overview section, examples and joins

[pmaria]

resolves #74

[DylanVanAssche]

Looks fine to me!

[dachafra]

it looks good, although I don't know if the part in the equality of joins is enough... maybe add an example where they are the same?

[pmaria]

it looks good, although I don't know if the part in the equality of joins is enough... maybe add an example where they are the same?

@dachafra the first example is using the same logical source. But I think you mean, an example where they are not the same, but are effectively equal?

[elsdvlee]

One last thought. See the test case proposed here: https://github.com/kg-construct/rml-core/compare/testcase_self_join_with_join_condition.
What happens in case of effectively equal logical sources AND join conditions? Do we need to add a note to make sure that this is not misunderstood, and also add a test case? Today some engines handle this differently.

[pmaria]

One last thought. See the test case proposed here: https://github.com/kg-construct/rml-core/compare/testcase_self_join_with_join_condition.
What happens in case of effectively equal logical sources AND join conditions? Do we need to add a note to make sure that this is not misunderstood, and also add a test case? Today some engines handle this differently.

I don't see a way to test this, since it is part of the mapping process implemented by a processor. It is basically something a processor could detect and optimize on. We could add a note about this, but not sure it is necessary.

[elsdvlee]

One last thought. See the test case proposed here: https://github.com/kg-construct/rml-core/compare/testcase_self_join_with_join_condition.
What happens in case of effectively equal logical sources AND join conditions? Do we need to add a note to make sure that this is not misunderstood, and also add a test case? Today some engines handle this differently.

I don't see a way to test this, since it is part of the mapping process implemented by a processor. It is basically something a processor could detect and optimize on. We could add a note about this, but not sure it is necessary.

I checked the published test cases and noticed that the test case which I proposed is included, so all fine!