03_02.Migration.md

Database Migration Process Overview

Migration

In online (minimal-downtime) migrations, the migration source continues to change. It drifts from the target in terms of data and schema after the one-time migration.
During the Data sync phase, ensure that all changes in the source are captured and applied to the target in near real time. After you verify that all changes are applied, you can cut over from the source to the target environment.

In a delta/incremental migration that uses Azure Data Factory, for each table, use a query that filters (cuts) by date, time, or another parameter. Then finish the migration by using a second query that migrates the remaining data.

• Schema Migration
  • PGAdmin
    • Download
      • Download PGAdmin.
    • Schema Migration
      • You can simply run converted DDL scripts with PGAdmin on Target SQL database.
        
      
      
  • SSMA
    • Schema Migration
      • SSMA Step-by-Step Guide.
      • Hands on Lab Guide for Schema Migration with SSMA.
        
  
  

• Data Migration
  • Initial Migration (One-Time Full Migration)
    • SSMA
      • SSMA Step-by-Step Guide.
      • Hands on Lab Guide for Data Migration with SSMA.
      • Steps to Run SSMA for Oracle
        
    • Azure Data Factory
      • You can use Azure Data Factory for Initial Full Migration from Oracle Database.
        
  • Delta / Incremental Migrtion
    • Azure Data Factory
      • Copy data from Oracle by using Azure Data Factory
      • Incrementally load data from a source data store to a destination data store
      • Delta copy from a database with a control table
      • ForEach Loop to CopyData and Capture Metadata in ControlTable - Part 1
      • ForEach Loop to CopyData and Capture Metadata in ControlTable - Part 2
      • ForEach Loop to CopyData and Capture Metadata in ControlTable - Part 3
  
  

• Useful Tips for Migration

  • Avoid exporting tables with their foreign keys (FKs), constraints, and indexes. These elements slow down the process of importing data into PostgreSQL.
    
  
  

• 3rd Party Solutions for CDC Migration

  • Qlik (Attunity)
  • SQLines
  • Striim

References

• Data Migration Whitepapers
• Oracle to SQL Server Migration Handbook
• SSMA issues and workarounds when migrating Oracle database