Azure Database for PostgreSQL - Hyperscale (Citus) now supports columnar compression with Citus 10. You can use columnar compression with or without the scale-out features of Citus. Postgres typically stores in rows, and row-based tables are good for transactional workloads but can cause excessive IO for some analytical queries. Columnar groups data together by column instead of by row to compress the data as well. Arranging data by column tends to also compress well and means that queries can skip over columns they do not need.
Learn more about columnar compression.