A company is planning on hosting their data warehousing solution in Redshift. They are trying to decide on the distribution style for their underlying tables. Which of the following reasons would warrant the use of KEY distribution style for the underlying tables in Redshift.

Answer options:

A.When traffic between nodes needs to be reduced during the join operation
B.When data for the entire table needs to be placed on each node
C.When you need the rows across the node slices in a round-robin fashion
D.When a table does not participate in join

Answer – A
The AWS Documentation mentions the following
The rows are distributed according to the values in one column. The leader node will attempt to place matching values on the same node slice. If you distribute a pair of tables on the joining keys, the leader node collocates the rows on the slices according to the values in the joining columns so that matching values from the common columns are physically stored together.
Option B is incorrect because this belongs to the ALL distribution style
Options C and D are incorrect because this belongs to the Even distribution style
For more information on the distribution styles, please refer to the below URL
https://docs.aws.amazon.com/redshift/latest/dg/c_choosing_dist_sort.html