incorrect grouping

Hi,

while it is correct that Athena is an SQL engine, and Refshift it is a DataBase, they are mostly used in Analytics workloads (ad-hoc queries and analysis) and Data Warehousing and ML (Redshift ML), hence the current classification.

you can also check external sources which define Analytics databases as this one. And you will notice the classification of Presto and Amazon Redshift in this category as well.

hope this helps clarifying.

Amazon Redshift is a fully managed data warehousing service, specifically designed for online analytic processing (OLAP) and business intelligence (BI) applications. This is different from most relational databases that are focussed on row-based transactions (OLTP). The analytics use case means it is grouped with the analytics services.

Amazon Athena is an interactive query service that makes it easy to analyze data in Amazon S3 using standard SQL. Athena does not manage the data, or the S3 objects the data is stored in, so is not classed as a database service.

The key differences between Amazon Redshift and Postgres are described in this doc https://docs.aws.amazon.com/redshift/latest/dg/c_redshift-and-postgres-sql.html

This doc goes into more detail on why columnar storage is important for analytic query performance https://docs.aws.amazon.com/redshift/latest/dg/c_columnar_storage_disk_mem_mgmnt.html