add deregister schema

Author: Jan Kaul

datafusion_iceberg/src/catalog/catalog.rs

@@ -70,4 +70,16 @@ impl CatalogProvider for IcebergCatalog {
             Ok(None)
         }
     }
+
+    fn deregister_schema(
+        &self,
+        name: &str,
+        _cascade: bool,
+    ) -> Result<Option<Arc<dyn SchemaProvider>>> {
+        if self.catalog.deregister_schema(name)?.is_some() {
+            Ok(self.schema(name))
+        } else {
+            Ok(None)
+        }
+    }
 }

datafusion_iceberg/src/catalog/mirror.rs

@@ -217,4 +217,14 @@ impl Mirror {
             .insert(namespace.to_string(), Node::Namespace(HashSet::new()));
         Ok(old_value)
     }
+
+    pub fn deregister_schema(&self, name: &str) -> Result<Option<NamespaceNode>, DataFusionError> {
+        match self.storage.remove(name) {
+            Some((_, Node::Namespace(namespace))) => Ok(Some(namespace)),
+            None => Ok(None),
+            _ => Err(DataFusionError::from(Error::from(
+                IcebergError::InvalidFormat("Schema to drop".to_owned()),
+            ))),
+        }
+    }
 }