Data Modeling and Management
Objects and relationships
Model data in objects and connect them with relationships. A lookup is a loose link: independent lifecycle, optional on the child, no inheritance of ownership or sharing. A master-detail is a tight link: the child cannot exist without the parent, inherits the parent's owner and sharing, and is cascade-deleted with the parent. Master-detail is what enables rollup summary fields; a lookup has no native rollup. A many-to-many design uses a junction object carrying two master-detail relationships. External IDs let you match records during import and are required for upsert.
Fields and data quality
Know picklists and dependent picklists, record types, validation rules, formula fields, and field history tracking. Formula and rollup fields are calculated at read time and cannot be imported into. Remember that field-level security, page layouts, and record types each solve a different problem; a layout never secures data.
Traps
- Believing a lookup can carry a rollup summary field.
- Forgetting that master-detail children inherit sharing and cannot be reparented unless Allow Reparenting is enabled.
- Attempting to import into a formula field, a rollup field, or via the 15-character ID.
- Using a plain text field where a unique, case-insensitive external ID is needed for upsert matching.
- Expecting children to survive deleting a master-detail parent.
Worked example
Courses and Students is many-to-many: create Course and Student, then an Enrollment junction object with two master-detail fields. Add a rollup on Course counting enrollments, and a unique external ID on Student so nightly imports upsert instead of creating duplicates.