Troubleshooting Error Parsing Array of Strings in Snowflake JSON ARRAY Columns

Discover the solution to fix the "Error parsing JSON" when working with ARRAY data types in Snowflake. Learn how to correctly format your data for seamless CSV imports.
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Troubleshooting Error Parsing Array of Strings in Snowflake JSON ARRAY Columns

When working with Snowflake, you might encounter a perplexing issue while trying to load ARRAY data types from a CSV file. Specifically, the error message "Error parsing JSON" can surface when your data contains something as simple as an array of strings, like ["A","B"]. In this guide, we’ll dive into why this issue occurs and how to effectively resolve it.

Understanding the Issue

The problem arises during the COPY INTO operation from a CSV to a Snowflake table where a column is defined as the ARRAY data type. Suppose we have a column that is expected to receive an array of strings. If the data is formatted incorrectly, such as including extraneous quotes, Snowflake won't parse it as expected.

Example Error

You might run into an error that looks like this when trying to load valid JSON:

[[See Video to Reveal this Text or Code Snippet]]

This suggests that rather than being recognized as a JSON array, the data is being treated as a string. Testing this in the Snowflake console can produce mixed results depending on the format used.

How to Format Your Data Correctly

To solve this problem and ensure that Snowflake correctly interprets the data as an array, you'll need to modify your COPY INTO statement.

Step 1: Adjust Your SQL Statement

Initially, I attempted to use the ARRAY_CONSTRUCT function but found that the CSV column was incorrectly treated as a single string. Instead, we need a method that can parse the string format more effectively.

Solution Using Regular Expressions

While I considered using the REGEXP_SUBSTR_ALL function, it's essential to note that this function is not supported in COPY statements. This realization necessitated a different approach. I recommend using the following SQL query:

[[See Video to Reveal this Text or Code Snippet]]

Breakdown of the Solution

REPLACE(my_col, '"', ''): This operation removes double quotes from the original string to ensure that the JSON array is not misinterpreted.

TRIM(..., '[]'): This function removes any surrounding brackets from the string.

SPLIT(..., ','): Finally, splitting the cleaned string by commas creates an array.

Conclusion

With the correct formatting and functions, you can seamlessly import an array of strings into a JSON ARRAY column in Snowflake without running into parsing errors. By using the SPLIT and REPLACE functions effectively, you can ensure your data imports correctly and efficiently.

If you continue to encounter issues, double-check the formatting of your input data, as even minor discrepancies can lead to parsing failures. Happy querying!