Business Components: VO Tuning
The VO provides tuning parameters that enable you to control SQL execution and how data is fetched from the database. These tuning parameters play a large role in the run-time performance of the VO. If the fetch options are not tuned correctly for the application, your VO may fetch an excessive amount of data and may make too many roundtrips to the database.
For tuning the VO, you can set the following tuning parameters:
Fetch Mode: The default fetch option is the All Rows option, which will be retrieved As Needed (FetchMode="FETCH_AS_NEEDED") or All at Once (FetchMode="FETCH_ALL"), depending on the option you select. The As Needed option ensures that an executeQuery() operation on the VO initially retrieves only as many rows as necessary to fill the first page of a display, whose number of rows is set based on the VO’s range size.
Fetch Size: In conjunction with the Fetch Mode option, the “in Batches of” field controls the number of records fetched at one time from the database (FetchSize in the VO XML). The default value is 1, which gives poor performance unless there is only one row to be fetched. The suggested configuration is to set this value to N+1, where N is the number of rows to be displayed in the user interface.