diff --git a/packages/backend/server/src/__tests__/models/user-doc.spec.ts b/packages/backend/server/src/__tests__/models/user-doc.spec.ts
new file mode 100644
index 0000000000..9e213c0ea8
--- /dev/null
+++ b/packages/backend/server/src/__tests__/models/user-doc.spec.ts
@@ -0,0 +1,96 @@
+import { randomUUID } from 'node:crypto';
+
+import ava, { TestFn } from 'ava';
+
+import { Config } from '../../base/config';
+import { type User, UserModel } from '../../models/user';
+import { UserDocModel } from '../../models/user-doc';
+import { createTestingModule, type TestingModule } from '../utils';
+
+interface Context {
+  config: Config;
+  module: TestingModule;
+  user: UserModel;
+  doc: UserDocModel;
+}
+
+const test = ava as TestFn<Context>;
+
+test.before(async t => {
+  const module = await createTestingModule();
+
+  t.context.user = module.get(UserModel);
+  t.context.doc = module.get(UserDocModel);
+  t.context.config = module.get(Config);
+  t.context.module = module;
+});
+
+let user: User;
+
+test.beforeEach(async t => {
+  await t.context.module.initTestingDB();
+  user = await t.context.user.create({
+    email: 'test@affine.pro',
+  });
+});
+
+test.after(async t => {
+  await t.context.module.close();
+});
+
+test('should upsert a doc', async t => {
+  const docId = randomUUID();
+  const doc = await t.context.doc.upsert({
+    spaceId: user.id,
+    docId,
+    blob: Buffer.from('hello'),
+    timestamp: Date.now(),
+    editorId: user.id,
+  });
+  t.truthy(doc.updatedAt);
+  // add a new one
+  const docId2 = randomUUID();
+  const doc2 = await t.context.doc.upsert({
+    spaceId: user.id,
+    docId: docId2,
+    blob: Buffer.from('world'),
+    timestamp: Date.now(),
+    editorId: user.id,
+  });
+  t.truthy(doc2.updatedAt);
+  // update the first one
+  const doc3 = await t.context.doc.upsert({
+    spaceId: user.id,
+    docId,
+    blob: Buffer.from('world'),
+    timestamp: Date.now() + 1000,
+    editorId: user.id,
+  });
+  t.truthy(doc3.updatedAt);
+  t.true(doc3.updatedAt > doc.updatedAt);
+  // get all docs timestamps
+  const timestamps = await t.context.doc.findTimestampsByUserId(user.id);
+  t.deepEqual(timestamps, {
+    [docId]: doc3.updatedAt.getTime(),
+    [docId2]: doc2.updatedAt.getTime(),
+  });
+});
+
+test('should get a doc', async t => {
+  const docId = randomUUID();
+  const doc = await t.context.doc.upsert({
+    spaceId: user.id,
+    docId,
+    blob: Buffer.from('hello'),
+    timestamp: Date.now(),
+    editorId: user.id,
+  });
+  t.truthy(doc.updatedAt);
+  const doc2 = await t.context.doc.get(user.id, docId);
+  t.truthy(doc2);
+  t.is(doc2!.docId, docId);
+  t.deepEqual(doc2!.blob, Buffer.from('hello'));
+  // get a non-exist doc
+  const doc3 = await t.context.doc.get(user.id, randomUUID());
+  t.is(doc3, null);
+});
diff --git a/packages/backend/server/src/models/index.ts b/packages/backend/server/src/models/index.ts
index 44067c03e5..745d652bbe 100644
--- a/packages/backend/server/src/models/index.ts
+++ b/packages/backend/server/src/models/index.ts
@@ -13,6 +13,7 @@ import { PageModel } from './page';
 import { MODELS_SYMBOL } from './provider';
 import { SessionModel } from './session';
 import { UserModel } from './user';
+import { UserDocModel } from './user-doc';
 import { UserFeatureModel } from './user-feature';
 import { VerificationTokenModel } from './verification-token';
 import { WorkspaceModel } from './workspace';
@@ -28,6 +29,7 @@ const MODELS = {
   userFeature: UserFeatureModel,
   workspaceFeature: WorkspaceFeatureModel,
   doc: DocModel,
+  userDoc: UserDocModel,
 };
 
 type ModelsType = {
@@ -85,6 +87,7 @@ export * from './feature';
 export * from './page';
 export * from './session';
 export * from './user';
+export * from './user-doc';
 export * from './user-feature';
 export * from './verification-token';
 export * from './workspace';
diff --git a/packages/backend/server/src/models/user-doc.ts b/packages/backend/server/src/models/user-doc.ts
new file mode 100644
index 0000000000..22e5e0adfb
--- /dev/null
+++ b/packages/backend/server/src/models/user-doc.ts
@@ -0,0 +1,116 @@
+import { Injectable } from '@nestjs/common';
+
+import { BaseModel } from './base';
+import { Doc } from './common';
+
+/**
+ * User Doc Model
+ */
+@Injectable()
+export class UserDocModel extends BaseModel {
+  async upsert(doc: Doc) {
+    const row = await this.db.userSnapshot.upsert({
+      where: {
+        userId_id: {
+          userId: doc.spaceId,
+          id: doc.docId,
+        },
+      },
+      update: {
+        blob: doc.blob,
+        updatedAt: new Date(doc.timestamp),
+      },
+      create: {
+        userId: doc.spaceId,
+        id: doc.docId,
+        blob: doc.blob,
+        createdAt: new Date(doc.timestamp),
+        updatedAt: new Date(doc.timestamp),
+      },
+      select: {
+        updatedAt: true,
+      },
+    });
+    return row;
+  }
+
+  async get(userId: string, docId: string): Promise<Doc | null> {
+    const row = await this.db.userSnapshot.findUnique({
+      where: {
+        userId_id: {
+          userId,
+          id: docId,
+        },
+      },
+    });
+
+    if (!row) {
+      return null;
+    }
+
+    return {
+      spaceId: row.userId,
+      docId: row.id,
+      blob: row.blob,
+      timestamp: row.updatedAt.getTime(),
+      editorId: row.userId,
+    };
+  }
+
+  /**
+   * Find the timestamps of user docs by userId.
+   *
+   * @param after Only return timestamps after this timestamp.
+   */
+  async findTimestampsByUserId(userId: string, after?: number) {
+    const snapshots = await this.db.userSnapshot.findMany({
+      select: {
+        id: true,
+        updatedAt: true,
+      },
+      where: {
+        userId,
+        ...(after
+          ? {
+              updatedAt: {
+                gt: new Date(after),
+              },
+            }
+          : {}),
+      },
+    });
+
+    const result: Record<string, number> = {};
+
+    snapshots.forEach(s => {
+      result[s.id] = s.updatedAt.getTime();
+    });
+    return result;
+  }
+
+  /**
+   * Delete a user doc by userId and docId.
+   */
+  async delete(userId: string, docId: string) {
+    await this.db.userSnapshot.deleteMany({
+      where: {
+        userId,
+        id: docId,
+      },
+    });
+    this.logger.log(`Deleted user ${userId} doc ${docId}`);
+  }
+
+  /**
+   * Delete all user docs by userId.
+   */
+  async deleteAllByUserId(userId: string) {
+    const { count } = await this.db.userSnapshot.deleteMany({
+      where: {
+        userId,
+      },
+    });
+    this.logger.log(`Deleted user ${userId} ${count} docs`);
+    return count;
+  }
+}