Hi Ruben, Thank you very much for your reply! Will I have to create a different Metadata Handler per operator (eg. Project, Correlate etc.) or can I make a common one?
Also, I am having some trouble finding where to put this statement: ChainedRelMetadataProvider.of(ImmutableList.of(YourRelMdNonCumulativeCost.INSTANCE, DefaultRelMetadataProvider.INSTANCE)); Could you please help me out by pointing me to a code example? I viewed this tutorial: https://www.youtube.com/watch?v=p1O3E33FIs8, but nowhere in the query processing code do I see where to put this (it is mentioned in the architecture though). Thanks & Regards, Pranav On Sat, Sep 17, 2022 at 6:07 AM Ruben Q L <[email protected]> wrote: > Hello Pranav, > > If you just need to "override" the cost function of certain operators, > there is no need to create new operators (and rules), you can do that by > extending the Metadata. > Let's say you want to override the cost of the Correlate, you should be > able to do that by creating your own class: > > public final class YourRelMdNonCumulativeCost implements > MetadataHandler<NonCumulativeCost> > { > static final RelMetadataProvider INSTANCE = > ReflectiveRelMetadataProvider.reflectiveSource(new > YourRelMdNonCumulativeCost(), > BuiltInMetadata.NonCumulativeCost.Handler.class); > > private YourRelMdNonCumulativeCost() { } > > @Override > public MetadataDef<NonCumulativeCost> getDef() { return > NonCumulativeCost.DEF; } > > public RelOptCost getNonCumulativeCost(Correlate correlate, > RelMetadataQuery mq) > { > // your code here... > } > } > > And then as MetadataProvider, instead of using just Calcite's default one, > you would use a chain of yours + Calcite's default: > > > ChainedRelMetadataProvider.of(ImmutableList.of(YourRelMdNonCumulativeCost.INSTANCE, > DefaultRelMetadataProvider.INSTANCE)); > > > Having said that, if you really need to create your own operators, the > easiest way, as you mention, is to create your operator (which would extend > the Calcite operator) and your rule (which could extend the Calcite rule, > but not necessarily). As you say, it is not possible to use the > Immutable*Rule Config, but you can use the rule's default Config or create > your own default Config. You can even do all that without Immutables in > your project, this thread might be of interest [1]. > > Best, > Ruben > > [1] https://lists.apache.org/thread/2h0mcdqs4q1psgjy9sxlk8wxzo3w1zq9 > > > > On Fri, Sep 16, 2022 at 10:10 PM Pranav Deshpande < > [email protected]> wrote: > > > Hi Julian/Apache Calcite Dev Team, > > Thank you very much for your reply > > I see that's a good point and it makes a lot of sense. I think I should > > exactly tell you what my problem is: I am only trying to override the > cost > > function so that I can group operators in a certain way in the Relational > > Tree. > > > > That is the only functionality that is required (for my example) right > now. > > I was extending the rules and the nodes to override this 1 function only. > > Is there another way to do this? If not, what is the recommended approach > > (is it to duplicate the enumerable rels and rules)? > > > > Please let me know. > > > > Thanks & Regards, > > Pranav > > > > On Fri, Sep 16, 2022 at 3:13 PM Julian Hyde <[email protected]> > > wrote: > > > > > We don’t necessary want you to extend existing classes. If we change > the > > > base class in future, your code breaks, and you complain that we have > > > broken semantic versioning. Making things private is, in that sense, a > > > feature. > > > > > > If what you are doing is a feature that would benefit other Calcite > > users, > > > you should propose that feature. > > > > > > Julian > > > > > > > > > > On Sep 16, 2022, at 11:41 AM, Pranav Deshpande < > > > [email protected]> wrote: > > > > > > > > Dear Apache Calcite Team, > > > > I am trying to modify some parts of the RelNode Tree in Calcite for > my > > > own > > > > custom logic. For this, I am extending existing nodes (eg. > > > > EnumerableAggregate etc.) and then also extending the respective rule > > > (eg. > > > > EnumerableAggregateRule) and overriding the respective functions in > > both > > > so > > > > that my custom node is used in the tree (logical -> custom node which > > is > > > > basically an extended enumerable) instead of logical -> enumerable. > > > > > > > > Some of the rules here (eg. EnumerableLimit) have references to > > Immutable > > > > classes which are package private and I hence I am unable to extend > > these > > > > (EnumerableLimitRule is itself one such example: > > > > > > > > > > https://github.com/apache/calcite/blob/b9c2099ea92a575084b55a206efc5dd341c0df62/core/src/main/java/org/apache/calcite/adapter/enumerable/EnumerableLimitRule.java#L72 > > > > ) > > > > > > > > Any advice on how I can solve this problem? > > > > > > > > Thanks & Regards, > > > > Pranav > > > > > > > > >
