This example registers the DashboardFederationDataSource from the following set of data sources:
- DashboardSqlDataSource (the SQLite database)
- DashboardExcelDataSource
- DashboardObjectDataSource
- DashboardJsonDataSource
The federated data source is stored in the in-memory storage (DataSourceInMemoryStorage) and is available from the Add Data Source dialog. Note that when you add a federated data source to a dashboard, all data sources used in the federated data source are also added to the dashboard.
This example demonstrates the following query types you can use to create a data federation:
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Join
Combines rows from two or more tables based on a clause. The join type specifies records that have matching values in both tables.
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Union and UnionAll
The Union query combines rows from two or more tables into one data set and removes duplicate rows in merged tables. The UnionAll query does the same, except it doesn't remove duplicated rows. You can create a union query for data sources if data types of their columns are implicitly converted.
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Transformation
If a data source contains a complex column (an object), you can transform its properties to display them as separate columns in a flattened view. If one of the data columns is an array, you can unfold its values and display a new data row for every element of the array. When you unfold the column, you can flatten it and create a flattened view