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https://issues.apache.org/jira/browse/ARROW-9809?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17181273#comment-17181273
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Andy Grove commented on ARROW-9809:
-----------------------------------
It seems that we should determine data types and nullability only in the
logical plan and then pass that information to the physical plan rather than
re-compute them there. I think this is what you have been suggesting already
[~jorgecarleitao] ?
> [Rust] [DataFusion] logical schema = physical schema is not true
> ----------------------------------------------------------------
>
> Key: ARROW-9809
> URL: https://issues.apache.org/jira/browse/ARROW-9809
> Project: Apache Arrow
> Issue Type: Bug
> Components: Rust, Rust - DataFusion
> Reporter: Jorge
> Priority: Major
>
> In tests/sql.rs, we test that the physical and the optimized schema must
> match. However, this is not necessarily true for all our queries. An example:
> {code:java}
> #[test]
> fn csv_query_sum_cast() {
> let mut ctx = ExecutionContext::new();
> register_aggregate_csv_by_sql(&mut ctx);
> // c8 = i32; c9 = i64
> let sql = "SELECT c8 + c9 FROM aggregate_test_100";
> // check that the physical and logical schemas are equal
> execute(&mut ctx, sql);
> }
> {code}
> The physical expression (and schema) of this operation, after optimization,
> is {{CAST(c8 as Int64) Plus c9}} (this test fails).
> AFAIK, the invariant of the optimizer is that the output types and
> nullability are the same.
> Also, note that the reason the optimized logical schema equals the logical
> schema is that our type coercer does not change the output names of the
> schema, even though it re-writes logical expressions. I.e. after the
> optimization, `.to_field()` of an expression may no longer match the field
> name nor type in the Plan's schema. IMO this is currently by (implicit?)
> design, as we do not want our logical schema's column names to change during
> optimizations, or all column references may point to non-existent columns.
> This is something that brought up on the mailing list about polymorphism.
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