diff --git a/Cargo.toml b/Cargo.toml
index ce2fe204b..b5c31321b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -10,3 +10,4 @@ memmap = "0.2.3"
 lazy_static = "0.1.*"
 regex = "0.1"
 fst = "0.1.26"
+rand = "0.3.13"
diff --git a/src/core/directory.rs b/src/core/directory.rs
index 14f2e9733..7af731685 100644
--- a/src/core/directory.rs
+++ b/src/core/directory.rs
@@ -9,9 +9,19 @@ use std::rc::Rc;
 use std::ops::Deref;
 use std::cell::RefCell;
 use std::sync::Arc;
+use rand::{thread_rng, Rng};
+
 
 #[derive(Clone, Debug)]
-pub struct SegmentId(String);
+pub struct SegmentId(pub String);
+
+pub fn generate_segment_name() -> SegmentId {
+    static CHARS: &'static [u8] = b"abcdefghijklmnopqrstuvwxyz0123456789";
+    let random_name: String = (0..8)
+            .map(|_| thread_rng().choose(CHARS).unwrap().clone() as char)
+            .collect();
+    SegmentId( String::from("_") + &random_name)
+}
 
 pub trait Dir {
     fn get_data(&self, segment_id: &SegmentId, component: SegmentComponent) -> Result<SharedMmapMemory, io::Error>; // {
@@ -30,6 +40,10 @@ impl Directory {
         }
     }
 
+    pub fn new_segment(&self,) -> Segment {
+        self.segment(&generate_segment_name())
+    }
+
     fn from<T: Dir + 'static>(directory: T) -> Directory {
         Directory {
             dir: Rc::new(directory),
diff --git a/src/core/writer.rs b/src/core/writer.rs
index b711d9ea0..4c88b1be9 100644
--- a/src/core/writer.rs
+++ b/src/core/writer.rs
@@ -31,32 +31,25 @@ impl PostingsWriter for SimplePostingsWriter {
 	}
 }
 
-impl Flushable for SimplePostingsWriter {
-	fn flush<W: Write>(&self, writer: &mut W) -> Result<usize, io::Error> {
-		let num_docs = self.doc_ids.len() as u64;
-		writer.write_u64::<NativeEndian>(num_docs);
-		for &doc_id in self.doc_ids.iter() {
-			writer.write_u64::<NativeEndian>(doc_id as u64);
-		}
-		Ok(1)
-	}
-}
 
 struct FieldWriter {
     postings: Vec<SimplePostingsWriter>,
     term_index: BTreeMap<String, usize>,
 }
-//
-// impl Flushable for FieldWriter {
-// 	fn flush<W: Write>(&self, writer: &mut W) -> Result<usize, io::Error> {
-// 		let num_docs = self.doc_ids.len() as u64;
-// 		writer.write_u64::<NativeEndian>(num_docs);
-// 		for &doc_id in self.doc_ids.iter() {
-// 			writer.write_u64::<NativeEndian>(doc_id as u64);
-// 		}
-// 		Ok(1)
-// 	}
-// }
+
+impl Flushable for SimplePostingsWriter {
+	fn flush<W: Write>(&self, writer: &mut W) -> Result<usize, io::Error> {
+		let mut num_bytes_written = 0;
+		let num_docs = self.doc_ids.len() as u64;
+		writer.write_u64::<NativeEndian>(num_docs);
+		num_bytes_written += 8;
+		for &doc_id in self.doc_ids.iter() {
+			writer.write_u64::<NativeEndian>(doc_id as u64);
+			num_bytes_written += 8;
+		}
+		Ok(num_bytes_written)
+	}
+}
 
 impl FieldWriter {
     pub fn new() -> FieldWriter {
@@ -120,6 +113,7 @@ impl IndexWriter {
     }
 
     pub fn sync(&mut self,) -> Result<(), io::Error> {
+		self.directory.new_segment();
         Ok(())
     }
 
diff --git a/src/lib.rs b/src/lib.rs
index 3f535347f..5b58ea342 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,5 +1,9 @@
 #[macro_use]
 extern crate lazy_static;
+
 extern crate byteorder;
 
+extern crate rand;
+extern crate regex;
+
 pub mod core;
diff --git a/tests/core.rs b/tests/core.rs
index 2f422a483..767e572b0 100644
--- a/tests/core.rs
+++ b/tests/core.rs
@@ -1,19 +1,21 @@
 extern crate tantivy;
 extern crate itertools;
 extern crate byteorder;
+extern crate regex;
 
 use tantivy::core::DocId;
 use tantivy::core::postings::{VecPostings, intersection};
 use tantivy::core::postings::Postings;
 use tantivy::core::analyzer::tokenize;
 use tantivy::core::writer::IndexWriter;
-use tantivy::core::directory::Directory;
+use tantivy::core::directory::{Directory, generate_segment_name, SegmentId};
 use tantivy::core::schema::{Field, Document};
 use tantivy::core::reader::IndexReader;
 use tantivy::core::writer::SimplePostingsWriter;
 use tantivy::core::postings::PostingsWriter;
 use tantivy::core::global::Flushable;
-use std::io::{ BufWriter, Write };
+use std::io::{ BufWriter, Write};
+use regex::Regex;
 use std::convert::From;
 
 #[test]
@@ -58,3 +60,10 @@ fn test_postings_writer() {
     postings_writer.flush(&mut buffer);
     assert_eq!(buffer.len(), 5 * 8);
 }
+
+#[test]
+fn test_new_segment() {
+    let SegmentId(segment_name) = generate_segment_name();
+    let segment_ptn = Regex::new(r"^_[a-z0-9]{8}$").unwrap();
+    assert!(segment_ptn.is_match(&segment_name));
+}