Azure Synapse Analytics
An Azure analytics service that brings together data integration, enterprise data warehousing, and big data analytics. Previously known as Azure SQL Data Warehouse.
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Change Feed in Synapse Link for SQL Server 2022 – Getting change data as CSV file without header and starting with 4 meta data columns
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Vignesh K
20
Reputation points
I'm using Azure Synapse Link with SQL Server 2022 (on-premises), and my change data is being stored in ADLS Gen2 as CSV files. I’ve observed that the first four columns in the CSV files contain metadata, but I couldn't find clear documentation explaining their purpose.
I need to:
- Merge the full data Parquet files with the change data CSV files
Convert the merged data into a Delta table
However, I'm unclear on the following:
What do the first four metadata columns in the CSV files represent?
Where can I find the operation type (e.g., insert, update, delete) in the change data?
I've reviewed most of the Microsoft documentation but couldn't find specific information about these metadata columns or how to interpret the operation type.
Azure Synapse Analytics
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J N S S Kasyap 2,610 Reputation points Microsoft External Staff Moderator2025-05-13T11:57:57.23+00:00 Hi @Vignesh K
In Azure Synapse Link for SQL Server 2022, when change data is written to Azure Data Lake Storage Gen2 (ADLS Gen2) as CSV files, each row typically includes four metadata columns followed by the actual data columns from your source SQL Server table. These metadata columns provide essential information about the nature and context of each data change.
These CSV files include four metadata columns at the beginning of each row, which are not explicitly documented in detail in Microsoft’s public documentation but can be inferred based on the behavior of the change feed and related technologies like Change Data Capture (CDC).Appreciate if you could share the feedback on our Provide product feedback.Which would be open for the user community to upvote & comment on. This allows our product teams to effectively prioritize your request against our existing feature backlog and gives insight into the potential impact of implementing the suggested feature.
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J N S S Kasyap 2,610 Reputation points Microsoft External Staff Moderator
2025-05-14T14:48:30.44+00:00 @Vignesh K
We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help. -
Vignesh K 20 Reputation points
2025-05-15T11:53:24.98+00:00 Hey, apologies for the delayed response. Based on my testing so far, it appears that column 2 contains operational details. However, I won't be able to confirm this definitively until I find official documentation from Microsoft.
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