expose position delete schema and genreate snapshot id

Author: chenzl25

crates/iceberg/src/transaction/append.rs

@@ -68,6 +68,7 @@ impl FastAppendAction {
         self
     }
 
+    /// Set target branch for the snapshot.
     pub fn set_target_branch(mut self, target_branch: String) -> Self {
         self.target_branch = Some(target_branch);
         self
@@ -106,6 +107,7 @@ impl FastAppendAction {
         self
     }
 
+    /// Set snapshot id for the snapshot.
     pub fn set_snapshot_id(mut self, snapshot_id: i64) -> Self {
         self.snapshot_id = Some(snapshot_id);
         self

crates/iceberg/src/transaction/mod.rs

@@ -54,6 +54,8 @@ mod action;
 
 pub use action::*;
 mod append;
+
+pub use append::FastAppendAction;
 mod manifest_filter;
 
 pub use manifest_filter::*;
@@ -77,7 +79,7 @@ use rewrite_files::RewriteFilesAction;
 use crate::error::Result;
 use crate::spec::TableProperties;
 use crate::table::Table;
-use crate::transaction::append::{FastAppendAction, MergeAppendAction};
+use crate::transaction::append::MergeAppendAction;
 use crate::transaction::overwrite_files::OverwriteFilesAction;
 use crate::transaction::sort_order::ReplaceSortOrderAction;
 use crate::transaction::update_location::UpdateLocationAction;

crates/iceberg/src/transaction/snapshot.rs

@@ -708,14 +708,17 @@ impl<'a> SnapshotProducer<'a> {
         Ok(ActionCommit::new(updates, requirements))
     }
 
+    /// Set the new data file sequence number for this snapshot
     pub fn set_new_data_file_sequence_number(&mut self, new_data_file_sequence_number: i64) {
         self.new_data_file_sequence_number = Some(new_data_file_sequence_number);
     }
 
+    /// Set the target branch for this snapshot
     pub fn set_target_branch(&mut self, target_branch: String) {
         self.target_branch = target_branch;
     }
 
+    /// Get the target branch for this snapshot
     pub fn target_branch(&self) -> &str {
         &self.target_branch
     }

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

@@ -54,7 +54,8 @@ static DELETE_FILE_POS: Lazy<NestedFieldRef> = Lazy::new(|| {
         Type::Primitive(PrimitiveType::Long),
     ))
 });
-static POSITION_DELETE_SCHEMA: Lazy<Schema> = Lazy::new(|| {
+/// Iceberg schema used for position delete files (file_path, pos).
+pub static POSITION_DELETE_SCHEMA: Lazy<Schema> = Lazy::new(|| {
     Schema::builder()
         .with_fields(vec![DELETE_FILE_PATH.clone(), DELETE_FILE_POS.clone()])
         .build()