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json_schema.md

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A use case for the json_schema function is to dynamically determine the schema of JSON data stored in a BigQuery table without prior knowledge of its structure. This can be particularly helpful in situations like:

  • Data ingestion from diverse sources: Imagine receiving JSON data from various APIs or partners where the structure might not be consistent or documented thoroughly. json_schema can be used to automatically analyze a sample of the incoming data and infer its schema. This information can then be used to create or validate table schemas, ensuring proper data loading.

  • Data exploration and analysis: When dealing with unfamiliar JSON data, json_schema helps quickly understand its structure and the types of information it contains. This is useful for exploratory data analysis and building queries without manually examining the JSON objects.

  • Schema evolution tracking: By periodically applying json_schema to incoming data, you can detect changes in the JSON structure over time. This allows you to adapt your processing pipelines or table schemas as needed, ensuring compatibility and avoiding errors.

  • Data validation: After inferring the schema, it can be used to validate subsequent JSON data against the expected structure. This can prevent malformed data from being ingested, ensuring data quality.

  • Automated documentation: The output of json_schema can be used to generate documentation for the JSON data, simplifying communication and understanding among different teams or users.

Example Scenario:

Let's say you have a BigQuery table containing a raw_data column storing JSON strings from different sources. You can use the following query to get the schema of the JSON data in each row:

SELECT bigfunctions.us.json_schema(raw_data) AS inferred_schema
FROM your_dataset.your_table;

This will return a table where each row contains the inferred schema of the corresponding JSON data in raw_data. You can then further process this output to:

  • Identify the common schema across different JSON data.
  • Create a new table with the appropriate schema to store the extracted JSON data in a structured format.
  • Flag rows with unexpected schemas for further investigation.

By dynamically determining the schema of JSON data using json_schema, you can make your data ingestion, analysis, and validation processes more robust and efficient.