WIP

crates/iceberg/src/error.rs

@@ -44,6 +44,11 @@ pub enum ErrorKind {
     ///
     /// This error is returned when given iceberg feature is not supported.
     FeatureUnsupported,
+    /// Validation failed.
+    ///
+    /// This error is returned when Table or View Metadata is manipulated
+    /// in non-allowed ways.
+    ValidationFailed,
 }
 
 impl ErrorKind {
@@ -59,6 +64,7 @@ impl From<ErrorKind> for &'static str {
             ErrorKind::Unexpected => "Unexpected",
             ErrorKind::DataInvalid => "DataInvalid",
             ErrorKind::FeatureUnsupported => "FeatureUnsupported",
+            ErrorKind::ValidationFailed => "ValidationFailed",
         }
     }
 }

crates/iceberg/src/spec/mod.rs

@@ -25,6 +25,7 @@ mod schema;
 mod snapshot;
 mod sort;
 mod table_metadata;
+mod table_metadata_builder;
 mod transform;
 mod values;
 mod view_metadata;

crates/iceberg/src/spec/schema.rs

@@ -347,6 +347,19 @@ impl Schema {
     pub fn accessor_by_field_id(&self, field_id: i32) -> Option<Arc<StructAccessor>> {
         self.field_id_to_accessor.get(&field_id).cloned()
     }
+
+    /// Check if this schema is identical to another schema semantically - excluding schema id.
+    pub fn is_same_schema(&self, other: &SchemaRef) -> bool {
+        self.as_struct().eq(other.as_struct())
+            && self.identifier_field_ids().eq(other.identifier_field_ids())
+    }
+
+    /// Change the schema id of this schema.
+    // This is redundant with the `with_schema_id` method on the builder, but useful
+    // as it is infallible in contrast to the builder `build()` method.
+    pub(crate) fn with_schema_id(self, schema_id: SchemaId) -> Self {
+        Self { schema_id, ..self }
+    }
 }
 
 impl Display for Schema {

crates/iceberg/src/spec/table_metadata.rs

@@ -117,6 +117,12 @@ pub struct TableMetadata {
 }
 
 impl TableMetadata {
+    /// Convert this Table Metadata into a builder for modification
+    #[must_use]
+    pub fn into_builder(self) -> super::table_metadata_builder::TableMetadataBuilder {
+        super::table_metadata_builder::TableMetadataBuilder::new_from_metadata(self)
+    }
+
     /// Returns format version of this metadata.
     #[inline]
     pub fn format_version(&self) -> FormatVersion {
@@ -258,6 +264,7 @@ impl TableMetadata {
 
     /// Append snapshot to table
     pub fn append_snapshot(&mut self, snapshot: Snapshot) {
+        // ToDo: Fix - support more branches? Required if we have the new builder?
         self.last_updated_ms = snapshot.timestamp().timestamp_millis();
         self.last_sequence_number = snapshot.sequence_number();