As far as I understand,
- prefetchPath is used to defined wich fields should be returned (part of the SELECT portion of the query).
- relations are used to define the filter (part of the JOIN and WHERE clause) but does not imply any returned entities at all (would not load in memory entites imply in the relations if they are not included in the prefetchPath).
I'll have to correct you a little bit on the above:
1- PrefetchPaths don't fetch defined fields as part of the original Select Query.
Rather it fetches each set of related entities in another Select Query.
eg. If you want to fetch a collection of Customers and their related Orders (the Orders related to each customer in the collection).
2 queries will be executed if you use a PrefetchPath to fetch Orders with Customers.
1st Query to fetch Customers.
2nd Query to fetch all Orders related to all the above Customers.
Then LLBLGen Pro associate each set of Oreders to their related specific Customer in the customer.Orders collection.
2- Relations are simply JOINS
3- Predicates are WHERE Clauses (Filters)
4- You may use Relations and Predicates to filter the fecthed Collection.
5- You may also use them to filter a prefetched Collection.
