diff --git a/src/main.rs b/src/main.rs
index 24bd221..d352dcd 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -233,8 +233,10 @@ fn main() {
     action();
 }
 
+type LSize = u32;
+const LEN_SIZE: usize = std::mem::size_of::<LSize>();
+
 fn read_from_db2(id: u32) -> Option<Question> {
-    const LEN_SIZE: usize = std::mem::size_of::<u32>();
     let cfg = bincode::config::standard();
 
     let input = fs::File::open("test.bin").expect("open input");
@@ -242,7 +244,7 @@ fn read_from_db2(id: u32) -> Option<Question> {
 
     let mut len_data: [u8; LEN_SIZE] = [0; LEN_SIZE];
     input.read_exact(&mut len_data).expect("read len");
-    let tab_len = u32::from_le_bytes(len_data) as usize;
+    let tab_len = LSize::from_le_bytes(len_data) as usize;
     let records_count = tab_len - 1;
 
     // println!(
@@ -274,15 +276,15 @@ fn read_from_db2(id: u32) -> Option<Question> {
         .expect("read current pos");
     input.read_exact(&mut pos_next_data).expect("read next pos");
 
-    let data_pos = u32::from_le_bytes(pos_curr_data);
-    let data_pos_next = u32::from_le_bytes(pos_next_data);
+    let data_pos = LSize::from_le_bytes(pos_curr_data);
+    let data_pos_next = LSize::from_le_bytes(pos_next_data);
     let data_len = data_pos_next - data_pos;
 
     // println!(
     //     "pos {} | next {} | len {} | tab_tail_len {}",
     //     data_pos, data_pos_next, data_len, tab_tail_len
     // );
-    let data_pos = data_pos + tab_tail_len as u32;
+    let data_pos = data_pos + tab_tail_len as LSize;
 
     input.seek_relative(data_pos as i64).expect("q seek");
     let reader = input.take(data_len as u64);
@@ -309,16 +311,15 @@ fn write_db2() {
     println!("all done");
 }
 fn db_writer2_task(rx: mpsc::Receiver<Question>) {
-    const LEN_SIZE: usize = std::mem::size_of::<u32>();
     const COMP_DATA_LEVEL: i32 = 2;
 
     let cfg = bincode::config::standard();
-    let mut table: Vec<u32> = vec![];
+    let mut table: Vec<LSize> = vec![];
 
     let buf_data: Vec<u8> = Vec::with_capacity(500 * 1024 * 1024);
     use std::io::Cursor;
     let mut buf = Cursor::new(buf_data);
-    let mut pos: u32 = 0;
+    let mut pos: LSize = 0;
     let mut num = 1;
     rx.into_iter().for_each(|mut q| {
         q.num = num;
@@ -329,7 +330,7 @@ fn db_writer2_task(rx: mpsc::Receiver<Question>) {
 
         //println!("write [{}]: {}", num, pos);
 
-        pos += len as u32;
+        pos += len as LSize;
         num += 1;
     });
     table.push(pos);
@@ -345,7 +346,7 @@ fn db_writer2_task(rx: mpsc::Receiver<Question>) {
 
     let tab_data = vec![0u8; (table.len() + 1) * LEN_SIZE];
     let mut tab_cursor = Cursor::new(tab_data);
-    let len_data = (table.len() as u32).to_le_bytes();
+    let len_data = (table.len() as LSize).to_le_bytes();
     tab_cursor.write_all(&len_data).expect("write len");
     for pos in table {
         let pos_data = pos.to_le_bytes();