Question of the Day

SQL Server Columnstore Index Fragmentation

The columnstore index is absolutely different than the traditional rowstore b-tree index. Because of this, it doesn't suffer from the same kind of fragmentation across pages as the b-tree index. Yet, it does suffer from a type of fragmentation brought about by an excess of deleted rows in a rowgroup and a lack of compression of storage because more things are in the delta store. While b-tree indexes use dm_db_index_physical_stats to show fragmentation, which system tables or DMVs can be used in SQL Server (prior to SQL Server 2025) to determine columnstore fragmentation?