Postgres Pro
Downloads
Home   >   mailing lists

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

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

From
Ran Tang
Date:
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

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

From
Tom Lane
Date:
Ran Tang <8rt4@queensu.ca> writes:
> Can anyone explain to me how the "ps_OuterTupleSlot" in JoinState is being used in implementing HashJoin?

Hmm ... [ sounds of grepping ]  actually it looks to me like
PlanState.ps_OuterTupleSlot is entirely dead code now.  The thing that
actually does something useful is econtext->ecxt_outertuple, which feeds
into qual-condition-checking and result-tuple-projection via Vars that
have varno=OUTER.  But I don't see anyplace that is using the
ps_OuterTupleSlot field.
        regards, tom lane