diff --git a/engine/persistent_storage_worker.go b/engine/persistent_storage_worker.go
deleted file mode 100644
index 69835c5..0000000
--- a/engine/persistent_storage_worker.go
+++ /dev/null
@@ -1,66 +0,0 @@
-package engine
-
-import (
-	"bytes"
-	"encoding/binary"
-	"encoding/gob"
-	"github.com/huichen/wukong/types"
-	"sync/atomic"
-)
-
-type persistentStorageIndexDocumentRequest struct {
-	docId uint64
-	data  types.DocumentIndexData
-}
-
-func (engine *Engine) persistentStorageIndexDocumentWorker(shard int) {
-	for {
-		request := <-engine.persistentStorageIndexDocumentChannels[shard]
-
-		// 得到key
-		b := make([]byte, 10)
-		length := binary.PutUvarint(b, request.docId)
-
-		// 得到value
-		var buf bytes.Buffer
-		enc := gob.NewEncoder(&buf)
-		err := enc.Encode(request.data)
-		if err != nil {
-			atomic.AddUint64(&engine.numDocumentsStored, 1)
-			continue
-		}
-
-		// 将key-value写入数据库
-		engine.dbs[shard].Set(b[0:length], buf.Bytes())
-		atomic.AddUint64(&engine.numDocumentsStored, 1)
-	}
-}
-
-func (engine *Engine) persistentStorageRemoveDocumentWorker(docId uint64, shard uint32) {
-	// 得到key
-	b := make([]byte, 10)
-	length := binary.PutUvarint(b, docId)
-
-	// 从数据库删除该key
-	engine.dbs[shard].Delete(b[0:length])
-}
-
-func (engine *Engine) persistentStorageInitWorker(shard int) {
-	engine.dbs[shard].ForEach(func(k, v []byte) error {
-		key, value := k, v
-		// 得到docID
-		docId, _ := binary.Uvarint(key)
-
-		// 得到data
-		buf := bytes.NewReader(value)
-		dec := gob.NewDecoder(buf)
-		var data types.DocumentIndexData
-		err := dec.Decode(&data)
-		if err == nil {
-			// 添加索引
-			engine.internalIndexDocument(docId, data, false)
-		}
-		return nil
-	})
-	engine.persistentStorageInitChannel <- true
-}