What is the difference between rowstore and columnstore indexes?

Rowstore indexes organize data by rows and are highly suitable for OLTP patterns such as point lookups, small range queries, and frequent transactional modifications.

Columnstore organizes values by columns, provides high compression, and enables efficient batch-mode processing for large scans and aggregations.

Many systems use both technologies: rowstore for transactional access and columnstore for analytics. The appropriate design depends on read patterns, modification rates, latency requirements, and SQL Server version.