On Tue, Dec 18, 2007 at 02:48:23PM +0100, [EMAIL PROTECTED] wrote: > But then, I still don't get the relationship between > > INNER, OUTER varnos on the one side and > ecxt_scantuple, ecxt_outertuple and ecxt_innertuple on the other side. > > May a non-leaf node refer to a Var with a 'normal' scan varno or only to > INNER and OUTER varnos?
They're just variables. When you call a subnode it returns a tupletableslot. When you want to return a tuple to your parent, you just return it. > How is my Foo node supposed to access the suplan's (whatever that > might me, a Scan or a Join) columns? Should Foo'- tlist have Vars > with OUTER varnos and the right varattos? You call your subplan: mysubplantuple = ExecProcNode(mysubplan). Vars and VarNos are just if you want to use ExecProject (which is not required). > I cannot find an example of a node that (1) does projection and (2) > is not a Scan (i.e a leaf node) and (3) uses ecxt_scantuple to pipe > information to an upper node. You don't use ecxt_scantuple to pipe to your parent, you create a new tuple based on the old ones, and simply "return" it. You don't have to use the ecxt_* fields at all, for example, the ExecAppend node. It's just convenient to reuse fields that are used for a common purpose. Have a nice day, -- Martijn van Oosterhout <[EMAIL PROTECTED]> http://svana.org/kleptog/ > Those who make peaceful revolution impossible will make violent revolution > inevitable. > -- John F Kennedy
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