sql server cdc

Galaxy Glossary

What is SQL Server Change Data Capture (CDC) and how does it work?

SQL Server Change Data Capture (CDC) is a feature that automatically tracks and logs changes made to specific tables in a database. This allows applications to efficiently retrieve only the updated data, rather than querying the entire table, improving performance and reducing load.

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Description

SQL Server Change Data Capture (CDC) is a powerful tool for tracking changes to data in SQL Server tables. Instead of constantly querying the entire table, CDC provides a dedicated stream of change information. This stream contains details about the changes, including the old and new values of the affected columns. This is crucial for applications that need to react to data modifications in real-time, such as data warehousing, business intelligence, or auditing systems. CDC streamlines the process by providing a dedicated log of changes, eliminating the need for complex triggers or custom solutions. This significantly reduces the overhead of tracking changes, leading to improved performance and scalability. A key benefit of CDC is its ability to capture changes in a way that's independent of the application making the changes. This means that the application doesn't need to be modified to work with CDC, making it a highly flexible solution.

Why sql server cdc is important

CDC is vital for applications needing real-time data updates. It improves performance by only retrieving changed data, reducing the load on the database. It also simplifies the process of tracking changes, making it easier to implement data warehousing and auditing solutions.

Example Usage

```sql -- Enable CDC for the SalesOrderHeader table -- Ensure you have the necessary permissions -- Replace 'yourDatabase' with your database name -- Replace 'SalesOrderHeader' with your table name USE yourDatabase; EXEC sys.sp_cdc_enable_db; EXEC sys.sp_cdc_enable_table @source_schema = N'dbo', @source_name = N'SalesOrderHeader', @role_name = N'YOUR_ROLE', @supports_net_changes = 1; -- Query the CDC data SELECT * FROM cdc.fn_cdc_get_all_changes('dbo.SalesOrderHeader', sys.utcdatetimeoffset('19000101'), sys.utcdatetimeoffset('20240101')); ```

Common Mistakes

Forgetting to enable CDC on the database and table.
Incorrectly specifying the schema and table name in the `sys.sp_cdc_enable_table` procedure.
Using outdated or incorrect syntax for querying the CDC data.
Not understanding the role of the `@supports_net_changes` parameter in `sys.sp_cdc_enable_table`.

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