Recommended process to migrate an existing rds postgres db to aurora dsql

Based on the available information, there isn't specific documentation about migrating directly to Aurora DSQL from RDS PostgreSQL or Aurora PostgreSQL. However, I can outline the general migration approaches that are available for PostgreSQL migrations to Aurora PostgreSQL, which may be applicable:

For homogeneous PostgreSQL migrations, you typically have three main approaches:

1. Using native PostgreSQL tools like pg_dump and pg_restore for full load migrations. This would involve taking your database offline, as you suggested.

2. Using AWS Database Migration Service (AWS DMS) for both full load and ongoing replication, which can help minimize downtime.

3. Using a hybrid approach that combines native tools for full load and AWS DMS for ongoing replication.

For migrating from RDS PostgreSQL to Aurora PostgreSQL specifically, you would normally have these options:

• Migrating using an RDS snapshot
• Creating an Aurora read replica of your RDS PostgreSQL instance
• Using AWS DMS
• Importing data from Amazon S3

Since Aurora DSQL is relatively new, it's possible that not all these migration paths are currently supported. Without specific documentation for Aurora DSQL migrations, using pg_dump and pg_restore might indeed be the most reliable approach currently available, though it would require downtime.

I would recommend contacting AWS Support for the most up-to-date guidance on Aurora DSQL migration options and any roadmap for additional migration methods that might be coming soon.
Sources
Planning your database migration process - Migrating Your Databases to Amazon Aurora
Migrating PostgreSQL Databases to Amazon RDS for PostgreSQL or Amazon Aurora PostgreSQL - Database Migration Guide
Migrating data to Amazon Aurora with PostgreSQL compatibility - Amazon Aurora
Migrate or upgrade your like-to-like databases using AWS DMS homogeneous migration | AWS Database Blog