diff --git a/packages/backend/server/migrations/20240506051856_add_user_and_features_index/migration.sql b/packages/backend/server/migrations/20240506051856_add_user_and_features_index/migration.sql
new file mode 100644
index 0000000000..2e9b63c446
--- /dev/null
+++ b/packages/backend/server/migrations/20240506051856_add_user_and_features_index/migration.sql
@@ -0,0 +1,5 @@
+-- CreateIndex
+CREATE INDEX "user_features_user_id_idx" ON "user_features"("user_id");
+
+-- CreateIndex
+CREATE INDEX "users_email_idx" ON "users"("email");
diff --git a/packages/backend/server/schema.prisma b/packages/backend/server/schema.prisma
index 920268a1c1..f429304306 100644
--- a/packages/backend/server/schema.prisma
+++ b/packages/backend/server/schema.prisma
@@ -32,6 +32,7 @@ model User {
   sessions             UserSession[]
   aiSessions           AiSession[]
 
+  @@index([email])
   @@map("users")
 }
 
@@ -195,6 +196,7 @@ model UserFeatures {
   feature Features @relation(fields: [featureId], references: [id], onDelete: Cascade)
   user    User     @relation(fields: [userId], references: [id], onDelete: Cascade)
 
+  @@index([userId])
   @@map("user_features")
 }
 
diff --git a/packages/backend/server/src/core/features/management.ts b/packages/backend/server/src/core/features/management.ts
index b0c23bd2f3..3b34c279d3 100644
--- a/packages/backend/server/src/core/features/management.ts
+++ b/packages/backend/server/src/core/features/management.ts
@@ -138,19 +138,11 @@ export class FeatureManagementService {
   async addWorkspaceFeatures(
     workspaceId: string,
     feature: FeatureType,
-    version?: number,
     reason?: string
   ) {
-    const latestVersions = await this.feature.getFeaturesVersion();
-    // use latest version if not specified
-    const latestVersion = version || latestVersions[feature];
-    if (!Number.isInteger(latestVersion)) {
-      throw new Error(`Version of feature ${feature} not found`);
-    }
     return this.feature.addWorkspaceFeature(
       workspaceId,
       feature,
-      latestVersion,
       reason || 'add feature by api'
     );
   }
diff --git a/packages/backend/server/src/core/features/service.ts b/packages/backend/server/src/core/features/service.ts
index 4cb4a62da6..4c27a22d9c 100644
--- a/packages/backend/server/src/core/features/service.ts
+++ b/packages/backend/server/src/core/features/service.ts
@@ -8,33 +8,6 @@ import { FeatureKind, FeatureType } from './types';
 @Injectable()
 export class FeatureService {
   constructor(private readonly prisma: PrismaClient) {}
-
-  async getFeaturesVersion() {
-    const features = await this.prisma.features.findMany({
-      where: {
-        type: FeatureKind.Feature,
-      },
-      select: {
-        feature: true,
-        version: true,
-      },
-    });
-    return features.reduce(
-      (acc, feature) => {
-        // only keep the latest version
-        if (acc[feature.feature]) {
-          if (acc[feature.feature] < feature.version) {
-            acc[feature.feature] = feature.version;
-          }
-        } else {
-          acc[feature.feature] = feature.version;
-        }
-        return acc;
-      },
-      {} as Record<string, number>
-    );
-  }
-
   async getFeature<F extends FeatureType>(
     feature: F
   ): Promise<FeatureConfigType<F> | undefined> {
@@ -80,14 +53,15 @@ export class FeatureService {
       if (latestFlag) {
         return latestFlag.id;
       } else {
-        const latestVersion = await tx.features
-          .aggregate({
-            where: { feature },
-            _max: { version: true },
+        const featureId = await tx.features
+          .findFirst({
+            where: { feature, type: FeatureKind.Feature },
+            orderBy: { version: 'desc' },
+            select: { id: true },
           })
-          .then(r => r._max.version);
+          .then(r => r?.id);
 
-        if (!latestVersion) {
+        if (!featureId) {
           throw new Error(`Feature ${feature} not found`);
         }
 
@@ -97,20 +71,8 @@ export class FeatureService {
               reason,
               expiredAt,
               activated: true,
-              user: {
-                connect: {
-                  id: userId,
-                },
-              },
-              feature: {
-                connect: {
-                  feature_version: {
-                    feature,
-                    version: latestVersion,
-                  },
-                  type: FeatureKind.Feature,
-                },
-              },
+              userId,
+              featureId,
             },
           })
           .then(r => r.id);
@@ -144,10 +106,8 @@ export class FeatureService {
   async getUserFeatures(userId: string) {
     const features = await this.prisma.userFeatures.findMany({
       where: {
-        user: { id: userId },
-        feature: {
-          type: FeatureKind.Feature,
-        },
+        userId,
+        feature: { type: FeatureKind.Feature },
       },
       select: {
         activated: true,
@@ -171,7 +131,7 @@ export class FeatureService {
   async getActivatedUserFeatures(userId: string) {
     const features = await this.prisma.userFeatures.findMany({
       where: {
-        user: { id: userId },
+        userId,
         feature: { type: FeatureKind.Feature },
         activated: true,
         OR: [{ expiredAt: null }, { expiredAt: { gt: new Date() } }],
@@ -242,7 +202,6 @@ export class FeatureService {
   async addWorkspaceFeature(
     workspaceId: string,
     feature: FeatureType,
-    version: number,
     reason: string,
     expiredAt?: Date | string
   ) {
@@ -263,26 +222,27 @@ export class FeatureService {
       if (latestFlag) {
         return latestFlag.id;
       } else {
+        // use latest version of feature
+        const featureId = await tx.features
+          .findFirst({
+            where: { feature, type: FeatureKind.Feature },
+            select: { id: true },
+            orderBy: { version: 'desc' },
+          })
+          .then(r => r?.id);
+
+        if (!featureId) {
+          throw new Error(`Feature ${feature} not found`);
+        }
+
         return tx.workspaceFeatures
           .create({
             data: {
               reason,
               expiredAt,
               activated: true,
-              workspace: {
-                connect: {
-                  id: workspaceId,
-                },
-              },
-              feature: {
-                connect: {
-                  feature_version: {
-                    feature,
-                    version,
-                  },
-                  type: FeatureKind.Feature,
-                },
-              },
+              workspaceId,
+              featureId,
             },
           })
           .then(r => r.id);
diff --git a/packages/backend/server/src/core/quota/service.ts b/packages/backend/server/src/core/quota/service.ts
index b19a2729d1..7ad6464dd4 100644
--- a/packages/backend/server/src/core/quota/service.ts
+++ b/packages/backend/server/src/core/quota/service.ts
@@ -19,9 +19,7 @@ export class QuotaService {
   async getUserQuota(userId: string) {
     const quota = await this.prisma.userFeatures.findFirst({
       where: {
-        user: {
-          id: userId,
-        },
+        userId,
         feature: {
           type: FeatureKind.Quota,
         },
@@ -48,9 +46,7 @@ export class QuotaService {
   async getUserQuotas(userId: string) {
     const quotas = await this.prisma.userFeatures.findMany({
       where: {
-        user: {
-          id: userId,
-        },
+        userId,
         feature: {
           type: FeatureKind.Quota,
         },
@@ -96,14 +92,17 @@ export class QuotaService {
         return;
       }
 
-      const latestPlanVersion = await tx.features.aggregate({
-        where: {
-          feature: quota,
-        },
-        _max: {
-          version: true,
-        },
-      });
+      const featureId = await tx.features
+        .findFirst({
+          where: { feature: quota, type: FeatureKind.Quota },
+          select: { id: true },
+          orderBy: { version: 'desc' },
+        })
+        .then(f => f?.id);
+
+      if (!featureId) {
+        throw new Error(`Quota ${quota} not found`);
+      }
 
       // we will deactivate all exists quota for this user
       await tx.userFeatures.updateMany({
@@ -121,20 +120,8 @@ export class QuotaService {
 
       await tx.userFeatures.create({
         data: {
-          user: {
-            connect: {
-              id: userId,
-            },
-          },
-          feature: {
-            connect: {
-              feature_version: {
-                feature: quota,
-                version: latestPlanVersion._max.version || 1,
-              },
-              type: FeatureKind.Quota,
-            },
-          },
+          userId,
+          featureId,
           reason: reason ?? 'switch quota',
           activated: true,
           expiredAt,
diff --git a/packages/backend/server/src/core/workspaces/management.ts b/packages/backend/server/src/core/workspaces/management.ts
index e28932f970..942dc62df8 100644
--- a/packages/backend/server/src/core/workspaces/management.ts
+++ b/packages/backend/server/src/core/workspaces/management.ts
@@ -81,7 +81,6 @@ export class WorkspaceManagementResolver {
         .addWorkspaceFeatures(
           workspaceId,
           feature,
-          undefined,
           'add by experimental feature api'
         )
         .then(id => id > 0);
diff --git a/packages/backend/server/src/core/workspaces/resolvers/workspace.ts b/packages/backend/server/src/core/workspaces/resolvers/workspace.ts
index a16b2d9e68..9bf0bdbba3 100644
--- a/packages/backend/server/src/core/workspaces/resolvers/workspace.ts
+++ b/packages/backend/server/src/core/workspaces/resolvers/workspace.ts
@@ -218,11 +218,7 @@ export class WorkspaceResolver {
         permissions: {
           create: {
             type: Permission.Owner,
-            user: {
-              connect: {
-                id: user.id,
-              },
-            },
+            userId: user.id,
             accepted: true,
           },
         },
diff --git a/packages/backend/server/src/data/migrations/utils/user-features.ts b/packages/backend/server/src/data/migrations/utils/user-features.ts
index 35510e5547..fdc7c9130d 100644
--- a/packages/backend/server/src/data/migrations/utils/user-features.ts
+++ b/packages/backend/server/src/data/migrations/utils/user-features.ts
@@ -46,6 +46,16 @@ export async function upsertLatestFeatureVersion(
 
 export async function migrateNewFeatureTable(prisma: PrismaClient) {
   const waitingList = await prisma.newFeaturesWaitingList.findMany();
+  const latestEarlyAccessFeatureId = await prisma.features
+    .findFirst({
+      where: { feature: FeatureType.EarlyAccess, type: FeatureKind.Feature },
+      select: { id: true },
+      orderBy: { version: 'desc' },
+    })
+    .then(r => r?.id);
+  if (!latestEarlyAccessFeatureId) {
+    throw new Error('Feature EarlyAccess not found');
+  }
   for (const oldUser of waitingList) {
     const user = await prisma.user.findFirst({
       where: {
@@ -85,20 +95,8 @@ export async function migrateNewFeatureTable(prisma: PrismaClient) {
                 data: {
                   reason: 'Early access user',
                   activated: true,
-                  user: {
-                    connect: {
-                      id: user.id,
-                    },
-                  },
-                  feature: {
-                    connect: {
-                      feature_version: {
-                        feature: FeatureType.EarlyAccess,
-                        version: 1,
-                      },
-                      type: FeatureKind.Feature,
-                    },
-                  },
+                  userId: user.id,
+                  featureId: latestEarlyAccessFeatureId,
                 },
               })
               .then(r => r.id);
diff --git a/packages/backend/server/src/plugins/copilot/session.ts b/packages/backend/server/src/plugins/copilot/session.ts
index 92c1388bc5..d313e31a34 100644
--- a/packages/backend/server/src/plugins/copilot/session.ts
+++ b/packages/backend/server/src/plugins/copilot/session.ts
@@ -23,6 +23,7 @@ import {
 } from './types';
 
 export class ChatSession implements AsyncDisposable {
+  private stashMessageCount = 0;
   constructor(
     private readonly messageCache: ChatMessageCache,
     private readonly state: ChatSessionState,
@@ -46,6 +47,11 @@ export class ChatSession implements AsyncDisposable {
     return { sessionId, userId, workspaceId, docId, promptName };
   }
 
+  get stashMessages() {
+    if (!this.stashMessageCount) return [];
+    return this.state.messages.slice(-this.stashMessageCount);
+  }
+
   push(message: ChatMessage) {
     if (
       this.state.prompt.action &&
@@ -55,6 +61,7 @@ export class ChatSession implements AsyncDisposable {
       throw new Error('Action has been taken, no more messages allowed');
     }
     this.state.messages.push(message);
+    this.stashMessageCount += 1;
   }
 
   async getMessageById(messageId: string) {
@@ -141,7 +148,12 @@ export class ChatSession implements AsyncDisposable {
   }
 
   async save() {
-    await this.dispose?.(this.state);
+    await this.dispose?.({
+      ...this.state,
+      // only provide new messages
+      messages: this.stashMessages,
+    });
+    this.stashMessageCount = 0;
   }
 
   async [Symbol.asyncDispose]() {
@@ -181,36 +193,40 @@ export class ChatSessionService {
         if (id) sessionId = id;
       }
 
-      const messages = state.messages.map(m => ({
-        ...m,
-        attachments: m.attachments || undefined,
-        params: m.params || undefined,
-      }));
+      const haveSession = await tx.aiSession
+        .count({
+          where: {
+            id: sessionId,
+            userId: state.userId,
+          },
+        })
+        .then(c => c > 0);
 
-      await tx.aiSession.upsert({
-        where: {
-          id: sessionId,
-          userId: state.userId,
-        },
-        update: {
-          messages: {
-            // skip delete old messages if no new messages
-            deleteMany: messages.length ? {} : undefined,
-            create: messages,
+      if (haveSession) {
+        // message will only exists when setSession call by session.save
+        if (state.messages.length) {
+          await tx.aiSessionMessage.createMany({
+            data: state.messages.map(m => ({
+              ...m,
+              attachments: m.attachments || undefined,
+              params: m.params || undefined,
+              sessionId,
+            })),
+          });
+        }
+      } else {
+        await tx.aiSession.create({
+          data: {
+            id: sessionId,
+            workspaceId: state.workspaceId,
+            docId: state.docId,
+            // connect
+            userId: state.userId,
+            promptName: state.prompt.name,
           },
-        },
-        create: {
-          id: sessionId,
-          workspaceId: state.workspaceId,
-          docId: state.docId,
-          messages: {
-            create: messages,
-          },
-          // connect
-          user: { connect: { id: state.userId } },
-          prompt: { connect: { name: state.prompt.name } },
-        },
-      });
+        });
+      }
+
       return sessionId;
     });
   }
diff --git a/packages/backend/server/tests/copilot.spec.ts b/packages/backend/server/tests/copilot.spec.ts
index 40f4bae9ec..f9976e8b17 100644
--- a/packages/backend/server/tests/copilot.spec.ts
+++ b/packages/backend/server/tests/copilot.spec.ts
@@ -336,6 +336,32 @@ test('should be able to generate with message id', async t => {
   }
 });
 
+test('should save message correctly', async t => {
+  const { prompt, session } = t.context;
+
+  await prompt.set('prompt', 'model', [
+    { role: 'system', content: 'hello {{word}}' },
+  ]);
+
+  const sessionId = await session.create({
+    docId: 'test',
+    workspaceId: 'test',
+    userId,
+    promptName: 'prompt',
+  });
+  const s = (await session.get(sessionId))!;
+
+  const message = (await session.createMessage({
+    sessionId,
+    content: 'hello',
+  }))!;
+
+  await s.pushByMessageId(message);
+  t.is(s.stashMessages.length, 1, 'should get stash messages');
+  await s.save();
+  t.is(s.stashMessages.length, 0, 'should empty stash messages after save');
+});
+
 // ==================== provider ====================
 
 test('should be able to get provider', async t => {
diff --git a/packages/backend/server/tests/feature.spec.ts b/packages/backend/server/tests/feature.spec.ts
index 52be2609fc..d8e19bc32b 100644
--- a/packages/backend/server/tests/feature.spec.ts
+++ b/packages/backend/server/tests/feature.spec.ts
@@ -29,11 +29,7 @@ class WorkspaceResolverMock {
         permissions: {
           create: {
             type: Permission.Owner,
-            user: {
-              connect: {
-                id: user.id,
-              },
-            },
+            userId: user.id,
             accepted: true,
           },
         },
@@ -163,7 +159,7 @@ test('should be able to set workspace feature', async t => {
   const f1 = await feature.getWorkspaceFeatures(w1.id);
   t.is(f1.length, 0, 'should be empty');
 
-  await feature.addWorkspaceFeature(w1.id, FeatureType.Copilot, 1, 'test');
+  await feature.addWorkspaceFeature(w1.id, FeatureType.Copilot, 'test');
 
   const f2 = await feature.getWorkspaceFeatures(w1.id);
   t.is(f2.length, 1, 'should have 1 feature');
@@ -178,7 +174,7 @@ test('should be able to check workspace feature', async t => {
   const f1 = await management.hasWorkspaceFeature(w1.id, FeatureType.Copilot);
   t.false(f1, 'should not have copilot');
 
-  await management.addWorkspaceFeatures(w1.id, FeatureType.Copilot, 1, 'test');
+  await management.addWorkspaceFeatures(w1.id, FeatureType.Copilot, 'test');
   const f2 = await management.hasWorkspaceFeature(w1.id, FeatureType.Copilot);
   t.true(f2, 'should have copilot');
 
@@ -195,7 +191,7 @@ test('should be able revert workspace feature', async t => {
   const f1 = await management.hasWorkspaceFeature(w1.id, FeatureType.Copilot);
   t.false(f1, 'should not have feature');
 
-  await management.addWorkspaceFeatures(w1.id, FeatureType.Copilot, 1, 'test');
+  await management.addWorkspaceFeatures(w1.id, FeatureType.Copilot, 'test');
   const f2 = await management.hasWorkspaceFeature(w1.id, FeatureType.Copilot);
   t.true(f2, 'should have feature');
 
diff --git a/tests/kit/utils/cloud.ts b/tests/kit/utils/cloud.ts
index 683e941986..c61b9cd565 100644
--- a/tests/kit/utils/cloud.ts
+++ b/tests/kit/utils/cloud.ts
@@ -97,6 +97,14 @@ export async function createRandomUser(): Promise<{
     password: '123456',
   };
   const result = await runPrisma(async client => {
+    const featureId = await client.features
+      .findFirst({
+        where: { feature: 'free_plan_v1' },
+        select: { id: true },
+        orderBy: { version: 'desc' },
+      })
+      .then(f => f!.id);
+
     await client.user.create({
       data: {
         ...user,
@@ -106,14 +114,7 @@ export async function createRandomUser(): Promise<{
           create: {
             reason: 'created by test case',
             activated: true,
-            feature: {
-              connect: {
-                feature_version: {
-                  feature: 'free_plan_v1',
-                  version: 1,
-                },
-              },
-            },
+            featureId,
           },
         },
       },