The Process Engine
uses indexes to facilitate and speed up searches. When you create a roster,
queue, or event log, the Process Configuration Console
automatically creates the indexes, marked with a
icon. The indexes that the Process Engine
needs in order to function properly are indicated by the tooltip that appears
when you hold the cursor over the icon. You cannot change or delete a mandatory
system-defined index.
You can define indexes, depending on the needs of your system. You can
add, change, or delete user-defined indexes on rosters, queues, and
event logs.
By default, the Process Engine
creates an index for user queues called PWDefaultOrder. This index determines
the order in which a user's work appears in his Inbox. You can modify this index
to change the default order.
You should use additional indexes sparingly as they add to the system overhead,
both in space and performance. Indexes are the primary means of reducing disk
I/O when properly used. Retrieval performance of indexed data remains almost
constant, even as new rows are inserted. However, the presence of many indexes
on a table decreases the performance of updates, deletes, and inserts because
the system must also update the indexes associated with the table.
You can create simple or composite indexes. A composite index (also called
a concatenated index) is an index that you create on multiple columns
in a table. Columns in a composite index can appear in any order. Composite
indexes can speed retrieval of data for search filters in which the filter
conditions reference all or the leading portion of the columns in the
composite index. Therefore, the order of the columns used in the definition
is important; generally, the most commonly accessed or most selective
columns go first.
If the Properties dialog box is not already displayed, select the icon
of the queue, roster, or event log you wish to modify and click Properties
on the toolbar.
Select the Indexes tab.
Select the user-defined index you wish to change.
Click Edit.
To add fields to the index, select one or more items in the Available
items list and click Add. To remove fields, select one or more items in
the Selected items list and click Remove.
To change the order of the indexed fields, select one or more field names
from the Selected items list, then click
Up or Down.
Click OK when done.
Click Commit Changes
on the toolbar
to apply this change to your isolated region. You can commit the changes immediately,
or you can wait until you have finished all your changes.
NOTE The
commit process suspends all other database transactions within the isolated region
until it finishes. We strongly recommend that you accumulate all changes and commit
them once when you're done, or that you commit changes when the isolated region
is relatively inactive. Avoid committing changes after every modification whenever
possible.
To add an index
If the Properties dialog box is not already displayed, select the icon
of the queue, roster, or event log you wish to modify and click Properties
on the toolbar.
Select the Indexes tab.
Click New.
Enter the name of the index in the Index name
box. The index name must meet the Process Engine
naming requirements.
TIP The
name you enter is a logical name. The Process Engine
dynamically determines the physical table and index names, to prevent collisions
with existing table and index names.
To add fields to the index, select one or more items in the Available
items list and click Add. To remove fields, select one or more items in
the Selected items list and click Remove.
To change the order of the indexed fields, select one or more field names
from the Selected fields list, then click
Up or Down.
Click OK to close the New Index dialog
box.
Click OK when done.
Click Commit Changes
on the toolbar
to apply this change to your isolated region. You can commit the changes immediately,
or you can wait until you have finished all your changes.
To delete an index
If the Properties dialog box is not already displayed, select the icon
of the queue, roster, or event log you wish to modify and click Properties
on the toolbar.
Select the Indexes tab.
Select one or more indexes you wish to delete. You cannot delete mandatory
system-defined indexes, indicated by the tooltip associated with the icon.
Click Delete.
Click Yes or Yes to All to confirm.
Click OK when done.
Click Commit Changes on the toolbar
to apply this change to your isolated region. You can commit the changes immediately,
or you can wait until you have finished all your changes.
NOTESome
system indexes appear with no index key fields defined. The fields actually
indexed are not available for querying, and therefore do not appear in
the list.
NOTE A
roster index must contain the F_WobNum field. If this field is not included
in your indexed fields, it will automatically be added for you when you
close the Index Properties dialog box.