Campaign - Opportunities in Campaign field

Question

Silly question but I have researched the Campaign Fields with no luck for my answer. I was looking at the Campaign, the field Opportunities in Campaign(NumberOfOpportunities) I expected this to be a rollup summary because it shows how many opportunity are related to the Campaign however the field states that it is just a number(9,0). Is this something that salesforce does through Apex that I cannot see?

I am researching this because I have a hierarchy in which the parent Campaign doesn't show the total number of its child's opportunity's.....

Any input is appreciated.

Answer 1

From the Doc:

Calculated field for number of opportunities associated with the campaign. (Read only)

Salesforce automatically calculates this amount using all associated records regardless of whether you have read access to them. This field cannot be referenced in formulas for workflow rules, validation rules, field updates, or approval processes, but it can be referenced in custom formula fields. Updates to this field do not trigger workflow rules.

Answer 2

NumberOfOpportunities is a bit of a magic field, as are all of the other summary fields on Campaigns. It behaves like a rollup field, but the calculations are asynchronous, and delayed by up to 10 minutes. Note that this field only shows Opportunities directly related to this Campaign (i.e. the Primary Campaign field on the Opportunity refers to that Campaign). If you want to see the total summary of all Opportunities attached to all child Campaigns, look at the HierarchyNumberOfOpportunities field instead.