Performance Tuning Guide - EMC Community Network

Designing the Application
For example, if the initial task list page looks for tasks in a queue containing 10,000 tasks, unless the
task list query imposes a limit on the number of results, the database returns all 10,000 results to
Content Server and the application server for task list rendering. The performance impact of this
scenario exposes itself through the following symptoms:
• The initial task list form takes a long time to render when a user clicks the "Tasks" tab in TaskSpace.
• The initial task list displays the tasks, but sorting on a column takes a long time to display the
results.
View the collected DQL query for ENABLE (RETURN_TOP n) hint where n is the number of
fetched rows. Lack of the ENABLE (RETURN_TOP n) hint indicates the following:
• The task list form contains a default sort criteria on a process variable (either primitive or SDT
attribute) and this process variable is not used to filter results (not used in the filter criteria).
Remove the default sort on this process variable from the task list form.
• The task list form displays multiple process variables (either primitive or SDT) and filtering occurs
on a different process variable than sorting. The task list service cannot limit the results from
the database and returns all results to the TaskSpace application server, where the application
server does an in-memory sort. Carefully design the task list form to prevent certain columns
from being sortable.
Avoiding unnecessary preconditions
TaskSpace can be customized using the Documentum Web Development Kit (WDK). One of the most
common TaskSpace customizations affecting performance involves the use of preconditions.
TaskSpace forms that list rows of items (Tasklist, Search, and Folder View, for example), evaluate
preconditions on result sets returned from a database query before displaying each row in the list.
The preconditions evaluate attributes of listed objects to enable or disable actions that the user
can perform on an object (edit or view only, for example). While preconditions provide for rich
functionality, they can have a significant impact on performance.
TaskSpace processes all preconditions for each object in a list before displaying information about that
object as a row on a form. As a result, preconditions exact a multiplicative performance impact on
rendering a complete list in a form. For example, if there are 10 items in a list, each with 20 applicable
preconditions, TaskSpace executes 200 preconditions before rendering the list. A task list that takes 10
seconds to render with preconditions can take 3 seconds to render without preconditions.
Establish a baseline performance metric for your form before adding preconditions. Individually
assess the performance impact of each precondition against the baseline to determine whether the
value offered by the precondition is worth the performance cost.
Note: Many preconditions inspect object attributes such as "object type", "content type", "content
size", "lock owner", and so on. If these attributes are not present in the search query of the form,
TaskSpace performs a full fetch of the object to retrieve the attributes, which adds an additional
performance impact.
50 EMC Documentum xCP 1.0 Performance Tuning Guide