diff --git a/src/main/java/com/tencent/msdk/dns/core/cache/Cache.java b/src/main/java/com/tencent/msdk/dns/core/cache/Cache.java
index 7bac4eb..c4b4380 100644
--- a/src/main/java/com/tencent/msdk/dns/core/cache/Cache.java
+++ b/src/main/java/com/tencent/msdk/dns/core/cache/Cache.java
@@ -39,16 +39,17 @@ public static Cache getInstance() {
     public void readFromDb() {
         if (getCachedIpEnable()) {
             List<LookupCache> allCache = cacheDbHelper.getAll();
-            ArrayList<LookupCache> expired = new ArrayList<>();
+            ArrayList<String> expiredList = new ArrayList<>();
             for (LookupCache lookupCache : allCache) {
                 mHostnameIpsMap.put(lookupCache.hostname, lookupCache.lookupResult);
 
                 if (lookupCache.isExpired()) {
-                    expired.add(lookupCache);
+                    expiredList.add(lookupCache.hostname);
                 }
             }
+            String [] expiredHosts = expiredList.toArray(new String[expiredList.size()]);
             // 内存读取后，清空本地已过期的缓存
-            cacheDbHelper.deleteLookupCaches(expired);
+            cacheDbHelper.delete(expiredHosts);
         }
     }
 
@@ -88,7 +89,7 @@ public void add(String hostname, LookupResult lookupResult) {
         DnsLog.d("Cache %s for %s", lookupResult, hostname);
         mHostnameIpsMap.put(hostname, lookupResult);
         if (getCachedIpEnable()) {
-            cacheDbHelper.insertLookupCache(new LookupCache(hostname, lookupResult));
+            cacheDbHelper.insert(new LookupCache(hostname, lookupResult));
         }
     }
 
diff --git a/src/main/java/com/tencent/msdk/dns/core/cache/CacheDbHelper.java b/src/main/java/com/tencent/msdk/dns/core/cache/database/CacheDbHelper.java
similarity index 75%
rename from src/main/java/com/tencent/msdk/dns/core/cache/CacheDbHelper.java
rename to src/main/java/com/tencent/msdk/dns/core/cache/database/CacheDbHelper.java
index 0bf092a..53180ea 100644
--- a/src/main/java/com/tencent/msdk/dns/core/cache/CacheDbHelper.java
+++ b/src/main/java/com/tencent/msdk/dns/core/cache/database/CacheDbHelper.java
@@ -1,26 +1,26 @@
-package com.tencent.msdk.dns.core.cache;
+package com.tencent.msdk.dns.core.cache.database;
 
 import android.content.ContentValues;
 import android.content.Context;
 import android.database.Cursor;
 import android.database.sqlite.SQLiteDatabase;
 import android.database.sqlite.SQLiteOpenHelper;
+import android.text.TextUtils;
 
 import com.tencent.msdk.dns.base.log.DnsLog;
-import com.tencent.msdk.dns.core.cache.database.LookupCache;
-import com.tencent.msdk.dns.core.cache.database.LookupResultConverter;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 
 public class CacheDbHelper extends SQLiteOpenHelper {
     public static final int DATABASE_VERSION = 1;
 
-    public static final String DATABASE_NAME = "LookupCache.db";
+    public static final String DATABASE_NAME = "LookupResult.db";
 
-    private SQLiteDatabase mDb;
+    private static final Object mLock = new Object();
 
-    private final Object mLock = new Object();
+    private SQLiteDatabase mDb;
 
     static class DB {
         static final String TABLE_NAME = "lookupDB";
@@ -42,19 +42,18 @@ public CacheDbHelper(Context context) {
 
     private SQLiteDatabase getDb() {
         if (mDb == null) {
-            try{
+            try {
                 mDb = getWritableDatabase();
-            } catch (Exception e){
+            } catch (Exception e) {
 
             }
         }
         return mDb;
     }
 
-    public List<LookupCache> readFromDb() {
+    public List<LookupCache> getAll() {
         synchronized (mLock) {
             ArrayList<LookupCache> lists = new ArrayList<>();
-
             SQLiteDatabase db = null;
             Cursor cursor = null;
 
@@ -64,7 +63,6 @@ public List<LookupCache> readFromDb() {
                 if (cursor != null && cursor.getCount() > 0) {
                     cursor.moveToFirst();
                     do {
-                        DnsLog.d("testt----" + cursor.getString(cursor.getColumnIndex(DB.HOST))+ "result ---" + LookupResultConverter.toLookupResult(cursor.getBlob(cursor.getColumnIndex(DB.RESULT))));
                         lists.add(new LookupCache(
                                 cursor.getString(cursor.getColumnIndex(DB.HOST)),
                                 LookupResultConverter.toLookupResult(cursor.getBlob(cursor.getColumnIndex(DB.RESULT)))
@@ -85,7 +83,7 @@ public List<LookupCache> readFromDb() {
         }
     }
 
-    public void insertLookupCache(LookupCache lookupCache) {
+    public void insert(LookupCache lookupCache) {
         synchronized (mLock) {
             SQLiteDatabase db = null;
             try {
@@ -94,7 +92,7 @@ public void insertLookupCache(LookupCache lookupCache) {
                 ContentValues cv = new ContentValues();
                 cv.put(DB.HOST, lookupCache.hostname);
                 cv.put(DB.RESULT, LookupResultConverter.fromLookupResult(lookupCache.lookupResult));
-                db.insert(DB.TABLE_NAME, null, cv);
+                db.insertWithOnConflict(DB.TABLE_NAME, null, cv, SQLiteDatabase.CONFLICT_REPLACE);
                 db.setTransactionSuccessful();
             } catch (Exception e) {
                 DnsLog.e("insert lookupCache fail " + e);
@@ -109,27 +107,29 @@ public void insertLookupCache(LookupCache lookupCache) {
         }
     }
 
-    public void deleteLookupCaches(ArrayList<LookupCache> lookupCaches) {
-        for(LookupCache lookupCache: lookupCaches) {
-            delete(lookupCache.hostname);
-        }
+    public void delete(String hostname) {
+        delete(new String[]{hostname});
     }
 
-    public void delete(String hostname) {
-        synchronized (mLock) {
-            SQLiteDatabase db = null;
-            try {
-                db = getDb();
-                db.beginTransaction();
-                db.delete(DB.TABLE_NAME, DB.HOST + "= ? ", new String[] {hostname});
-                db.setTransactionSuccessful();
-            } catch (Exception e) {
-                DnsLog.e("delete by hostname fail" + e);
-            } finally {
-                if (db != null) {
-                    try {
-                        db.endTransaction();
-                    } catch (Exception ignored) {
+    public void delete(String[] hosts) {
+        if (hosts.length > 0) {
+            synchronized (mLock) {
+                SQLiteDatabase db = null;
+                try {
+                    db = getDb();
+                    db.beginTransaction();
+                    db.delete(DB.TABLE_NAME, DB.HOST + " IN (" + TextUtils.join(",", Collections.nCopies(hosts.length,
+                                    "?")) + ")",
+                            hosts);
+                    db.setTransactionSuccessful();
+                } catch (Exception e) {
+                    DnsLog.e("delete by hostname fail" + e);
+                } finally {
+                    if (db != null) {
+                        try {
+                            db.endTransaction();
+                        } catch (Exception ignored) {
+                        }
                     }
                 }
             }
@@ -161,7 +161,7 @@ public void clear() {
     public void onCreate(SQLiteDatabase db) {
         try {
             db.execSQL(DB.SQL_CREATE_ENTRIES);
-        }catch (Exception e) {
+        } catch (Exception e) {
             DnsLog.e("create db fail " + e);
         }
     }
diff --git a/src/main/java/com/tencent/msdk/dns/core/cache/database/LookupCache.java b/src/main/java/com/tencent/msdk/dns/core/cache/database/LookupCache.java
index 881aff1..d81a612 100644
--- a/src/main/java/com/tencent/msdk/dns/core/cache/database/LookupCache.java
+++ b/src/main/java/com/tencent/msdk/dns/core/cache/database/LookupCache.java
@@ -17,9 +17,6 @@ public LookupCache(@NonNull String mHostname, LookupResult mLookupResult) {
         this.lookupResult = mLookupResult;
     }
 
-    public LookupCache() {
-    }
-
     public boolean isExpired() {
         AbsRestDns.Statistics stat = (AbsRestDns.Statistics) lookupResult.stat;
         if (stat != null) {
diff --git a/src/main/java/com/tencent/msdk/dns/report/Session.java b/src/main/java/com/tencent/msdk/dns/report/Session.java
index b132df6..962e909 100644
--- a/src/main/java/com/tencent/msdk/dns/report/Session.java
+++ b/src/main/java/com/tencent/msdk/dns/report/Session.java
@@ -1,7 +1,5 @@
 package com.tencent.msdk.dns.report;
 
-import com.tencent.msdk.dns.base.log.DnsLog;
-
 import java.util.Random;
 
 public class Session {
@@ -15,7 +13,6 @@ public static void setSessionId() {
             buf[i] = sampleAlphabet.charAt(random.nextInt(sampleAlphabet.length()));
         }
         sessionId = new String(buf);
-        DnsLog.d("hello sessionId: " + sessionId);
     }
 
     public static String getSessionId() {