crepererum commented on code in PR #7870:
URL: https://github.com/apache/arrow-datafusion/pull/7870#discussion_r1374379563
##########
datafusion/common/src/dfschema.rs:
##########
@@ -35,11 +38,122 @@ use arrow::datatypes::{DataType, Field, FieldRef, Fields,
Schema, SchemaRef};
/// A reference-counted reference to a `DFSchema`.
pub type DFSchemaRef = Arc<DFSchema>;
+/// [`FieldReference`]s represent a multi part identifier (path) to a
+/// field that may require further resolution.
+#[derive(Debug, Clone, PartialEq, Eq)]
+struct FieldReference<'a> {
+ /// The field name
+ name: Cow<'a, str>,
+ /// Optional qualifier (usually a table or relation name)
+ qualifier: Option<TableReference<'a>>,
+}
+
+impl<'a> PartialOrd for FieldReference<'a> {
+ fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+ Some(self.cmp(other))
+ }
+}
+
+impl<'a> Ord for FieldReference<'a> {
+ fn cmp(&self, other: &Self) -> Ordering {
+ if self == other {
+ return Ordering::Equal;
+ }
+
+ match self.field().cmp(other.field()) {
+ Ordering::Less => return Ordering::Less,
+ Ordering::Greater => return Ordering::Greater,
+ Ordering::Equal => {}
+ }
+
+ match (self.table(), other.table()) {
+ (Some(lhs), Some(rhs)) => match lhs.cmp(rhs) {
+ Ordering::Less => return Ordering::Less,
+ Ordering::Greater => return Ordering::Greater,
+ Ordering::Equal => {}
+ },
+ (Some(_), None) => return Ordering::Greater,
+ (None, Some(_)) => return Ordering::Less,
+ _ => {}
+ }
+
+ match (self.schema(), other.schema()) {
+ (Some(lhs), Some(rhs)) => match lhs.cmp(rhs) {
+ Ordering::Less => return Ordering::Less,
+ Ordering::Greater => return Ordering::Greater,
+ Ordering::Equal => {}
+ },
+ (Some(_), None) => return Ordering::Greater,
+ (None, Some(_)) => return Ordering::Less,
+ _ => {}
+ }
+
+ match (self.catalog(), other.catalog()) {
+ (Some(lhs), Some(rhs)) => match lhs.cmp(rhs) {
+ Ordering::Less => return Ordering::Less,
+ Ordering::Greater => return Ordering::Greater,
+ Ordering::Equal => {}
+ },
+ (Some(_), None) => return Ordering::Greater,
+ (None, Some(_)) => return Ordering::Less,
+ _ => {}
+ }
+
+ Ordering::Equal
+ }
+}
+
+/// This is a [`FieldReference`] that has 'static lifetime (aka it
+/// owns the underlying strings)
+type OwnedFieldReference = FieldReference<'static>;
+
+impl<'a> FieldReference<'a> {
+ /// Convenience method for creating a [`FieldReference`].
+ pub fn new(
+ name: impl Into<Cow<'a, str>>,
+ qualifier: Option<TableReference<'a>>,
+ ) -> Self {
+ Self {
+ name: name.into(),
+ qualifier,
+ }
+ }
+
+ /// Compare with another [`FieldReference`] as if both are resolved.
+ /// This allows comparing across variants, where if a field is not present
+ /// in both variants being compared then it is ignored in the comparison.
+ pub fn resolved_eq(&self, other: &Self) -> bool {
+ self.name == other.name
+ && match (&self.qualifier, &other.qualifier) {
+ (Some(lhs), Some(rhs)) => lhs.resolved_eq(rhs),
+ _ => true,
+ }
+ }
+
+ fn field(&self) -> &str {
+ &self.name
+ }
+
+ fn table(&self) -> Option<&str> {
+ self.qualifier.as_ref().map(|q| q.table())
+ }
+
+ fn schema(&self) -> Option<&str> {
+ self.qualifier.as_ref().and_then(|q| q.schema())
+ }
+
+ fn catalog(&self) -> Option<&str> {
+ self.qualifier.as_ref().and_then(|q| q.catalog())
+ }
+}
+
/// DFSchema wraps an Arrow schema and adds relation names
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct DFSchema {
/// Fields
fields: Vec<DFField>,
+ /// Fields index
+ fields_index: BTreeMap<OwnedFieldReference, Vec<usize>>,
Review Comment:
we do you care about the index order? You either iterate over the fields in
order (use `self.fields.iter()`) or you lookup a field by name (use
`self.field_index.get(...)`). The index is orderd by field name. So this
argument would only be valid if we OFTEN iterate over the fields in name order,
which I don't think we do.
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