The Alternate Buffer Pool is a collection of buffers in shared memory that are logically separate from the primary buffer pool. Management of the buffers in the Alternate Buffer Pool is independent of the primary buffer pool. Assigning specific database areas or objects to occupy buffers from the Alternate Buffer Pool might improve your buffer hit rate, thereby reducing the need to read and write buffers to and from disk, and possibly improving performance.
Specifying the best objects for the Alternate Buffer Pool is application-specific. Tables considered "hot" (very active) are good candidates, as are their related indexes. Tables and indexes that are governed by an encryption policy are also considered good candidates because the cost of encrypting and decrypting blocks as they are written and read from disk can be high.
Choose Admin > Alternate Buffer Pool > Alternate Buffer Pool Maintenance to identify objects for the Alternate Buffer Pool. The objects must reside in a Type II area to be individually designated for the Alternate Buffer Pool. Object-level assignments can be made either while the database is online, or while the database is in single-user mode.
Note: Alternate Buffer Pool assignments for SQL objects are made with OpenEdge SQL syntax. For more information, see OpenEdge Data Management: SQL Reference. Alternate Buffer pool assignments for Type I and Type II areas are made with PROUTIL ENABLEB2. For more information, see OpenEdge Data Management: Database Administration.
To select objects for the Alternate Buffer Pool:
1. Choose Admin > Alternate Buffer Pool > Alternate Buffer Pool Maintenance. The Object Selector dialog box appears, as shown:
2. Scroll through the list in the Object Selector dialog box, to select objects, or click Select Some to bring up the Select Objects by Pattern Match dialog box to refine the list. The initial view displays the tables and indexes of the connected database that are currently assigned to the Primary buffer pool.
You can change the list to view objects in the Alternate Buffer Pool by selecting Alternate from the Pool(s) Filter, or you can select both Primary and Alternate. Objects not in the Primary buffer pool have an asterisk before the object type.
3. If you selected too many objects, clicking Deselect Some brings up the Deselect Objects by Pattern Match dialog box, which allows you to enter an object name or pattern you want to deselect.
4. Once you have selected all the objects, click OK to proceed. The Alternate Buffer Pool Maintenance dialog box appears, as shown in the following figure.
Figure 56. Alternate Buffer Pool Maintenance dialog box
5. Select an object, and change the Buffer Pool selection to Alternate. Click Save to make the change, or click Reset to undo the change.
Note: The change is not committed to the database until you click Commit.
6. Once you save a change, the Copy button is activated. Click Copy to propagate your change to multiple objects at once with the Alternate Buffer Pool Maintenance Copy Current Setting To dialog box, shown in the following figure.
Figure 57. Alternate Buffer Pool Maintenance Copy Current Setting To dialog box
7. Continue selecting and modifying object settings until you have specified all the objects you want to change. An asterisk (*) in front of the object name indicates you made changes to that object. Click Review at any time to view the status of your changes.
8. When you complete your changes, click Commit to commit the changes to the database, or click Revert, to cancel all the changes. If you choose to commit your changes, you are asked to confirm your choice.
To remove objects from the Alternate Buffer Pool, follow the same steps as the procedure to select objects for the Alternate Buffer Pool, except in Step <> 5, specify Primary for the Buffer Pool assignment.
