By default, when you use an EOFetchSpecification, it will fetch all of the EOs that match its EOQualifier. However, often the user interface you will be using is paginated, and there are large performance wins by instead loading your results in pages.
EOFetchSpecification provides a setFetchLimit(int) method, but it does not directly support pagination, rather it will simply stop returning results after the number specified. This is useful for a cut-and-run approach to querying, but if you need to provide multiple pages of results, you will likely need to look elsewhere.
Project Wonder provides several faciliities for addressing this problem:
- ERXEOControlUtilities.objectsInRange(ec, fs, start, end) for PostgreSQL, MySQL, and FrontBase
- ERXFetchSpecificationBatchIterator Max Muller's original post describing this