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Question 93 - DEA-C01 discussion

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Michael, a Data Engineer Running a Data query to achieve Union of Data sets coming from Multi-ple data sources, later he figured out that Data processing query is taking more time than expected. He started analyzing the Query performance using query profile interface. He discovered & realized that he used UNION when the UNION ALL semantics was sufficient.

Which Extra Data Processing Operator Michael figured out while doing query profile analysis in this case which helps him to identify this performance bottlenecks?

A.
Aggregate
Answers
A.
Aggregate
B.
UNION ALL
Answers
B.
UNION ALL
C.
Flatten
Answers
C.
Flatten
D.
Join
Answers
D.
Join
E.
Filter
Answers
E.
Filter
Suggested answer: A

Explanation:

In SQL, it is possible to combine two sets of data with either UNION or UNION ALL constructs. The difference between them is that UNION ALL simply concatenates inputs, while UNION does the same, but also performs duplicate elimination.

A common mistake is to use UNION when the UNION ALL semantics are sufficient. These que-ries show in Query Profile as a UnionAll operator with an extra Aggregate operator on top (which performs duplicate elimination).

To Know more about Data Processing Operators, please do refer:

https://docs.snowflake.com/en/user-guide/ui-query-profile#operator-types

asked 23/09/2024
Tuukka Valkeasuo
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