qqq

From Legacy Systems

Migrate legacy systems to qqq

Migrating Legacy Systems

Strategies for migrating legacy applications to qqq.

Assessment

Before migrating, assess:

  • Data Model - Document existing tables and relationships
  • Business Logic - Identify processes and workflows
  • Integrations - List external system connections
  • Users - Understand user roles and permissions

    • Migration Strategies

    Strangler Fig Pattern

    Gradually replace legacy components:

    1. Identify Boundaries - Find natural seams in the system

    2. Build New - Create qqq version of one component

    3. Redirect Traffic - Route requests to new component

    4. Retire Old - Remove legacy component

    5. Repeat - Continue with next component

    Big Bang Migration

    Replace entire system at once:

  • Higher risk, faster completion
  • Requires comprehensive testing
  • Best for smaller systems

    • Parallel Running

    Run both systems simultaneously:

    1. Build qqq application

    2. Sync data between systems

    3. Validate outputs match

    4. Switch users to new system

    5. Decommission legacy

    Data Migration

    Schema Mapping

    Map legacy schema to qqq tables:

    Legacyqqq
    CUST_TBLcustomer
    ORD_HEADERorder
    ORD_DETAILorderLineItem

    Data Import

    Use qqq's import capabilities:

    Bash
    qctl import --table customer --file customers.csv

    Data Validation

    Verify migrated data:

  • Record counts
  • Relationship integrity
  • Business rule validation

    • Common Challenges

  • Undocumented Logic - Hidden rules in legacy code
  • Data Quality - Cleaning during migration
  • User Training - New interface adoption
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