![]() ![]() In the example below, you can track the update history for the row with AddressID = 16, for all the columns that were changed – AddressLine1 and City. For UPDATE statements, Change Data Capture captures two rows – the row before (_$operation = 3) and the row after (_$operation = 4) the update, so both old and new values are available For INSERT (_$operation = 2) and DELETE (_$operation = 1) statements, Change Data Capture captures the whole row that was inserted/deleted. ChVer is the change version number of the last change, the one that is shownĬhange Data Capture presents more information for each change. The version number is incremented after each change. the version number of the initial change, if there was more than one. The ChCrVer column shows the Change Creation Version, i.e. As shown in the example, Change Tracking shows only that specific columns in the specific row were inserted, updated, or deleted, but it doesn’t show what was inserted, updated, or deleted The AddLine1_Changed and AddLine2_Changed columns indicate whether the specific columns have been changed, 0 shows no changes, otherwise it’s 1. ![]() In this example, the last change is a delete, and that’s the only transaction the Change Tracking feature shows for the rowĪnother important difference mentioned in the feature comparison table above, are the record values captured for each changeĬhange Tracking captures only the primary key of the changed row (the AddressID column in this example) and the change type (shown in the ChOp column – U is update, I -insert, D – delete). Change Data Capture shows 2 transactions – an insert (the row with _$operation = 2) and a delete (_$operation = 1)Ĭhange Tracking shows only the last change for the record. Let’s say a record was inserted and then deleted. The same changes were tracked using both Change Data Capture and Change Tracking. We will show the difference for historical data tracking in an example. Like with Change Tracking, there is a built-in clean-up solution that removes old captured information after a specified timeīoth Change Tracking and Change Data Capture can be enabled on the same database at the same time Change Data Capture vs. For reading the change tables, Change Data Capture provides table-valued functions It captures the information and stores it in tables called change tables. SQL Server Change Data Capture requires no schema changes of the existing tables, no columns for timestamps are added to the tracked (source) tables, and no triggers are created. ![]() If the capture process is not running and there are changes to be gathered, executing CHECKPOINT will not truncate the log.” “Even if the recovery mode is set to simple recovery the log truncation point will not advance until all the changes that are marked for capture have been gathered by the capture process. using triggers)Īs Change Data Capture reads committed transactions from the online transaction log, it uses the transaction commit time, so there are no problems in determining the sequence of long-running and overlapping transactionsĬhange Data Capture is a process that can delay log truncation Database performance is not affected performance overhead is lower than with other solutions (e.g. In Change Data Capture, the information is retrieved by periodic querying of the online transaction log. The mechanism used for capturing and the information captured are different It also captures information about data changes – inserts, deletes and updates, but it provides more details than SQL Server Change Tracking. Same as SQL Server Change Tracking, SQL Server Change Data Capture was introduced in SQL Server 2008 to make the extract, transform, and load processes easier. In this article, we will present another method for tracking SQL Server data changes – SQL Server Change Data Capture SQL Server Change Data Capture If you need to know is whether the row has been changed or not, the type of the last change, and which column was changed, without the details (old and new values, who, and when) about the change, then SQL Server Change Tracking is not the right auditing solution for you We also showed examples of the captured records. In the previous part of this series, How to read SQL Server Change Tracking results, we described SQL Server Change Tracking – its features, how to use it, and how to read the results. ![]()
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