A company stores employee data in Amazon Redshift A table named Employee uses columns named...

In Amazon Redshift, acompound sort keyis designed to optimize the performance of queries that use filtering and join conditions on the columns in the sort key. A compound sort key orders the data based on the first column, followed by the second, and so on. In the scenario given, the compound sort key consists ofRegion ID,Department ID, andRole ID. Therefore, queries that filter on the leading columns of the sort key are more likely to benefit from this order.

Option B: "Select * from Employee where Region ID='North America' and Department ID=20;"This query will perform well because it uses both theRegion IDandDepartment ID, which are the first two columns of the compound sort key. The order of the columns in the WHERE clause matches the order in the sort key, thus allowing the query to scan fewer rows and improve performance.

Option C: "Select * from Employee where Department ID=20 and Region ID='North America';"This query also benefits from the compound sort key because it includesboth Region ID and Department ID, which are the first two columns in the sort key. Although the order in the WHERE clause does not match exactly, Amazon Redshift will still leverage the sort key to reduce the amount of data scanned, improving query speed.

Options A, D, and Eare less optimal because they do not utilize the sort key as effectively:

Option Aonly filters by theRegion ID, which may still use the sort key but does not take full advantage of the compound nature.

Option Duses onlyRole ID, the last column in the compound sort key, which will not benefit much from sorting since it is the third key in the sort order.

Option Efilters onRegion IDandRole IDbut skips theDepartment IDcolumn, making it less efficient for the compound sort key.