Can anyone explain to me how the "ps_OuterTupleSlot" in PlanState is being used in implementing HashJoin?

Hello there,

 

Can anyone explain to me how the "ps_OuterTupleSlot" in JoinState is being used in implementing HashJoin?

 

 

I looked at the source code. When it find a tuple in outer relation. It store the outer tuple to field   :  node->js.ps.ps_OuterTupleSlot

 

But I can't find how this field is being used in the following processing.

 

 

Thanks,

 

Ran