Thx, Stamatis, that somehow make sense, if i pass around the parent node every time I visit a RelNode and keep the parents in the cache, but it is still not that intuitive. Actually I what a to add a new RelTrait which bind to a specific scope, for example:
join-rel(trait1) / \ join2 join3 Join-rel has a trait trait1, and I want all the children of join-rel can see this trait, with Calcite’s default metadata handler, I can only see the trait from children nodes(traits propagate from the inputs), and I have no idea how to propagate a trait reversely? Best, Danny Chan 在 2019年4月22日 +0800 PM8:44，Stamatis Zampetakis <[email protected]>，写道： > Hi Danny, > > Apart from RelShuttle there is also RelVisitor which has a visit method > that provides the parent [1]. Not sure, if it suits your needs. > > Best, > Stamatis > > [1] > https://github.com/apache/calcite/blob/ee83efd360793ef4201f4cdfc2af8d837b76ca69/core/src/main/java/org/apache/calcite/rel/RelVisitor.java#L43 > > > On Mon, Apr 22, 2019 at 2:14 PM Yuzhao Chen <[email protected]> wrote: > > > Now for RelNode, we have method getInput()[1] to fetch the input > > RelNodes, but how we fetch the parent ? > > > > For example, we have plan: > > > > join-rel > > / \ > > scan1 scan2 > > > > > > We can get scan1 and scan2 in join-rel directly with method getInput, but > > how can we get the join rel in scan1 and scan 2 ? > > > > I know that there is a RelShuttle that can visit every RelNode and if I > > make a cache for the inputs mapping, finally I can get the ‘parents’ from > > the cache, but this is boring code and not that intuitive. > > > > Do you guys have any good ideas ? > > > > [1] > > https://github.com/apache/calcite/blob/ee83efd360793ef4201f4cdfc2af8d837b76ca69/core/src/main/java/org/apache/calcite/rel/RelNode.java#L132 > > > > > > Best, > > Danny Chan > >
