[GitHub] [arrow-datafusion] andygrove commented on a change in pull request #55: Support qualified columns in queries

[GitBox <gi...@apache.org>]

andygrove commented on a change in pull request #55:
URL: https://github.com/apache/arrow-datafusion/pull/55#discussion_r619815966



##########
File path: datafusion/src/logical_plan/expr.rs
##########
@@ -27,14 +27,89 @@ use aggregates::{AccumulatorFunctionImplementation, StateTypeFunction};
 use arrow::{compute::can_cast_types, datatypes::DataType};
 
 use crate::error::{DataFusionError, Result};
-use crate::logical_plan::{DFField, DFSchema};
+use crate::logical_plan::{DFField, DFSchema, DFSchemaRef};
 use crate::physical_plan::{
     aggregates, expressions::binary_operator_data_type, functions, udf::ScalarUDF,
 };
 use crate::{physical_plan::udaf::AggregateUDF, scalar::ScalarValue};
 use functions::{ReturnTypeFunction, ScalarFunctionImplementation, Signature};
 use std::collections::HashSet;
 
+/// A named reference to a qualified filed in a schema.
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct Column {
+    /// relation/table name.
+    pub relation: Option<String>,
+    /// field/column name.
+    pub name: String,

Review comment:
       Should we consider supporting compound names here so that we can eventually support reference nested types?
   
   Perhaps Column could be an enum?
   
   ```rust
   enum Column {
     Simple(Option<String>, String),
     Compound(Option<String>, Vec<String>)
   }
   ```
   
   




-- 
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

For queries about this service, please contact Infrastructure at:
users@infra.apache.org