[Rust][Datafusion] Casting from Un-signed to Signed Integers not supported

[asfimport]

The following code reproduces the issue:

https://gist.github.com/paddyhoran/598db6cbb790fc5497320613e54a02c6

If you disable the predicate push down optimization it works fine.

Reporter: Paddy Horan / @paddyhoran
Assignee: Paddy Horan / @paddyhoran

PRs and other links:

• GitHub Pull Request #5224

_{Note: This issue was originally created as ARROW-6372. Please see the migration documentation for further details.}

[asfimport]

Andy Grove / @andygrove:
Thanks Paddy. Here is a unit test to reproduce this (can be added to type_coercion.rs):

#[test]
fn test_add_u32_i64() {
    binary_cast_test(
        DataType::UInt32,
        DataType::Int64,
        "CAST(#0 AS Int64) Plus #1",
    );
    binary_cast_test(
        DataType::Int64,
        DataType::UInt32,
        "#0 Plus CAST(#1 AS Int64)",
    );
} 

The issue is that the can_coerce_from function in datafusion/src/logicalplan.rs does not support automatic coercion between signed and unsigned types, and is inconsistent with the logic in the get_supertype method in datafusion/src/optimizer/utils.rs.

This is also somewhat related to https://issues.apache.org/jira/browse/ARROW-4957

[asfimport]

Andy Grove / @andygrove:
If nobody picks this up before the weekend, I will resolve it then. Really we need to make get_supertype and can_coerce_from consistent and better implemented (it's pretty hacky right now and only supports a subset of data types).

[asfimport]

Andy Grove / @andygrove:
Another note on this ... in this case we have one expression that references a column and one that is a literal ... in this case the type of the column should take precedence and the literal value (Int64) should be cast to the type of the column (UInt32). The literal is Int64 just because that's the type the SQL parser uses for any literal integers.

[asfimport]

Paddy Horan / @paddyhoran:
Oh that's interesting.  I was trying to give a minimal example of an issue I am having in another project and I believe the example highlights a different issue.

I'll take this one on, I thought it was more complex.

[asfimport]

Krisztian Szucs / @kszucs:
Issue resolved by pull request 5224
#5224