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.
Click on the arrows to vote for the correct answer
A. B. C. D.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.htmlThe distribution style for a table in Amazon Redshift determines how the data in the table is distributed across the nodes in the Redshift cluster. The distribution style you choose can have a significant impact on the performance of your queries. In this case, the company is trying to decide whether to use the KEY distribution style for their underlying tables in Redshift, and they want to know what reasons would warrant this decision.
The KEY distribution style in Redshift distributes the data based on the values in one column, which is defined as the distribution key. The rows with the same distribution key value are stored on the same node in the Redshift cluster. This distribution style is ideal for tables that are frequently joined on a specific column, as it reduces the amount of traffic between nodes during the join operation.
Therefore, the correct answer to the question is A. When traffic between nodes needs to be reduced during the join operation.
Option B is incorrect because the ALL distribution style is the one that places the entire table on each node. However, this distribution style is not recommended for large tables as it can lead to performance issues.
Option C is incorrect because the ROUND ROBIN distribution style distributes the rows across the node slices in a round-robin fashion. This distribution style is useful when you want to distribute the rows evenly across all the nodes in the cluster, but it does not help with join operations.
Option D is incorrect because any table can participate in a join operation, regardless of the distribution style.
In conclusion, the KEY distribution style is useful for tables that are frequently joined on a specific column, as it reduces the amount of traffic between nodes during the join operation.