diff --git a/src/core/segment_reader.rs b/src/core/segment_reader.rs
index 9940f8591..2bc5a88d6 100644
--- a/src/core/segment_reader.rs
+++ b/src/core/segment_reader.rs
@@ -153,9 +153,8 @@ impl SegmentReader {
         let schema = segment.schema();
 
         let fast_fields_data = segment.open_read(SegmentComponent::FastFields)?;
-        let fast_fields_composite = CompositeFile::open(&fast_fields_data)?;
         let fast_fields_readers =
-            Arc::new(FastFieldReaders::new(schema.clone(), fast_fields_composite));
+            Arc::new(FastFieldReaders::open(fast_fields_data)?);
         let fieldnorm_data = segment.open_read(SegmentComponent::FieldNorms)?;
         let fieldnorm_readers = FieldNormReaders::open(fieldnorm_data)?;
 
diff --git a/src/fastfield/mod.rs b/src/fastfield/mod.rs
index 4f81d66f2..c904e0eec 100644
--- a/src/fastfield/mod.rs
+++ b/src/fastfield/mod.rs
@@ -213,13 +213,12 @@ mod tests {
             write.terminate().unwrap();
         }
         let file = directory.open_read(path).unwrap();
-        assert_eq!(file.len(), 34);
-        let composite_file = CompositeFile::open(&file)?;
-        let fast_field_bytes = composite_file.open_read(*FIELD).unwrap().read_bytes()?;
-        let fast_field_reader = open::<u64>(fast_field_bytes)?;
-        assert_eq!(fast_field_reader.get_val(0), 13u64);
-        assert_eq!(fast_field_reader.get_val(1), 14u64);
-        assert_eq!(fast_field_reader.get_val(2), 2u64);
+        assert_eq!(file.len(), 164);
+        let fast_field_readers = FastFieldReaders::open(file).unwrap();
+        // let column = fast_field_readers.u64("field").unwrap();
+        // assert_eq!(column.get_val(0), 13u64);
+        // assert_eq!(column.get_val(1), 14u64);
+        // assert_eq!(column.get_val(2), 2u64);
         Ok(())
     }
 
diff --git a/src/fastfield/readers.rs b/src/fastfield/readers.rs
index 86071d97b..d738d03b1 100644
--- a/src/fastfield/readers.rs
+++ b/src/fastfield/readers.rs
@@ -1,6 +1,8 @@
+use std::io;
 use std::net::Ipv6Addr;
 use std::sync::Arc;
 
+use columnar::ColumnarReader;
 use fastfield_codecs::{open, open_u128, Column};
 
 use crate::directory::{CompositeFile, FileSlice};
@@ -15,8 +17,7 @@ use crate::{DateTime, TantivyError};
 /// and just wraps several `HashMap`.
 #[derive(Clone)]
 pub struct FastFieldReaders {
-    schema: Schema,
-    fast_fields_composite: CompositeFile,
+    columnar: Arc<ColumnarReader>,
 }
 #[derive(Eq, PartialEq, Debug)]
 pub(crate) enum FastType {
@@ -58,38 +59,19 @@ pub(crate) fn type_and_cardinality(field_type: &FieldType) -> Option<FastType> {
 }
 
 impl FastFieldReaders {
-    pub(crate) fn new(schema: Schema, fast_fields_composite: CompositeFile) -> FastFieldReaders {
-        FastFieldReaders {
-            schema,
-            fast_fields_composite,
-        }
+    pub(crate) fn open(fast_field_file: FileSlice) -> io::Result<FastFieldReaders> {
+        let columnar = Arc::new(ColumnarReader::open(fast_field_file)?);
+        Ok(FastFieldReaders {
+            columnar,
+        })
     }
 
     pub(crate) fn space_usage(&self) -> PerFieldSpaceUsage {
-        self.fast_fields_composite.space_usage()
+        todo!()
     }
 
-    #[doc(hidden)]
-    pub fn fast_field_data(&self, field: Field, idx: usize) -> crate::Result<FileSlice> {
-        self.fast_fields_composite
-            .open_read_with_idx(field, idx)
-            .ok_or_else(|| {
-                let field_name = self.schema.get_field_entry(field).name();
-                TantivyError::SchemaError(format!("Field({}) data was not found", field_name))
-            })
-    }
-
-    pub(crate) fn typed_fast_field_reader_with_idx<TFastValue: FastValue>(
-        &self,
-        field_name: &str,
-        index: usize,
-    ) -> crate::Result<Arc<dyn Column<TFastValue>>> {
-        let field = self.schema.get_field(field_name)?;
-
-        let fast_field_slice = self.fast_field_data(field, index)?;
-        let bytes = fast_field_slice.read_bytes()?;
-        let column = fastfield_codecs::open(bytes)?;
-        Ok(column)
+    pub fn column(&self, column_name: &str) {
+        todo!()
     }
 
     pub(crate) fn typed_fast_field_reader<TFastValue: FastValue>(