lorenarosati opened a new pull request, #16950:
URL: https://github.com/apache/datafusion/pull/16950
## Which issue does this PR close?
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- Closes #16949.
## Rationale for this change
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the issue then this section is not needed.
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We've identified Substrait functions that have implementations in
DataFusion, but are not mapped to those functions because their names are
slightly different. For example, DataFusion does not understand the Substrait
is_nan function, because DataFusion's name for the same function is isnan, and
the Substrait consumer and producer work off of direct name mappings.
## What changes are included in this PR?
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sometimes worth providing a summary of the individual changes in this PR.
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- New mapping created in the consumer to map Substrait names to DataFusion
names
- Added new name mappings to the existing mapping of DataFusion names to
Substrait names; in the producer, the register_function() calls the
implementation of register_function() in Extensions, and this registers
function names with function anchors (so this is where mappings are added).
This PR adds mappings for the Substrait functions sign, is_nan, and logb,
but the same process can be done to add mappings for more functions.
## Are these changes tested?
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- Test added on the consumer side that consumes a scalar function and checks
if an error occurs
- Roundtrip test added that follows the structure of existing roundtrip
tests (testing both the producer and consumer) but includes a check that the
producer produced Substrait with the appropriate Substrait name.
- There's an [existing
test](https://github.com/apache/datafusion/blob/2a7f64a85e3d98c51c106607a425d73d2b839e82/datafusion/substrait/tests/cases/roundtrip_logical_plan.rs#L415)
that would test this roundtrip. Without this PR, this test would create an
intermediate Substrait plan with the wrong function name (when it calls
to_substrait_plan()) but the test would still pass because it would convert
back to the right DataFusion name. This test makes testing this change more
explicit, but feel free to let me know if this test is unnecessary / should be
removed / any other suggestion!
The roundtrip test tests is_nan function mappings, and the test on the
consumer side tests sign function mappings. It seems repetitive to run the same
test for all the newly added mappings, but I'm open to feedback on whether this
should be added!
## Are there any user-facing changes?
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updated before approving the PR.
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The Substrait consumer will be able to consume functions that previously
resulted in an unsupported function error, and the producer will produce
Substrait plans with the correct function names.
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change` label.
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