Editing star schemas
You can edit a star schema according to your needs. Editing options include adding columns, adding attributes and defining filters.
To edit a star schema (fact table):
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Click the Manage button in the bottom left of the Data Mart panel. The Manage Data Marts window opens.
- In the left pane, select the data mart containing the star schema you want to edit.
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Expand the list of start schemas and select the star schema you want to edit. Then either click the Edit button in the lower toolbar or right-click the star schema and select Edit.
The Edit Star Schema - Name window opens. The following tabs are displayed:
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General tab: In the General tab, you can edit the star schema name, the fact table name, the fact view name and the description.
The following option is also available for transactional and aggregated facts:
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Update fact with changes to Type 2 data warehouse entities - Select this option (the default) if you want the fact table to always be updated with the last record version of any Type 2 data warehouse entities the star schema contains.
Example:
Assuming the data warehouse has the following Type 2 entities:
- Orders
- Order Details
- Address
And the data mart consists of the following:
- Fact = Orders and Order Details
- Transaction date = Order Date in Orders
- Dimension = Address (Type 2)
Then the last version of Orders and Order Details will always used and Address will be updated according to the Oder Date.
See also: Data mart views.
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Logical Attributes tab: In the Logical Attributes tab, you can add and delete columns, edit a column’s properties, view a column’s lineage, change the column order, and define filters.
Edit the Logical Attributes tab according to the table below.
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Physical Table tab: The Physical Table tab provides a preview of the actual "physical" columns that will be created in the database. All editing tasks are performed in the Logical Attributes tab, except for defining table creation modifiers which is performed in the Physical Table tab.
For an explanation of how to define table creation modifiers, see Defining Fact Table Creation Modifiers.
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Transaction Date tab: The Transaction Date tab enables you to change the transaction date that you selected when you created the star schema.
For more information on transaction dates, see the Transaction Date screen.
Information noteThis tab will not be displayed if your Star Schema Type is "State Oriented".
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Editing Logical Attributes
To | Do this |
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Edit a column’s properties |
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Delete a column |
Select the column(s) you want to delete (multi-selection is supported) and click the Delete toolbar button. The column(s) are deleted. |
View a Column’s Lineage |
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Create a filter |
Click the Filter toolbar button. The Expression Builder opens with the heading: Edit Filter - TableName. For information on creating filters, see Creating expressions. Information note
Using From Date (FD) and To Date (TD) columns in a filtering expression is not supported. Information note
The assumption is that columns that are used in the filters do not change between different versions of the record. If this is not the case, the Full rebuild option should be selected in the Data Mart settings. This assumption is also true for relationships; for example, if a Sales record relates to Product which relates to Country, and the filter is applied to the product's country, then the assumption is that the sale cannot change its product so that it is filtered in or out based on a new country. |
Create or edit an expression |
Hover the mouse cursor over the desired table column and then click the fx button that appears to the right of the Expression column. The Expression Builder opens with the heading: Edit Expression - Column Name. For information on creating an expression, see Creating expressions. |
Change the column order |
Select the column(s) you want to move and then click the Move Down/Move to Bottom or Move Up/Move to Top buttons as desired. |