StarRocks, a Linux Foundation project, is a next-generation sub-second MPP OLAP database for full analytics scenarios, including multi-dimensional analytics, real-time analytics, and ad-hoc queries. StarRocks received InfoWorld’s 2023 BOSSIE Award for best open source software.

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*[ Question : Flat Json v2 ]*

Hi, All!

Does the Flat JSON feature also extract common fields from *nested JSON objects*?

In my case, the metadata column contains nested JSON fields, but it seems that Flat JSON is not being applied to those nested values. :thinking_face:

I’d like to confirm whether Flat JSON supports extracting common fields from nested JSON structures, or if it only works for top-level keys.

Based on the documentation, I do not see any explicit limitations regarding nested JSON.

Therefore, I believe that the fields were not extracted due to the default configuration settings, rather than a limitation of nested JSON itself. :thinking_face:

• json_flat_null_factor
• json_flat_sparsity_factor

As you mentioned, I believe, there is no restriction/limitation other than the two settings that you shared, but keep in mind, I think they will increase the storage consumption and loading time.

Thanks for your reply! Flat JSON wasn’t applied because it exceeded the sparsity limit with the default settings, but we did confirm that it works well for commonly occurring nested keys in the JSON object. :slightly_smiling_face:.

So I’m planning to handle the sparse fields using generated columns.