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Create Polling Query Dialog Box (SSAS)

  • Artykuł

Use the Create Polling Query dialog box in Business Intelligence Development Studio to create a polling query in the Notifications tab of the Storage Options dialog box. A polling query is typically a singleton query that returns a value Analysis Services can use to determine if changes have been made to a table or other relational object. You can display the Create Polling Query dialog box by clicking the ellipsis button (...) on the Polling Query column of the grid for the Scheduled polling option on the Notifications tab of the Storage Options dialog box. For more information about the Notifications tab of the Storage Options dialog box, see Notifications (Storage Options Dialog Box) (SSAS).

The type of value that should be returned by the polling query depends on the type of updates planned for the multidimensional OLAP (MOLAP) cache of the object based on the table being queried:

  • If Enable incremental update is not selected on the Notifications tab of the Storage Options dialog box, Analysis Services fully updates the MOLAP cache for the object if a change is detected during scheduled polling. The polling query used should determine if records have been added to the table since the last polling period.
  • If Enable incremental update is selected on the Notifications tab of the Storage Options dialog box, Analysis Services incrementally updates the MOLAP cache for the object if a change is detected during scheduled polling. The polling query used should determine the last record in the table.

For example, you can use the following polling queries to supply either full or incremental updates for the Customer dimension in the Adventure Works DW sample Analysis Services database:

Update type Polling query

Full update

SELECT

COUNT(*) AS TotalCount

FROM

[dbo].[DimCustomer]

Incremental update

SELECT

MAX([CustomerKey]) AS LastCustomerKey

FROM

[dbo].[DimCustomer]

For more information about full and incremental updates for scheduled polling notifications, see Proactive Caching.

The query entered must be a valid query command for the underlying provider. The query is prepared with the underlying provider for validation, and to identify the columns returned. The dialog box can present two views:

  • Visual Database Tools (VDT) Query Builder
    For all users, the VDT Query Builder view provides a set of user interface tools for visually constructing and testing a SQL query.
  • Generic Query Builder
    For advanced users, the Generic Query Builder view provides a simpler, more direct user interface for constructing and testing a SQL query.

Options

  • Data Source
    Specifies the data source for the query.
  • Query definition
    The query definition provides a toolbar and panes in which to define and test the query, depending on the selected view.

  • Toolbar
    Use the toolbar to manage datasets, select panes to display, and control various query functions.

    Value

  • Diagram pane
    Displays the objects referenced by the query as a diagram. The diagram shows the tables included in the query, and how they are joined. Select or clear the check box next to a column in a table to add or remove it from the query output.

    When you add tables to the query, the dialog box creates joins between tables based on the keys in the table. To add a join, drag a field from one table onto a field in another table. To manage a join, right-click the join.

    Right-click the Diagram pane to add or remove tables, select all the tables, and show or hide panes.

    Note

    The contents of the Diagram pane, Grid pane, and SQL pane are synchronized, so that changes in one pane are reflected in the other two panes.

    Important

    Changing query types is not supported by the dialog box.

  • Grid pane
    Displays the objects referenced by the query in a grid. You can use this pane to add and remove columns to the query and change the settings for each column.

    Note

    The contents of the Diagram pane, Grid pane, and SQL pane are synchronized, so that changes in one pane are reflected in the other two panes.

  • SQL pane
    Displays the query as a SQL statement. Type to change the SQL statement for the query.

    Note

    The contents of the Diagram pane, Grid pane, and SQL pane are synchronized, so that changes in one pane are reflected in the other two panes.

  • Result pane
    Displays the results of the query when you click Run on the Toolbar pane.

See Also

Reference

Analysis Services Designers and Dialog Boxes (SSAS)

Help and Information

Getting SQL Server 2005 Assistance