Platform
How Hybrid Migration Works
Step 1: Classify Data
Before migration begins, classify data based on complexity.
Bulk Data Migration
Use SQL/data tools for data that does not require business processing.
- Lookup tables
- Reference data
- Customer master data
- Historical records
Tools:
- Azure Data Factory
- SQL Bulk Copy
Business Data Migration
Use APIs for entities that require validation and workflows.
- Policies
- Claims
- Payments
- Transactions
Tools:
- .NET 10 Worker Service
- REST APIs
Example: Insurance System Migration
| Entity | Migration Method | Tool |
|---|---|---|
| Country | SQL Migration | Azure Data Factory |
| Vehicle Type | SQL Migration | SQL Bulk Copy |
| Customer | SQL Migration | Azure Data Factory |
| Policy | API Migration | .NET Worker + REST API |
| Claim | API Migration | .NET Worker + REST API |
| Payment | API Migration | .NET Worker + REST API |
Enterprise Patterns for Hybrid Migration
Retry Pattern
Use Microsoft.Extensions.Http.Resilience to handle:
- Temporary API failures
- Timeouts
- Network problems
Migration Tracking
MigrationExecution
Entity SourceId Status
Customer 10001 Completed
Policy 20001 Failed
Idempotency
Migration processes should safely retry without creating duplicate records.
First Run:
Policy 10001 Created
Second Run:
Policy 10001 Already Exists
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Comparison
| Feature | API Migration | SQL Migration | Hybrid |
|---|---|---|---|
| Speed | Medium | Excellent | Excellent |
| Business Rules | Excellent | Poor | Excellent |
| Large Data Volume | Poor | Excellent | Excellent |
| Validation | Excellent | Manual | Excellent |
Conclusion
API migration provides safety and business validation.
SQL migration provides speed and efficiency.
For enterprise modernization projects, the Hybrid Migration Approach is usually
the preferred strategy because it combines the performance of SQL tools with
the correctness of application APIs.