The primary requirement is to migrate a Microsoft SQL Server database to AWS while optimizing costs. Babelfish for Aurora PostgreSQL is a capability of Amazon Aurora PostgreSQL-Compatible Edition that allows it to understand the SQL Server wire protocol (TDS) and T-SQL dialect. This enables migration from SQL Server to the cost-effective, open-source-compatible Aurora PostgreSQL engine with minimal to no application code changes. By moving away from the commercial SQL Server engine, the company eliminates expensive licensing fees, which is the most significant factor in cost optimization for this scenario. Aurora's managed nature also reduces operational overhead compared to self-managed solutions.

A. Migrating to SQL Server on EC2 still requires paying for Microsoft SQL Server licenses and adds the operational burden of managing the instance, making it less cost-optimized.

C. A direct migration to PostgreSQL on EC2 would require significant, costly application refactoring and schema conversion, and lacks the benefits of a managed database service.

D. Amazon RDS for Microsoft SQL Server is a managed service but still incurs licensing costs for the commercial SQL Server engine, failing to meet the primary goal of cost optimization.

1. AWS Documentation

"Working with Babelfish for Aurora PostgreSQL": In the section "What is Babelfish for Aurora PostgreSQL?"

it states

"With Babelfish

Aurora PostgreSQL now understands T-SQL

Microsoft SQL Server's proprietary SQL dialect

and supports the same communications protocol

so your apps that were originally written for SQL Server can now work with Aurora with fewer code changes." This confirms its suitability for migrating SQL Server applications.

2. AWS Documentation

"Migrating a SQL Server database to Babelfish for Aurora PostgreSQL": The overview section of this guide highlights the benefits

which include "Stop paying for expensive and restrictive database licenses." This directly addresses the cost optimization requirement of the question.

3. AWS Database Blog

"Modernize Microsoft SQL Server to Amazon Aurora with Babelfish": This article explains the value proposition: "Babelfish for Aurora PostgreSQL reduces the risk of migration projects by reducing the amount of code you have to change... It also helps you stop paying for expensive database licenses." This reinforces that Babelfish is the optimal path for cost-effective SQL Server modernization.

4. AWS Documentation

"Amazon Aurora Pricing": This page details the pricing for Aurora

which does not include commercial license fees

unlike RDS for SQL Server. It highlights cost-effectiveness through features like I/O-Optimized configurations and pay-per-use models

contrasting with the fixed licensing costs of commercial databases.