Checklist for Data Migration

Important initial questions 5
  Planning 5
  Are the Data “Clean” ? 5
    Data Model Design Errors 5
    Data Integrity 5
    Character set-Problems 7
  Data 9
    Data Redundancy 9
    Non-Trivial Data Types 9
  Archived Data 10
  Environments for Production and Testing 10
  Other Pitfalls 11
    "Empty" Character-Strings 11
Methods of data transformation 12
  Create-Table-As-Select (CTAS) via DB-Link versus extraction to file 12
  Extraction to File 13
  Transfer of Data (Files) 14
  Loading of Data 14
Space Considerations 15
Change in Size of Data 15
  Redolog/Archivelog  / Transaction log 16
  Rollback Segments 17
Minimizing Downtime / Outage Window 19
  Reduce the amount of data to be migrated during the outage window 19
    Migrate historic data already before outage 19
    Archiving everything possible to be archived 19
    Migrate all other static data before outage 19
  Increase Performance 19
    Extract and load different tables at the same time 19
    Optimizing Index Creation 20
    Optimizing Creating Statistics 21
Migration Steps 22
Back-out Plan 23
  Problems during migration before final tests 23
  Successful Migration, all final tests passed but problems after starting operations on new system 23
Checks after Migration / initial Loading 24