Incorrect/inconsistent cardinality calculation

[pulquero]

EvaluationStatistics.getCardinality() should use Set vars = pattern.getVars(new HashSet<>()) else
?s ?p ?o and ?s ?s ?s are considered to have the same cardinality.

[hmottestad]

@pulquero can you provide a link to the exact line in the code in github?

[pulquero]

Sry, it's actually in the fed version not the main one.

https://github.com/eclipse/rdf4j/blob/d2a301dabcf9c051b019e3434327c15c29fc321e/core/sail/federation/src/main/java/org/eclipse/rdf4j/sail/federation/optimizers/EvaluationStatistics.java#L84

[hmottestad]

Thanks

[reeshabhranjan]

Can I work on this issue?

[barthanssens]

Sure, it's an open source project, and any help is welcome and much appreciated.

If this is your first contribution to RDF4J, there is one small but necessary thing you have to do: register for a (free) Eclipse account and sign a form

See "Legal stuff" in https://github.com/eclipse/rdf4j/blob/master/.github/CONTRIBUTING.md

[hmottestad]

@aschwarte10 is this class org.eclipse.rdf4j.sail.federation.optimizers.EvaluationStatistics used by FedX?

[reeshabhranjan]

So as per I understood the code, and the solution suggested in this issue, I just need to make sure that only distinct elements are in the vars list in this line, right?

[hmottestad]

So as per I understood the code, and the solution suggested in this issue, I just need to make sure that only distinct elements are in the vars list in this line, right?

I believe that is what is required. A test would also be nice.

[reeshabhranjan]

Alright, I will link a pull-request for this shortly.

[reeshabhranjan]

Sure, it's an open source project, and any help is welcome and much appreciated.

If this is your first contribution to RDF4J, there is one small but necessary thing you have to do: register for a (free) Eclipse account and sign a form

See "Legal stuff" in https://github.com/eclipse/rdf4j/blob/master/.github/CONTRIBUTING.md

Thank you @barthanssens for linking the legal procedures.

[reeshabhranjan]

I have made some changes to the code (here).
I think since Var has both hashCode and equals defined, the HashSet will handle the duplicate elements.
If this is fine, I would like to proceed with the tests. Also, this will be my first contribution for this repository, so I am a bit unsure about where to write the tests. Should I make a new file under

<project-root>/testsuites/sail/src/main/java/org/eclipse/rdf4j/sail ?

[hmottestad]

How about in a new package optimizers in core/sail/federation/src/test/java/org/eclipse/rdf4j/sail/federation?

[reeshabhranjan]

Alright, I will create a package optimizers and will create a test-file in it.

[reeshabhranjan]

I missed adding the issue number in my first commit, so is that fine or should I do something about it?

[hmottestad]

You can always edit your commit messages afterwards and also squash multiple commits together. Just don't merge anything into your branch.

More importantly is that you sign off on your commits.

Every commit you make in your patch or pull request MUST be "signed off". You do this by adding the -s flag when you make the commit(s).

I found this helpful guide if you've never used sign off before: https://docs.pi-hole.net/guides/github/how-to-signoff/

[reeshabhranjan]

I have linked the pull-request, kindly review it and let me know of any suggestions.