jiacai2050 commented on a change in pull request #1914:
URL: https://github.com/apache/arrow-datafusion/pull/1914#discussion_r820246063
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File path: datafusion-common/src/dfschema.rs
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@@ -36,16 +36,30 @@ pub type DFSchemaRef = Arc<DFSchema>;
pub struct DFSchema {
/// Fields
fields: Vec<DFField>,
+ /// Additional metadata in form of key value pairs
+ metadata: HashMap<String, String>,
}
impl DFSchema {
/// Creates an empty `DFSchema`
pub fn empty() -> Self {
- Self { fields: vec![] }
+ Self {
+ fields: vec![],
+ metadata: HashMap::new(),
+ }
}
+ #[deprecated(since = "7.0.0", note = "please use `new_with_metadata`
instead")]
/// Create a new `DFSchema`
pub fn new(fields: Vec<DFField>) -> Result<Self> {
+ Self::new_with_metadata(fields, HashMap::new())
+ }
+
+ /// Create a new `DFSchema`
+ pub fn new_with_metadata(
Review comment:
Builder-style API is good itself, but is not suitable here I think.
As you can see, schema conversion between Array and datafusion is used in
many places, the compiler will output an warning when `new` is marked as
deprecated, but when adopt builder-style API, no warning will be made, and it
would be very easy to lost metadata when doing nested conversion.
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