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Data & Analytics · Advanced

Columnstore Index

A SQL Server and Azure SQL index that stores data column by column in compressed segments for fast analytic scans.

Definition

Clustered columnstore indexes are the default storage for large fact tables in Synapse dedicated SQL pools and are ideal for aggregations over millions of rows. Data is grouped into rowgroups of about one million rows with high compression, and queries use batch-mode execution.

Example

CREATE CLUSTERED COLUMNSTORE INDEX CCI_FactSales ON FactSales;

Exam tip

Rowstore suits OLTP point lookups; columnstore suits analytic scans and aggregations.

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