Performance Tuning Guide - EMC Community Network

Designing the Application
The database creates a separate table for each object type used, whether it is an SDT containing many
attributes or a simple process variable containing a single attribute. When searching for attributes
in different database tables, the database dynamically joins rows of database tables in order to
retrieve pertinent data. Joining rows of database tables impacts performance. When using SDTs, a
single database table contains the searchable attributes and avoids the performance impact of the
join operation.
Tip: Use SDTs to consolidate sets of attributes to the minimal number of object types on which your
business process discretely operates.
Figure 11, page 38 illustrates how the database models two simple process variables of different types
(string and int), resulting in two different database tables. Any search against these two process
variables employs multiple unions for each simple process variable, which slows down performance.
In addition, the database cannot create a composite index, which would otherwise provide additional
performance improvements (Creating composite indexes, page 38).
Figure 11. Separate data tables for different process variable types
Model the two process variables (branch and loantype) as attributes of a single SDT, in which case
the database stores all metadata in a single database table (Figure 12, page 38). The database table
can then be searched without the performance overhead of creating unions, as in Figure 11, page
38. In addition, you can create a composite index for SDTs, which provides additional database
performance improvements (Creating composite indexes, page 38).
Figure 12. Single table representation for an SDT
Creating composite indexes
xCP provides developers with the ability to create composite indexes for SDT attribute values.
Creating a composite index can improve database performance, especially when performing complex
(conditional) searches against a large database of different attributes in the same SDT.
38 EMC Documentum xCP 1.0 Performance Tuning Guide