Rebuilding Index with Compression - SQL Server

Rebuilding Index with Compression is a process in SQL Server that involves rebuilding an existing index on a table with the addition of data compression. This process can help reduce the size of the index, which in turn can help improve query performance and reduce storage costs.

Here is an example of how to rebuild an index with compression in SQL Server:

Assuming we have a table called "SalesData" with an index called "IX_SalesData_SalesDate", which we want to compress.

1) First, we need to identify the index we want to compress:

    SELECT name, type_desc, is_disabled, compression_desc 

    FROM sys.indexes 

    WHERE object_id = OBJECT_ID('SalesData') 

    AND name = 'IX_SalesData_SalesDate';

This query retrieves information about the index, including its name, type, whether it is currently disabled, and its compression settings.

2) Next, we need to rebuild the index with compression:

    ALTER INDEX IX_SalesData_SalesDate 

    ON SalesData(SalesDate) 

    REBUILD WITH (DATA_COMPRESSION = PAGE);

This command rebuilds the index on the "SalesDate" column of the "SalesData" table with PAGE-level data compression. There are three levels of data compression available in SQL Server: NONE, ROW, and PAGE. PAGE-level compression typically provides the best compression ratio with the least impact on query performance.

3) Finally, we can verify that the index has been rebuilt with compression:

    SELECT name, type_desc, is_disabled, compression_desc 

    FROM sys.indexes 

    WHERE object_id = OBJECT_ID('SalesData') 

    AND name = 'IX_SalesData_SalesDate';

This query should now return information about the rebuilt index, including the fact that it is now compressed.