What is a columnstore index? A columnstore index is a technology for storing, retrieving and managing data by using a columnar data format, called a columnstore. columnstore A columnstore is data that is logically organized as a table with rows and columns, and physically stored in a column-wise data format. rowstore A rowstore is data that is logically organized as a table with rows and columns, and then physically stored in a row-wise data format. This has been the traditional way to store relational table data. In SQL Server, rowstore refers to table where the underlying data storage format is a heap, a clustered index, or a memory-optimized table. rowgroup A row group is a group of rows that are compressed into columnstore format at the same time. A rowgroup usually contains the maximum number of rows per rowgroup which is 1,048,576 rows. For high performance and high compression rates, the columnstore index slices the tabl...