I don't think pointers (beyond a simple "same as in previous row" marker) will be a huge improvement, since you still get a multiplicative number of rows. And it comes with the cost of keeping all that data in memory. This approach also competes with using cheap compression (e.g. LZ4).

Some kind of "product" operator on the other hand reduces the cost to additive (just like `array_agg`).

> That one is tracked here: https://github.com/npgsql/efcore.pg/issues/2633

That issue is only about supporting `array_agg` as a function on tuples, not as an implementation strategy for `Include`s of collections.