Differences between Babelfish for Aurora PostgreSQL and SQL Server

Babelfish is an evolving Aurora PostgreSQL feature, with new functionality added in each release since the initial offering in Aurora PostgreSQL 13.4. It's designed to provide T-SQL semantics on top of PostgreSQL through the T-SQL dialect using the TDS port. Each new version of Babelfish adds features and functions that better align with T-SQL functionality and behavior, as shown in the Supported functionality in Babelfish by version table. For best results when working with Babelfish, we recommend that you understand the differences that currently exist between the T-SQL supported by SQL Server and Babelfish for the latest version. To learn more, see T-SQL differences in Babelfish.

In addition to the differences between T-SQL supported by Babelfish and SQL Server, you might also need to consider interoperability issues between Babelfish and PostgreSQL in the context of the Aurora PostgreSQL DB cluster. As mentioned previously, Babelfish supports T-SQL semantics on top of PostgreSQL through the T-SQL dialect using the TDS port. At the same time, the Babelfish database can also be accessed through the standard PostgreSQL port with PostgreSQL SQL statements. If you're considering using both PostgreSQL and Babelfish functionality in a production deployment, you need to be aware of the potential interoperability issues between schema names, identifiers, permissions, transactional semantics, multiple result sets, default collations, and so on. In simple terms, when PostgreSQL statements or PostgreSQL access occur in the context of Babelfish, interference between PostgreSQL and Babelfish can occur and can potentially affecting syntax, semantics, and compatibility when new versions of Babelfish are released. For complete information and guidance about all the considerations, see the Guidance on Babelfish Interoperability in the Babelfish for PostgreSQL documentation.

Note

Before using both PostgreSQL native functionality and Babelfish functionality in the same application context, we strongly recommend that you consider the issues discussed in the Guidance on Babelfish Interoperability in the Babelfish for PostgreSQL documentation. These interoperability issues (Aurora PostgreSQL and Babelfish) are relevant only if you plan to use the PostgreSQL database instance in the same application context as Babelfish.

Topics

• Babelfish dump and restore
• T-SQL differences in Babelfish
• Transaction Isolation Levels in Babelfish

Babelfish dump and restore

Starting with version 4.0.0 and 3.4.0, Babelfish users can now utilize the dump and restore utilities to backup and restore their databases. For more information, see Babelfish dump and restore. This feature is built on top of PostgreSQL dump and restore utilities. For more information, see pg_dump and see pg_restore. In order to effectively use this feature in Babelfish, you need to use PostgreSQL-based tools that are specifically adapted for Babelfish. The backup and restore feature for Babelfish differs significantly from that of SQL Server. For more information on these differences, see Dump and restore functionality differences : Babelfish and SQL Server. Babelfish for Aurora PostgreSQL provides additional capabilities for backing up and restoring Amazon Aurora PostgreSQL DB clusters. For more information, see Backing up and restoring an Amazon Aurora DB cluster.