mingmwang commented on code in PR #4443:
URL: https://github.com/apache/arrow-datafusion/pull/4443#discussion_r1041728697
##########
datafusion/expr/src/logical_plan/builder.rs:
##########
@@ -1012,6 +1013,68 @@ pub fn table_scan(
LogicalPlanBuilder::scan(name.unwrap_or(UNNAMED_TABLE), table_source,
projection)
}
+/// Wrap projection for a plan, if the join keys contains normal expression.
+pub fn wrap_projection_for_join_if_necessary(
+ join_keys: &[Expr],
+ input: LogicalPlan,
+) -> Result<(LogicalPlan, Vec<Column>, bool)> {
+ let input_schema = input.schema();
+ let alias_join_keys: Vec<Expr> = join_keys
+ .iter()
+ .map(|key| {
+ // The display_name() of cast expression will ignore the cast
info, and show the inner expression name.
+ // If we do not add alais, it will throw same field name error in
the schema when adding projection.
+ // For example:
+ // input scan : [a, b, c],
+ // join keys: [cast(a as int)]
+ //
+ // then a and cast(a as int) will use the same field name - `a`
in projection schema.
Review Comment:
Why the `Cast` expressions ignore the cast info ? Looks like this is not the
expected behavior.
I think no matter the Cast is explicit or implicit, it should display the
cast info.
https://github.com/apache/arrow-datafusion/blob/cedb05aedf3cea030bfa8774b8575d8f4806a1c8/datafusion/expr/src/expr.rs#L1108-L1115
@andygrove @liukun4515 @jackwener
How do you think?
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