diff --git a/models/user.js b/models/user.js
index c67c475..d8db557 100644
--- a/models/user.js
+++ b/models/user.js
@@ -85,8 +85,9 @@ class User extends Model {
   async refreshSubmitInfo() {
     await syzoj.utils.lock(['User::refreshSubmitInfo', this.id], async () => {
       let JudgeState = syzoj.model('judge_state');
-      let all = await JudgeState.model.findAll({
-        attributes: ['problem_id'],
+      this.ac_num = await JudgeState.model.count({
+        col: 'problem_id',
+        distinct: true,
         where: {
           user_id: this.id,
           status: 'Accepted',
@@ -96,19 +97,13 @@ class User extends Model {
         }
       });
 
-      let s = new Set();
-      all.forEach(x => s.add(parseInt(x.get('problem_id'))));
-      this.ac_num = s.size;
-
-      let cnt = await JudgeState.count({
+      this.submit_num = await JudgeState.count({
         user_id: this.id,
         type: {
           $ne: 1 // Not a contest submission
         }
       });
 
-      this.submit_num = cnt;
-
       await this.save();
     });
   }
@@ -116,20 +111,19 @@ class User extends Model {
   async getACProblems() {
     let JudgeState = syzoj.model('judge_state');
 
-    let all = await JudgeState.model.findAll({
-      attributes: ['problem_id'],
+    let queryResult = await JudgeState.model.aggregate('problem_id', 'DISTINCT', {
+      plain: false,
       where: {
         user_id: this.id,
         status: 'Accepted',
         type: {
           $ne: 1 // Not a contest submissio
         }
-      }
+      },
+      order: [["problem_id", "ASC"]]
     });
 
-    let s = new Set();
-    all.forEach(x => s.add(parseInt(x.get('problem_id'))));
-    return Array.from(s).sort((a, b) => a - b);
+    return queryResult.map(record => record['DISTINCT'])
   }
 
   async getArticles() {