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Jos de Bruijn
2016-05-25 14:23:02 -07:00
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samples/databases/wide-world-importers/wwi-integration-etl/README.md
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@ -39,7 +39,20 @@ To run this sample, you need the following prerequisites.
<a name=run-this-sample></a>
## e
## Running the sample
## Sample details
The ETL package WWI_Integration is used to migrate data from the WideWorldImporters database to the WideWorldImportersDW database as the data changes. The package is run periodically (most commonly daily).
The design of the package uses SSIS to orchestrate bulk T-SQL operations (rather than as separate transformations within SSIS) to ensure high performance.
Dimensions are loaded first, followed by Fact tables. The package can be re-run at any time after a failure.
The workflow is as follows:
It starts with an expression task that works out the appropriate cutoff time. This time is the current time less a few seconds. (This is more robust than requesting data right to the current time). It then truncates any milliseconds from the time.
The main processing starts by populating the Date dimension table. It ensures that all dates for the current year have been populated in the table.
After this, a series of data flow tasks loads each dimension, then each fact.