Learn how to efficiently overwrite partitioned table data in Azure Synapse Analytics dedicated SQL pool. Discover the best approach to minimize load times. Essential knowledge for the DP-203 certification exam.
Table of Contents
Question
You have an Azure Synapse Analytics dedicated SQL pool named Pool1. Pool1 contains a partitioned fact table named dbo.Sales and a staging table named stg.Sales that has the matching table and partition definitions.
You need to overwrite the content of the first partition in dbo.Sales with the content of the same partition in stg.Sales. The solution must minimize load times.
What should you do?
A. Insert the data from stg.Sales into dbo.Sales.
B. Switch the first partition from dbo.Sales to stg.Sales.
C. Switch the first partition from stg.Sales to dbo.Sales.
D. Update dbo.Sales from stg.Sales.
Answer
To overwrite the content of the first partition in the dbo.Sales table with the content of the same partition in the stg.Sales table while minimizing load times, the best approach is to use the SWITCH PARTITION command.
The correct answer is: C. Switch the first partition from stg.Sales to dbo.Sales.
Explanation
The SWITCH PARTITION command in Azure Synapse Analytics allows you to efficiently move data between partitions of two tables with matching table and partition definitions. This operation is metadata-only and does not physically move the data, resulting in minimal logging and near-instant execution.
When you switch a partition from the staging table (stg.Sales) to the fact table (dbo.Sales), the data in the specified partition of the fact table is replaced with the data from the corresponding partition in the staging table. This approach is much faster than using INSERT, UPDATE, or DELETE statements to modify the data.
The other options are not optimal for this scenario:
A. Inserting data from stg.Sales into dbo.Sales would duplicate the data instead of overwriting it.
B. Switching the first partition from dbo.Sales to stg.Sales would overwrite the data in the staging table, which is the opposite of what is needed.
D. Updating dbo.Sales from stg.Sales would be inefficient compared to using the SWITCH PARTITION command.
In summary, using the SWITCH PARTITION command to switch the first partition from the staging table to the fact table is the most efficient way to overwrite the content of the specified partition while minimizing load times in Azure Synapse Analytics.
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