Performance Tuning Guide - EMC Community Network

Designing the Application
Figure 18. Interface for manually defining search queries
Note: Wildcards (SELECT *) are not supported in manual queries.
Follow the same performance-related guidelines in your advanced (manual) queries that are followed
for simple queries, including minimizing the number of attributes searched and setting appropriate
results restrictions.
Restricting advanced search results
Avoid designing search templates that do not restrict result sets. In the following example:
SELECT r_object_id, object_name, commodity_code, commodity_description
FROM e2e_commodity WHERE commodity_code LIKE '%$SEARCH_CODE$%'
the query provides placeholder variable (%$SEARCH_CODE$%) which the end user specifies at run
time. If the query returns 10,000 results, all 10,000 results get returned to the TaskSpace application
server after a single user click. The large number of results can result in poor performance for the
user performing the search and the overall TaskSpace application.
To improve single user and overall TaskSpace performance, restrict query result sets by adding
ENABLE (RETURN_TOP n) to the DQL query.
SELECT r_object_id, object_name, commodity_code, commodity_description
FROM e2e_commodity WHERE commodity_code LIKE '%$SEARCH_CODE$%' ENABLE (RETURN_TOP 501)
The ENABLE (RETURN_TOP 501) restricts the query results to the first 501 rows that match the
search criteria, even though there are many more possible matches.
46 EMC Documentum xCP 1.0 Performance Tuning Guide