PRB: Scrolling in Grid May Be Slow with Filtered Cursor

• Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b, 5.0, 5.0a

SYMPTOMS

Scrolling in a grid might be slow if the RecordSource of the grid points to a cursor, which actually is a filter of the table.

RESOLUTION

Use the following steps to work around the problem:

1. Use the SET KEY TO command to filter the data instead of using a SQL SELECT command.

   For example if you wanted to find all the records that have CA for the region field, use the following code:

         SET ORDER TO xregion
         SET KEY TO "CA"
   

   This is assuming that there is a index tag on the region field called "xregion."

2. Use the NOFILTER clause in the SQL STATEMENT to ensure that the cursor created will not be a filter. This clause is only valid in Visual FoxPro 5.0. In Visual FoxPro 3.0 you can add a ".T." to the field list to prevent the filter. For example:

         SELECT *,.t. FROM Customer WHERE country = "USA" INTO CURSOR test
   

STATUS

Microsoft is researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION

This problem occurs only with cursors created with the SQL SELECT command. A local view will not create a filtered cursor.

Steps to Reproduce Behavior

1. Use a large table with more than 200,000 records.

2. Create a simple SQL SELECT statement such as the following:

         SELECT * FROM Customer WHERE country = "USA" INTO CURSOR test
   

3. Create a form with a grid on it.

4. Set the RecordSource property of the grid to the cursor test.

5. Run the form.

6. Drag the scroll button of the grid all the way to the bottom.

(c) Microsoft Corporation 1997, All Rights Reserved. Contributions by David Botzenhart, Microsoft Corporation

Keywords          : FxprgGrid vfoxwin
Version           : Win:3.0,3.0b,5.0,5.0a
Issue type        : kbprb