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Question 31 - COF-C02 discussion

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Which of the following indicates that it may be appropriate to use a clustering key for a table? (Select TWO).

A.
The table contains a column that has very low cardinality
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A.
The table contains a column that has very low cardinality
B.
DML statements that are being issued against the table are blocked
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B.
DML statements that are being issued against the table are blocked
C.
The table has a small number of micro-partitions
Answers
C.
The table has a small number of micro-partitions
D.
Queries on the table are running slower than expected
Answers
D.
Queries on the table are running slower than expected
E.
The clustering depth for the table is large
Answers
E.
The clustering depth for the table is large
Suggested answer: D, E

Explanation:

A clustering key in Snowflake is used to co-locate similar data within the same micro-partitions to improve query performance, especially for large tables where data is not naturally ordered or has become fragmented due to extensive DML operations. The appropriate use of a clustering key can lead to improved scan efficiency and better column compression, resulting in faster query execution times.

The indicators that it may be appropriate to use a clustering key for a table include:

D . Queries on the table are running slower than expected: This can happen when the data in the table is not well-clustered, leading to inefficient scans during query execution.

E . The clustering depth for the table is large: A large clustering depth indicates that the table's data is spread across many micro-partitions, which can degrade query performance as more data needs to be scanned.

References:

Snowflake Documentation on Clustering Keys & Clustered Tables

Snowflake Documentation on SYSTEM$CLUSTERING_INFORMATION

Stack Overflow discussion on cluster key selection in Snowflake

asked 23/09/2024
Novka Mandic
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