What does the LATERAL modifier for the FLATTEN function do?

The correct answer is C. Joins information outside the object with the flattened data. When FLATTEN is used with the LATERAL modifier in Snowflake, it creates a lateral join between the flattened output and the outer query row. This means that for each row in the outer table, FLATTEN is applied and its results are joined back to that row's other columns. Without…

Data Transformations

Question

Options

ACasts the values of the flattened data
BExtracts the path of the flattened data
CJoins information outside the object with the flattened data
DRetrieves a single instance of a repeating element in the flattened data

How the community answered

(19 responses)

A
5% (1)
B
5% (1)
C
89% (17)

Explanation

When FLATTEN is used with the LATERAL modifier in Snowflake, it creates a lateral join between the flattened output and the outer query row. This means that for each row in the outer table, FLATTEN is applied and its results are joined back to that row's other columns. Without LATERAL, the flattened data would be isolated and you could not reference columns from the enclosing table. In practice, LATERAL FLATTEN is the standard pattern for unpacking arrays or objects within a column while keeping access to the rest of the row's data. It does not cast values (A), extract paths as a primary purpose (B), or retrieve single instances of repeating elements (D - that would describe a different operation like GET or array indexing).

Topics

#FLATTEN function#LATERAL modifier#Semi-structured data#Data transformation

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