Migrating an SQL Server database to AWS RDS Aurora PostgreSQL

 Migrating an SQL Server database to AWS RDS Aurora PostgreSQL 

Step 1: Planning

1. Assess the Migration: Evaluate the source SQL Server database and identify any potential issues. Consider schema differences, data types, and compatibility issues.
2. Backup Strategy: Plan for a backup strategy to ensure you have a point-in-time restore option.
3. Tools and Resources: Familiarize yourself with AWS Database Migration Service (DMS) and AWS Schema Conversion Tool (SCT).

Step 2: Set Up AWS Environment

1. Create an AWS Account: If you don’t already have one, create an AWS account.
2. Set Up IAM Roles and Policies: Ensure you have the necessary IAM roles and policies to manage AWS services securely.
3. Launch Aurora PostgreSQL Instance:
   • Go to the RDS console.
   • Select "Create Database".
   • Choose "Amazon Aurora".
   • Select "PostgreSQL-compatible".
   • Configure the instance size, storage, and other settings.
   • Launch the instance.

Step 3: Schema Conversion

1. Install AWS SCT:
   • Download and install the AWS Schema Conversion Tool from the AWS website.
2. Connect to Source SQL Server:
   • Open AWS SCT.
   • Connect to your SQL Server database by providing the connection details.
3. Connect to Target Aurora PostgreSQL:
   • Connect to your Aurora PostgreSQL instance.
4. Convert the Schema:
   • Use AWS SCT to convert the SQL Server schema to PostgreSQL-compatible schema.
   • Review and apply any necessary modifications manually.
   • Apply the converted schema to the Aurora PostgreSQL instance.

Step 4: Data Migration

1. Install AWS DMS:
   • Go to the AWS DMS console.
   • Create a replication instance.
   • Ensure the replication instance can connect to both the source SQL Server and target Aurora PostgreSQL.
2. Create Endpoints:
   • Create source endpoint for SQL Server.
   • Create target endpoint for Aurora PostgreSQL.
3. Create a Migration Task:
   • Define a migration task in AWS DMS.
   • Choose the type of migration (full load, full load + CDC, or CDC only).
4. Run the Migration Task:
   • Start the migration task.
   • Monitor the migration process using the DMS console.
   • Validate data after the migration task completes.

Step 5: Post-Migration

1. Data Validation:
   • Compare the data in the source SQL Server and target Aurora PostgreSQL to ensure completeness and accuracy.
2. Application Testing:
   • Test your applications with the new Aurora PostgreSQL database to ensure they work as expected.
3. Performance Tuning:
   • Optimize your PostgreSQL database settings for better performance.
   • Apply necessary indexing and query optimizations.

Step 6: Cutover

1. Plan for Downtime:
   • Schedule a maintenance window for the cutover to minimize impact.
2. Final Data Sync:
   • Perform a final data sync if using CDC (Change Data Capture) to ensure no data is missed.
3. Switch Applications:
   • Update your application configurations to point to the new Aurora PostgreSQL database.
4. Monitor:
   • Monitor the applications and database closely after cutover to quickly address any issues.

Step 7: Decommission

1. Decommission Old SQL Server:
   • Once confirmed that the new system is working perfectly, decommission the old SQL Server database.
2. Cleanup:
   • Remove any unused resources in AWS to avoid unnecessary costs.