How to parse a JSON formatted string in Azure SQL Data Warehouse?

Question

T-SQL has a couple of functions that can parse JSON data, but none of them are applicable to Azure SQL Data Warehouse.

I have data in JSON format in a VARCHAR column that looks like:

{'Purpose': 'Purpose 1', 'Activity': 'This activity'}

I could extract the 'Purpose' field in SQL Server by using the JSON_VALUE function:

SELECT JSON_VALUE('{'Purpose': 'Purpose 1', 'Activity': 'This activity'}', '$.Purpose');

But this is not supported in SQL Data Warehouse. Is there a way to do this in SQL Data Warehouse?

https://docs.microsoft.com/en-us/sql/t-sql/functions/json-functions-transact-sql

Answer 1

Update June 2019: This feature is in preview as at end of May 2019:

https://azure.microsoft.com/en-us/blog/azure-sql-data-warehouse-releases-new-capabilities-for-performance-and-security/

You should still consider if this is appropriate to do in your expensive Azure SQL Data Warehouse.

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No. Do this kind of processing in Azure SQL Database which does actually support JSON processing. Start here:

Getting started with JSON features in Azure SQL Database

https://docs.microsoft.com/en-us/azure/sql-database/sql-database-json-features

You should also read this SQL Data Warehouse patterns and anti-patterns article. Consider if your expensive MPP is the right place for this type of processing: https://blogs.msdn.microsoft.com/sqlcat/2017/09/05/azure-sql-data-warehouse-workload-patterns-and-anti-patterns/