What is the method for joining a snowflake table using a key that exists in the variant columns?

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To join a snowflake table using a key that exists in the variant columns, you can use the FLATTEN function. The FLATTEN function is used to convert the variant column into separate rows, each containing the value of one of the sub-fields in the variant object.

The general syntax for joining a snowflake table using the FLATTEN function is as follows:

SELECT *
FROM table1 t1
JOIN (
    SELECT t2.key, t2.value.*
    FROM table2 t2, 
         LATERAL FLATTEN(t2.variant_column) 
) t2
ON t1.join_key = t2.key;

In this SQL statement, table1 is the primary table you want to join, table2 is the table with the variant column containing the join key, join_key is the name of the key field in the variant column, and variant_column is the name of the column in table2 that contains the variant object.

The FLATTEN function is used to split the variant object in table2 into separate rows, each containing the key and one value from the subfields. These rows are then joined with table1 using the join key. The .* after t2.value means that all the subfields in the variant object will be returned as separate columns in the result set.

Note that for large tables, this method can be slow and resource-intensive, as the variant column is expanded into multiple rows. Therefore, it is recommended to use this method only when necessary, and when there are no other feasible options for joining tables based on a variant column.