Alan is a Data Engineer of Whizlabs Inc who is working on the development of dedicated SQL pool tables for Azure Synapse Analytics for an enterprise data warehouse project.
He's creating statistics for columns of dedicated SQL pool tables as a recommended approach.
He issued the following t-sql statement.
CREATE STATISTICS statistics_column1 on adventureWorks_Sales_1(column1) where column1 > ‘2000101' AND column1 < ‘20001241'What's the purpose of the statement for creating statistics in Synapse analytics dedicated SQL pool tables?
Click on the arrows to vote for the correct answer
A. B. C. D.Correct Answer: D.
The T-SQL statement provided creates statistics for a specific column, column1, in the adventureWorks_Sales_1 table, with a filter on the values of column1 that fall between ‘2000101' and ‘20001241'. The purpose of creating statistics in Synapse Analytics dedicated SQL pool tables is to provide information to the query optimizer about the distribution of data in a column or set of columns. This information helps the query optimizer generate better execution plans by selecting the most efficient algorithms for processing the data.
Option A is not entirely correct. Although statistics are created on a column, the default sample size is not 20%, but rather a dynamic sample size based on the size of the table and other factors.
Option B is not correct. The statement does not specify a sample size, so the default dynamic sample size will be used.
Option C is not correct. The statement creates statistics for a single column, not for multiple columns.
Option D is partially correct. The statement creates statistics for a range of values in column1, but it does not necessarily correspond to the range of values in a partition.
In summary, the purpose of the statement is to create statistics for a column in a Synapse Analytics dedicated SQL pool table, with a filter on a specific range of values in that column. These statistics help the query optimizer generate more efficient execution plans.