Re: How to traverse RelNode’s parent conviniently?

This is a very interesting topic, thanks for starting this discussion Danny! Metadata seems a very reasonable way to handle hints and I guess the proposal by Julian is the way to go. For the sake of discussion (brainstorming), I was thinking that rules from hints do not differ too much. The

Re: How to traverse RelNode’s parent conviniently?

Thx Julian Mostly got your idea, but one thing needs to confirm: Now the MetadataHandler is kind of query lazy the cache is code-gen ed in the handler class, the metadata also propagate from inputs, when I got an RelNode’s hint, how can I cache it in the metadata handler for querying ? Best,

Re: How to traverse RelNode’s parent conviniently?

The RelMetadata system is designed for these kinds of annotations - if there is a “global hints cache” there’s no benefit to doing it outside the RelMetadata system. That said, I don’t know (and I don’t think anyone knows) how we want hints to be propagated as we generate RelNodes from

Re: How to traverse RelNode’s parent conviniently?

Thx, Julian Let me repeat my thoughts about the details again, in order to implement the hints, maybe these things are needed: The main diff is that we will maintain a global hints cache 1. Supports hints grammar for parser.jj 2. During/after sql-to-rel, we may pass a hints cache to the

Re: How to traverse RelNode’s parent conviniently?

I think it’s OK to attach hints to the (few) RelNodes that come out of the SqlToRelConverter. But it would be a mistake to try to propagate those hints to all of the RelNodes that are created during query planning. Even if we changed all of the copy methods (a huge task) there are many other

Re: How to traverse RelNode’s parent conviniently?

Thanks Danny. Those are good points. I think it depends on what we consider hint as. IMHO, if we consider hint as a kind of metadata, it is not a good idea to store the hints in the RelNode instance. Best, Chunwei On Wed, Apr 24, 2019 at 11:09 AM Yuzhao Chen wrote: > > Thx, Julian > > I

Re: How to traverse RelNode’s parent conviniently?

Thx, Julian I think the hint path is a good way for searching RelNode’s parents, broadly, there may be these modules/things need to be modified: 1. Supports hints grammar for parser.jj 2. Cache the hints in the RelNode instance, and add method like RelNode#getHints() to fetch all the hints

Re: How to traverse RelNode’s parent conviniently?

I see that if you have a hint on, say, the root node then it would be nice for its child or grand-child to be able to see that hint. How about giving each hint an inherit path? Thus given Filter Hint1 +- Join +- Scan +- Project Hint2 +- Scan Filter would have hints

Re: How to traverse RelNode’s parent conviniently?

Thx, Andrew I don’t want to have a custom RelNode class, I hope all the work about hints would be contributed to the community. I want to find an acceptable way to keep and propagate the hints if we use the MetadataHandler to cache and query the hints. I don’t think the hints should be mixed

Re: How to traverse RelNode’s parent conviniently?

Hi Danny, I would also agree with Julian on his position. I've tried to get around this limitation in several different ways, but none of it ended well :) For your idea with hints, if you have custom RelNode classes, you can add hint as an additional field of the class and you can write a simple

Re: How to traverse RelNode’s parent conviniently?

Julian, I want to add hint support for Calcite, the initial idea was to tag a RelNode(transformed from a SqlNode with hint) with a hit attribute(or trait), then I hope that the children (inputs) of it can see this hint, so to make some decisions if it should consume or propagate the hint. The

Re: How to traverse RelNode’s parent conviniently?

TL;DR: RelNodes don’t really have parents. Be careful if you are relying on the parent concept too much. Rely on rules instead. In the Volcano model, a RelNode doesn’t really have a parent. It might be used in several places. (RelSet has a field ‘List parents’ that is kept up to date as

Re: How to traverse RelNode’s parent conviniently?

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)        /  

Re: How to traverse RelNode’s parent conviniently?

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]

How to traverse RelNode’s parent conviniently?

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