You are designing an Azure SQL Data Warehouse. You plan to load millions of rows of data into the data warehouse each day.

You must ensure that staging tables are optimized for data loading.

You need to design the staging tables.

What type of tables should you recommend?

A. Round-robin distributed table

B. Hash-distributed table
C. Replicated table
D. External table

Explanation:
To achieve the fastest loading speed for moving data into a data warehouse table, load data into a staging table. Define the staging table as a heap and use round-robin for the distribution option.

Incorrect:
Not B: Consider that loading is usually a two-step process in which you first load to a staging table and then insert the data into a production data warehouse table. If the production table uses a hash distribution, the total time to load and insert might be faster if you define the staging table with the hash distribution. Loading to the staging table takes longer, but the second step of inserting the rows to the production table does not incur data movement across the distributions.

References:
https://docs.microsoft.com/en-us/azure/sql-data-warehouse/guidance-for-loading-data