# Zone Configuration

- DO: Consider limiting the number of rows retrieved by the database limiting the query size. Specify this on the zone parameter and the query will use the rownum technique to restrict the number of rows returned.
- DO: As a rule-of-thumb: 10 columns (even if not visible) in a data explorer zone should be an alert to really think about performance implications.
- DO: Try to perform all processing in the SQL instead of fkInfo, BS, or SS calls in other columns. As described earlier, these would be additional processes run on a per-row basis. If a description exists, consider using the description and a Navigation Option instead of the Foreign Key. For example, replace the Person fkRef with Person Name and its Navigation Option.

Parent topic: Data Explorer