Clustered columnstore indexes

In the last sections of this chapter, you will learn how to manage a CCI. Besides optimizing query performance, you will also learn how to add a regular B-tree nonclustered index (NCI) to a CCI and use it instead of the primary key or unique constraints. When creating the NCCI in the previous sections, we didn't use LZ77 or archive compression. You will use it with a CCI in this section. Altogether, you will learn how to do the following:

• Create clustered columnstore indexes
• Use archive compression
• Add B-tree NCI to a CCI
• Use B-tree NCI for a constraint
• Update data in a CCI

Compression and query performance

Let's start by dropping both indexes from the demo fact table, the NCCI and the CI, to make a heap again:

USE WideWorldImportersDW; 
-- Drop the NCCI 
DROP INDEX NCCI_FactTest 
  ON dbo.FactTest; 
-- Drop the CI 
DROP INDEX CL_FactTest_DateKey 
  ON dbo.FactTest; 
GO 

Now let's create the CCI:

CREATE CLUSTERED COLUMNSTORE INDEX CCI_FactTest 
  ON dbo.FactTest; 
GO...