feat(writer): add delta writer (#18)

Co-authored-by: ZENOTME <st810918843@gmail.com>

fix

Author: ZENOTME

crates/iceberg/src/writer/base_writer/data_file_writer.rs

@@ -21,7 +21,7 @@ use arrow_array::RecordBatch;
 use itertools::Itertools;
 
 use crate::Result;
-use crate::spec::{DataContentType, DataFile, Struct};
+use crate::spec::{DataContentType, DataFile, SchemaRef, Struct};
 use crate::writer::file_writer::{FileWriter, FileWriterBuilder};
 use crate::writer::{CurrentFileStatus, IcebergWriter, IcebergWriterBuilder};
 
@@ -99,6 +99,10 @@ impl<B: FileWriterBuilder> CurrentFileStatus for DataFileWriter<B> {
     fn current_written_size(&self) -> usize {
         self.inner_writer.as_ref().unwrap().current_written_size()
     }
+
+    fn current_schema(&self) -> SchemaRef {
+        self.inner_writer.as_ref().unwrap().current_schema()
+    }
 }
 
 #[cfg(test)]

crates/iceberg/src/writer/file_writer/parquet_writer.rs

@@ -614,6 +614,10 @@ impl CurrentFileStatus for ParquetWriter {
             0
         }
     }
+
+    fn current_schema(&self) -> SchemaRef {
+        self.schema.clone()
+    }
 }
 
 /// AsyncFileWriter is a wrapper of FileWrite to make it compatible with tokio::io::AsyncWrite.

crates/iceberg/src/writer/file_writer/rolling_writer.rs

@@ -17,7 +17,7 @@
 
 use arrow_array::RecordBatch;
 
-use crate::spec::DataFileBuilder;
+use crate::spec::{DataFileBuilder, SchemaRef};
 use crate::writer::CurrentFileStatus;
 use crate::writer::file_writer::{FileWriter, FileWriterBuilder};
 use crate::{Error, ErrorKind, Result};
@@ -137,6 +137,10 @@ impl<B: FileWriterBuilder> CurrentFileStatus for RollingFileWriter<B> {
     fn current_written_size(&self) -> usize {
         self.inner.as_ref().unwrap().current_written_size()
     }
+
+    fn current_schema(&self) -> SchemaRef {
+        self.inner.as_ref().unwrap().current_schema()
+    }
 }
 
 #[cfg(test)]