Merge pull request #1639 from SoftwareAG/feature/DataHub-Addtl-Cols-e…

…xploration

Feature/data hub addtl cols exploration

content/datahub/working-with-datahub-bundle/configuring-offloading-jobs.md

@@ -98,13 +98,11 @@ If you enter the additional result columns step for an active offloading pipelin
 
 **Add an additional result column**
 
-When adding an additional result column, a dialog box for defining the column opens. You must define a unique column name as well as a source definition. You can validate the source definition and preview its results by clicking **Validate and preview**.
-
-Regarding the source definition, the first step is to specify a field from the base collection in the source definition editor. Then you can optionally apply SQL functions to adapt the data of this field to your needs, for example, by trimming whitespace or rounding decimal values. The source definition editor supports you in this process with content completion and syntax highlighting. The **Change data type** controls helps you to define a function which changes the data type of the source definition. For example, the source definition is of type VARCHAR and corresponding values are always either true or false. Then you can select Boolean in the **Change data type** dropdown box to define a function which casts the VARCHAR values to BOOLEAN. Different target data types are available in the control, with some of them having options for dealing with non-matching values. For example, if you want to cast all values to type INTEGER and the non-matching literal N/A is processed, you can configure the casting function to use value 0 instead. If you have selected a data type you want to change to, click **Apply** to apply or **Cancel** to revert that type change. Note that functions you can apply to the source definition are not limited to the data type change functions provided under **Change data type**. In the source definition editor you can apply all SQL functions supported by Dremio, as listed under [SQL Function Categories](https://docs.dremio.com/software/sql-reference/sql-functions/).
+When adding an additional result column, a dialog box for defining the column opens. You must define a unique column name as well as a source definition. Regarding the source definition, the first step is to specify a field from the base collection in the source definition editor. Then you can optionally apply SQL functions to adapt the data of this field to your needs, for example, by trimming whitespace or rounding decimal values. The source definition editor supports you in this process with content completion and syntax highlighting. The **Change data type** controls helps you to define a function which changes the data type of the source definition. For example, the source definition is of type VARCHAR and corresponding values are always either true or false. Then you can select Boolean in the **Change data type** dropdown box to define a function which casts the VARCHAR values to BOOLEAN. Different target data types are available in the control, with some of them having options for dealing with non-matching values. For example, if you want to cast all values to type INTEGER and the non-matching literal N/A is processed, you can configure the casting function to use value 0 instead. If you have selected a data type you want to change to, click **Apply** to apply or **Cancel** to revert that type change. Note that functions you can apply to the source definition are not limited to the data type change functions provided under **Change data type**. In the source definition editor you can apply all SQL functions supported by Dremio, as listed under [SQL Function Categories](https://docs.dremio.com/software/sql-reference/sql-functions/).
 
 If you want to derive additional result columns from nested content, you can specify the nested fields using the prefix "src." and the path to the nested field. For example, if you have a top-level field "someField" with a nested field "someSubField", add "src.someField.someSubField" as additional result column. In the same way you can access nested arrays. If you have a top-level field "someField" with a nested array field "someArraySubField", add "src.someField.someArraySubField[0]" as additional result column to access the first array entry.
 
-<img src="/images/datahub-guide/datahub-add-addtl-col.png" alt="Add additional result column" style="max-width: 100%">
+To validate the source definition and preview its results click **Load samples**. The system retrieves data of the associated collection, per default from the last 24 hours, and evaluates the source definition against that data. Results being **NULL** are filtered out. The maximum number of results is limited to 100. You can adjust the timeframe from which data is sampled using the time controls at the right top. The timeframe covers at maximum the last seven days. To search for specific sample values, filter the current list of sample results with the filter controls at the top. The type of the sample results depends on the source data and the source definition. For complex types like **STRUCT** browse through the nested content of a sample entry by clicking at the nodes within the entry. If you want to set the source definition to a specific path of an entry, navigate to that path and click the hand icon right next to the path. You can also copy the path using the copy icon next to the path. Once you modify the source definition, the current sample results typically do not match anymore. Click **Reload** to retrieve a list of sample results with respect to the new source definition.
 
 Click **Save** to add the column, which will be selected for offloading by default. If the source definition is invalid, for example when accessing an unknown column, you get an error message like *Column "UnknownColumn" not found in any table*. You must fix the source definition before you can proceed. Click **Cancel** to cancel the configuration of the additional result column.