Columnstore indexes promise to be the savior of every data warehouse. So, what are they, when should you use them, when to stay away? Columnstore indexes are just what they sound like, data physically stored in a columnar way. This is what makes them so fast when it comes aggregating large amounts of data. The data is compressed and similar values are stored together, the database engine can grab all the values it needs to SUM for example, very quickly, this all leads to faster query results.
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