diff --git a/.travis.yml b/.travis.yml
index 8622616d..0ef835b3 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,12 +2,27 @@ language: python
 
 dist: xenial  # required for Python >= 3.7 (travis-ci/travis-ci#9069)
 
+cache: pip
+
+git:
+  depth: 1
+
 python:
   - "3.7"
 
+services:
+  - mongodb
+  - mysql
+  - postgresql
+
+before_script:
+  - psql -d postgresql://postgres:${VNPY_TEST_POSTGRESQL_PASSWORD}@localhost -c "create database vnpy;"
+  - mysql -u root --password=${VNPY_TEST_MYSQL_PASSWORD} -e 'CREATE DATABASE vnpy;'
+
 script:
-  # todo: use python unittest
-  - mkdir run; cd run; python ../tests/load_all.py
+  - pip install psycopg2 mongoengine pymysql  # we should support all database in test environment
+  - cd tests; source travis_env.sh;
+  - python test_all.py
 
 matrix:
   include:
@@ -19,81 +34,36 @@ matrix:
       script:
         - flake8
 
-    - name: "pip install under Windows"
-      os: "windows"
-      # language : cpp is necessary for windows
-      language: "cpp"
-      env:
-        - PATH=/c/Python37:/c/Python37/Scripts:$PATH
-      before_install:
-        - choco install python3 --version 3.7.2
-      install:
-        - python -m pip install --upgrade pip wheel setuptools
-        - pip install https://pip.vnpy.com/colletion/TA_Lib-0.4.17-cp37-cp37m-win_amd64.whl
-        - pip install https://pip.vnpy.com/colletion/ibapi-9.75.1-001-py3-none-any.whl
-        - pip install -r requirements.txt
-        - pip install .
-
     - name: "pip install under Ubuntu: gcc-8"
+      addons:
+        apt:
+          sources:
+            - ubuntu-toolchain-r-test
+          packages:
+            - g++-8
       before_install:
-        # C++17
-        - sudo add-apt-repository -y ppa:ubuntu-toolchain-r/test
-        - sudo apt-get update -y
-      install:
-        # C++17
-        - sudo apt-get install -y gcc-8 g++-8
         - sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-8 90
         - sudo update-alternatives --install /usr/bin/c++ c++ /usr/bin/g++-8 90
         - sudo update-alternatives --install /usr/bin/gcc cc /usr/bin/gcc-8 90
+      install:
         # update pip & setuptools
         - python -m pip install --upgrade pip wheel setuptools
         # Linux install script
         - pip install https://pip.vnpy.com/colletion/ibapi-9.75.1-001-py3-none-any.whl
         - bash ./install.sh
 
-    - name: "pip install under Ubuntu: gcc-7"
+    - name: "sdist install under Ubuntu: gcc-7"
+      addons:
+        apt:
+          sources:
+            - ubuntu-toolchain-r-test
+          packages:
+            - g++-7
       before_install:
-        # C++17
-        - sudo add-apt-repository -y ppa:ubuntu-toolchain-r/test
-        - sudo apt-get update -y
-      install:
-        # C++17
-        - sudo apt-get install -y gcc-7 g++-7
         - sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-7 90
         - sudo update-alternatives --install /usr/bin/c++ c++ /usr/bin/g++-7 90
         - sudo update-alternatives --install /usr/bin/gcc cc /usr/bin/gcc-7 90
-        # update pip & setuptools
-        - python -m pip install --upgrade pip wheel setuptools
-        # Linux install script
-        - pip install https://pip.vnpy.com/colletion/ibapi-9.75.1-001-py3-none-any.whl
-        - bash ./install.sh
-
-    - name: "sdist install under Windows"
-      os: "windows"
-      # language : cpp is necessary for windows
-      language: "cpp"
-      env:
-        - PATH=/c/Python37:/c/Python37/Scripts:$PATH
-      before_install:
-        - choco install python3 --version 3.7.2
       install:
-        - python -m pip install --upgrade pip wheel setuptools
-        - python setup.py sdist
-        - pip install https://pip.vnpy.com/colletion/TA_Lib-0.4.17-cp37-cp37m-win_amd64.whl
-        - pip install https://pip.vnpy.com/colletion/ibapi-9.75.1-001-py3-none-any.whl
-        - pip install dist/`ls dist`
-
-    - name: "sdist install under Ubuntu: gcc-8"
-      before_install:
-        # C++17
-        - sudo add-apt-repository -y ppa:ubuntu-toolchain-r/test
-        - sudo apt-get update -y
-      install:
-        # C++17
-        - sudo apt-get install -y gcc-8 g++-8
-        - sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-8 90
-        - sudo update-alternatives --install /usr/bin/c++ c++ /usr/bin/g++-8 90
-        - sudo update-alternatives --install /usr/bin/gcc cc /usr/bin/gcc-8 90
         # Linux install script
         - python -m pip install --upgrade pip wheel setuptools
         - pushd /tmp
@@ -108,3 +78,17 @@ matrix:
         - pip install https://pip.vnpy.com/colletion/ibapi-9.75.1-001-py3-none-any.whl
         - python setup.py sdist
         - pip install dist/`ls dist`
+
+    - name: "pip install under osx"
+      os: osx
+      language: shell  # osx supports only shell
+      services: []
+      before_install: []
+      install:
+        - pip3 install https://pip.vnpy.com/colletion/ibapi-9.75.1-001-py3-none-any.whl
+        - bash ./install_osx.sh
+      before_script: []
+      script:
+        - pip3 install psycopg2 mongoengine pymysql  # we should support all database in test environment
+        - cd tests; source travis_env.sh;
+        - VNPY_TEST_ONLY_SQLITE=1 python3 test_all.py
diff --git a/appveyor.yml b/appveyor.yml
new file mode 100644
index 00000000..437edefc
--- /dev/null
+++ b/appveyor.yml
@@ -0,0 +1,68 @@
+clone_depth: 1
+
+cache:
+  - '%LOCALAPPDATA%\pip\Cache'
+
+configuration:
+  - pip
+  - sdist
+
+image:
+  - Visual Studio 2017
+
+services:
+  - mysql
+  - mongodb
+  - postgresql
+
+environment:
+  PATH: C:\Python37-x64;C:\Python37-x64\Scripts;C:\Program Files\PostgreSQL\9.6\bin\;%PATH%
+  VNPY_TEST_MYSQL_DATABASE: vnpy
+  VNPY_TEST_MYSQL_HOST: localhost
+  VNPY_TEST_MYSQL_PORT: 3306
+  VNPY_TEST_MYSQL_USER: root
+  VNPY_TEST_MYSQL_PASSWORD: Password12!
+
+  VNPY_TEST_POSTGRESQL_DATABASE: vnpy
+  VNPY_TEST_POSTGRESQL_HOST: localhost
+  VNPY_TEST_POSTGRESQL_PORT: 5432
+  VNPY_TEST_POSTGRESQL_USER: postgres
+  VNPY_TEST_POSTGRESQL_PASSWORD: Password12!
+
+  VNPY_TEST_MONGODB_DATABASE: vnpy
+  VNPY_TEST_MONGODB_HOST: localhost
+  VNPY_TEST_MONGODB_PORT: 27017
+
+  MYSQL_PWD: Password12!
+
+install:
+  - python -m pip install --upgrade pip wheel setuptools
+before_build:
+  - ps: psql -d "postgresql://${ENV:VNPY_TEST_POSTGRESQL_USER}:${ENV:VNPY_TEST_POSTGRESQL_PASSWORD}@localhost" -c "create database vnpy;"
+  - ps: . "C:\Program Files\MySQL\MySQL Server 5.7\bin\mysql" -u $ENV:VNPY_TEST_MYSQL_USER -e 'CREATE DATABASE vnpy;'
+
+for:
+  - matrix:
+      only:
+        - configuration: pip
+    build_script:
+      - pip install psycopg2 mongoengine pymysql  # we should support all database in test environment
+      - pip install https://pip.vnpy.com/colletion/TA_Lib-0.4.17-cp37-cp37m-win_amd64.whl
+      - pip install https://pip.vnpy.com/colletion/ibapi-9.75.1-001-py3-none-any.whl
+      - pip install -r requirements.txt
+      - pip install .
+
+  - matrix:
+      only:
+        - configuration: sdist
+    build_script:
+      - python setup.py sdist
+      - pip install psycopg2 mongoengine pymysql  # we should support all database in test environment
+      - pip install https://pip.vnpy.com/colletion/TA_Lib-0.4.17-cp37-cp37m-win_amd64.whl
+      - pip install https://pip.vnpy.com/colletion/ibapi-9.75.1-001-py3-none-any.whl
+      - ps: $name=(ls dist).name; pip install "dist/$name"
+
+test_script:
+  - cd tests
+  - python test_all.py
+
diff --git a/install.sh b/install.sh
index 2cf2043c..dc748ee5 100644
--- a/install.sh
+++ b/install.sh
@@ -1,27 +1,35 @@
 #!/usr/bin/env bash
 
+python=$1
+pip=$2
+prefix=$3
+
+[[ -z $python ]] && python=python
+[[ -z $pip ]] && pip=pip
+[[ -z $prefix ]] && prefix=/usr
+
 # Get and build ta-lib
 pushd /tmp
 wget http://prdownloads.sourceforge.net/ta-lib/ta-lib-0.4.0-src.tar.gz
 tar -xf ta-lib-0.4.0-src.tar.gz
 cd ta-lib
-./configure --prefix=/usr
-make
+./configure --prefix=$prefix
+make -j
 sudo make install
 popd
 
 # old versions of ta-lib imports numpy in setup.py
-pip install numpy
+$pip install numpy
 
 # Install extra packages
-pip install ta-lib
-pip install https://vnpy-pip.oss-cn-shanghai.aliyuncs.com/colletion/ibapi-9.75.1-py3-none-any.whl
+$pip install ta-lib
+$pip install https://vnpy-pip.oss-cn-shanghai.aliyuncs.com/colletion/ibapi-9.75.1-py3-none-any.whl
 
 # Install Python Modules
-pip install -r requirements.txt
+$pip install -r requirements.txt
 
 # Install local Chinese language environment
 sudo locale-gen zh_CN.GB18030
 
 # Install vn.py
-pip install .
\ No newline at end of file
+$pip install .
\ No newline at end of file
diff --git a/install_osx.sh b/install_osx.sh
new file mode 100644
index 00000000..eb96cc53
--- /dev/null
+++ b/install_osx.sh
@@ -0,0 +1,3 @@
+#!/usr/bin/env bash
+
+bash ./install.sh python3 pip3 /usr/local
\ No newline at end of file
diff --git a/setup.py b/setup.py
index 28250618..3b0d1ca7 100644
--- a/setup.py
+++ b/setup.py
@@ -29,70 +29,79 @@ with open("vnpy/__init__.py", "rb") as f:
     version = str(ast.literal_eval(version_line))
 
 if platform.uname().system == "Windows":
-    compiler_flags = ["/MP", "/std:c++17",  # standard
-                      "/O2", "/Ob2", "/Oi", "/Ot", "/Oy", "/GL",  # Optimization
-                      "/wd4819"  # 936 code page
-                      ]
+    compiler_flags = [
+        "/MP", "/std:c++17",  # standard
+        "/O2", "/Ob2", "/Oi", "/Ot", "/Oy", "/GL",  # Optimization
+        "/wd4819"  # 936 code page
+    ]
     extra_link_args = []
 else:
-    compiler_flags = ["-std=c++17",
-                      "-Wno-delete-incomplete", "-Wno-sign-compare",
-                      ]
+    compiler_flags = [
+        "-std=c++17",  # standard
+        "-O3",  # Optimization
+        "-Wno-delete-incomplete", "-Wno-sign-compare",
+    ]
     extra_link_args = ["-lstdc++"]
 
-vnctpmd = Extension("vnpy.api.ctp.vnctpmd",
-                    [
-                        "vnpy/api/ctp/vnctp/vnctpmd/vnctpmd.cpp",
-                    ],
-                    include_dirs=["vnpy/api/ctp/include",
-                                  "vnpy/api/ctp/vnctp", ],
-                    define_macros=[],
-                    undef_macros=[],
-                    library_dirs=["vnpy/api/ctp/libs", "vnpy/api/ctp"],
-                    libraries=["thostmduserapi", "thosttraderapi", ],
-                    extra_compile_args=compiler_flags,
-                    extra_link_args=extra_link_args,
-                    depends=[],
-                    runtime_library_dirs=["$ORIGIN"],
-                    language="cpp",
-                    )
-vnctptd = Extension("vnpy.api.ctp.vnctptd",
-                    [
-                        "vnpy/api/ctp/vnctp/vnctptd/vnctptd.cpp",
-                    ],
-                    include_dirs=["vnpy/api/ctp/include",
-                                  "vnpy/api/ctp/vnctp", ],
-                    define_macros=[],
-                    undef_macros=[],
-                    library_dirs=["vnpy/api/ctp/libs", "vnpy/api/ctp"],
-                    libraries=["thostmduserapi", "thosttraderapi", ],
-                    extra_compile_args=compiler_flags,
-                    extra_link_args=extra_link_args,
-                    runtime_library_dirs=["$ORIGIN"],
-                    depends=[],
-                    language="cpp",
-                    )
-vnoes = Extension("vnpy.api.oes.vnoes",
-                  [
-                      "vnpy/api/oes/vnoes/generated_files/classes_1.cpp",
-                      "vnpy/api/oes/vnoes/generated_files/classes_2.cpp",
-                      "vnpy/api/oes/vnoes/generated_files/module.cpp",
-                  ],
-                  include_dirs=["vnpy/api/oes/include",
-                                "vnpy/api/oes/vnoes", ],
-                  define_macros=[("BRIGAND_NO_BOOST_SUPPORT", "1")],
-                  undef_macros=[],
-                  library_dirs=["vnpy/api/oes/libs"],
-                  libraries=["oes_api"],
-                  extra_compile_args=compiler_flags,
-                  extra_link_args=extra_link_args,
-                  depends=[],
-                  language="cpp",
-                  )
+vnctpmd = Extension(
+    "vnpy.api.ctp.vnctpmd",
+    [
+        "vnpy/api/ctp/vnctp/vnctpmd/vnctpmd.cpp",
+    ],
+    include_dirs=["vnpy/api/ctp/include",
+                  "vnpy/api/ctp/vnctp", ],
+    define_macros=[],
+    undef_macros=[],
+    library_dirs=["vnpy/api/ctp/libs", "vnpy/api/ctp"],
+    libraries=["thostmduserapi", "thosttraderapi", ],
+    extra_compile_args=compiler_flags,
+    extra_link_args=extra_link_args,
+    depends=[],
+    runtime_library_dirs=["$ORIGIN"],
+    language="cpp",
+)
+vnctptd = Extension(
+    "vnpy.api.ctp.vnctptd",
+    [
+        "vnpy/api/ctp/vnctp/vnctptd/vnctptd.cpp",
+    ],
+    include_dirs=["vnpy/api/ctp/include",
+                  "vnpy/api/ctp/vnctp", ],
+    define_macros=[],
+    undef_macros=[],
+    library_dirs=["vnpy/api/ctp/libs", "vnpy/api/ctp"],
+    libraries=["thostmduserapi", "thosttraderapi", ],
+    extra_compile_args=compiler_flags,
+    extra_link_args=extra_link_args,
+    runtime_library_dirs=["$ORIGIN"],
+    depends=[],
+    language="cpp",
+)
+vnoes = Extension(
+    "vnpy.api.oes.vnoes",
+    [
+        "vnpy/api/oes/vnoes/generated_files/classes_1.cpp",
+        "vnpy/api/oes/vnoes/generated_files/classes_2.cpp",
+        "vnpy/api/oes/vnoes/generated_files/module.cpp",
+    ],
+    include_dirs=["vnpy/api/oes/include",
+                  "vnpy/api/oes/vnoes", ],
+    define_macros=[("BRIGAND_NO_BOOST_SUPPORT", "1")],
+    undef_macros=[],
+    library_dirs=["vnpy/api/oes/libs"],
+    libraries=["oes_api"],
+    extra_compile_args=compiler_flags,
+    extra_link_args=extra_link_args,
+    runtime_library_dirs=["$ORIGIN"],
+    depends=[],
+    language="cpp",
+)
 
-if platform.uname().system == "Windows":
+if platform.system() == "Windows":
     # use pre-built pyd for windows ( support python 3.7 only )
     ext_modules = []
+elif platform.system() == "Darwin":
+    ext_modules = []
 else:
     ext_modules = [vnctptd, vnctpmd, vnoes]
 
diff --git a/tests/app/__init__.py b/tests/app/__init__.py
new file mode 100644
index 00000000..9aafa67d
--- /dev/null
+++ b/tests/app/__init__.py
@@ -0,0 +1 @@
+from .test_csv_loader import *
diff --git a/tests/app/test_csv_loader.py b/tests/app/test_csv_loader.py
new file mode 100644
index 00000000..b52a2183
--- /dev/null
+++ b/tests/app/test_csv_loader.py
@@ -0,0 +1,90 @@
+"""
+Test if csv loader works fine
+"""
+import tempfile
+import unittest
+
+from vnpy.app.csv_loader import CsvLoaderEngine
+from vnpy.trader.constant import Exchange, Interval
+
+
+class TestCsvLoader(unittest.TestCase):
+
+    def setUp(self) -> None:
+        self.engine = CsvLoaderEngine(None, None)  # no engine is necessary for CsvLoader
+
+    def test_load(self):
+        data = """"Datetime","Open","High","Low","Close","Volume"
+2010-04-16 09:16:00,3450.0,3488.0,3450.0,3468.0,489
+2010-04-16 09:17:00,3468.0,3473.8,3467.0,3467.0,302
+2010-04-16 09:18:00,3467.0,3471.0,3466.0,3467.0,203
+2010-04-16 09:19:00,3467.0,3468.2,3448.0,3448.0,280
+2010-04-16 09:20:00,3448.0,3459.0,3448.0,3454.0,250
+2010-04-16 09:21:00,3454.0,3456.8,3454.0,3456.8,109
+"""
+        with tempfile.TemporaryFile("w+t") as f:
+            f.write(data)
+            f.seek(0)
+
+            self.engine.load_by_handle(
+                f,
+                symbol="1",
+                exchange=Exchange.BITMEX,
+                interval=Interval.MINUTE,
+                datetime_head="Datetime",
+                open_head="Open",
+                close_head="Close",
+                low_head="Low",
+                high_head="High",
+                volume_head="Volume",
+                datetime_format="%Y-%m-%d %H:%M:%S",
+            )
+
+    def test_load_duplicated(self):
+        data = """"Datetime","Open","High","Low","Close","Volume"
+2010-04-16 09:16:00,3450.0,3488.0,3450.0,3468.0,489
+2010-04-16 09:17:00,3468.0,3473.8,3467.0,3467.0,302
+2010-04-16 09:18:00,3467.0,3471.0,3466.0,3467.0,203
+2010-04-16 09:19:00,3467.0,3468.2,3448.0,3448.0,280
+2010-04-16 09:20:00,3448.0,3459.0,3448.0,3454.0,250
+2010-04-16 09:21:00,3454.0,3456.8,3454.0,3456.8,109
+"""
+        with tempfile.TemporaryFile("w+t") as f:
+            f.write(data)
+            f.seek(0)
+
+            self.engine.load_by_handle(
+                f,
+                symbol="1",
+                exchange=Exchange.BITMEX,
+                interval=Interval.MINUTE,
+                datetime_head="Datetime",
+                open_head="Open",
+                close_head="Close",
+                low_head="Low",
+                high_head="High",
+                volume_head="Volume",
+                datetime_format="%Y-%m-%d %H:%M:%S",
+            )
+
+        with tempfile.TemporaryFile("w+t") as f:
+            f.write(data)
+            f.seek(0)
+
+            self.engine.load_by_handle(
+                f,
+                symbol="1",
+                exchange=Exchange.BITMEX,
+                interval=Interval.MINUTE,
+                datetime_head="Datetime",
+                open_head="Open",
+                close_head="Close",
+                low_head="Low",
+                high_head="High",
+                volume_head="Volume",
+                datetime_format="%Y-%m-%d %H:%M:%S",
+            )
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/tests/backtesting/getdata.py b/tests/backtesting/getdata.py
index 77436bcc..62d02465 100644
--- a/tests/backtesting/getdata.py
+++ b/tests/backtesting/getdata.py
@@ -2,7 +2,7 @@ from time import time
 
 import rqdatac as rq
 
-from vnpy.trader.database import DbBarData, DB
+from vnpy.trader.database import DbBarData
 
 USERNAME = ""
 PASSWORD = ""
@@ -39,11 +39,11 @@ def download_minute_bar(vt_symbol):
 
     df = rq.get_price(symbol, frequency="1m", fields=FIELDS)
 
-    with DB.atomic():
-        for ix, row in df.iterrows():
-            print(row.name)
-            bar = generate_bar_from_row(row, symbol, exchange)
-            DbBarData.replace(bar.__data__).execute()
+    bars = []
+    for ix, row in df.iterrows():
+        bar = generate_bar_from_row(row, symbol, exchange)
+        bars.append(bar)
+    DbBarData.save_all(bars)
 
     end = time()
     cost = (end - start) * 1000
diff --git a/tests/test_all.py b/tests/test_all.py
new file mode 100644
index 00000000..59b7683e
--- /dev/null
+++ b/tests/test_all.py
@@ -0,0 +1,31 @@
+# tests/runner.py
+import unittest
+
+import app
+# import your test modules
+import test_import_all
+import trader
+
+# initialize the test suite
+loader = unittest.TestLoader()
+suite = unittest.TestSuite()
+
+# add tests to the test suite
+suite.addTests(loader.loadTestsFromModule(test_import_all))
+suite.addTests(loader.loadTestsFromModule(trader))
+suite.addTests(loader.loadTestsFromModule(app))
+
+
+# initialize a runner, pass it your suite and run it
+def main():
+    runner = unittest.TextTestRunner(verbosity=3)
+    result = runner.run(suite)
+    return result
+
+
+if __name__ == '__main__':
+    result = main()
+    if result.failures or result.errors:
+        exit(1)
+    else:
+        exit(0)
diff --git a/tests/load_all.py b/tests/test_import_all.py
similarity index 54%
rename from tests/load_all.py
rename to tests/test_import_all.py
index feae9c12..38d240f8 100644
--- a/tests/load_all.py
+++ b/tests/test_import_all.py
@@ -1,24 +1,45 @@
 # flake8: noqa
 import unittest
+import platform
 
 
+# noinspection PyUnresolvedReferences
 class ImportTest(unittest.TestCase):
 
     # noinspection PyUnresolvedReferences
     def test_import_all(self):
         from vnpy.event import EventEngine
 
+    def test_import_main_engine(self):
         from vnpy.trader.engine import MainEngine
+
+    def test_import_ui(self):
         from vnpy.trader.ui import MainWindow, create_qapp
 
+    def test_import_bitmex_gateway(self):
         from vnpy.gateway.bitmex import BitmexGateway
+
+    def test_import_futu_gateway(self):
         from vnpy.gateway.futu import FutuGateway
+
+    def test_import_ib_gateway(self):
         from vnpy.gateway.ib import IbGateway
+
+    @unittest.skipIf(platform.system() == "Darwin", "Not supported yet under osx")
+    def test_import_ctp_gateway(self):
         from vnpy.gateway.ctp import CtpGateway
+
+    def test_import_tiger_gateway(self):
         from vnpy.gateway.tiger import TigerGateway
+
+    @unittest.skipIf(platform.system() == "Darwin", "Not supported yet under osx")
+    def test_import_oes_gateway(self):
         from vnpy.gateway.oes import OesGateway
 
+    def test_import_cta_strategy_app(self):
         from vnpy.app.cta_strategy import CtaStrategyApp
+
+    def test_import_csv_loader_app(self):
         from vnpy.app.csv_loader import CsvLoaderApp
 
 
diff --git a/tests/trader/__init__.py b/tests/trader/__init__.py
new file mode 100644
index 00000000..c5776fc1
--- /dev/null
+++ b/tests/trader/__init__.py
@@ -0,0 +1,2 @@
+from .test_database import *
+from .test_settings import *
diff --git a/tests/trader/test_database.py b/tests/trader/test_database.py
new file mode 100644
index 00000000..df009baf
--- /dev/null
+++ b/tests/trader/test_database.py
@@ -0,0 +1,128 @@
+"""
+Test if database works fine
+"""
+import os
+import unittest
+from datetime import datetime, timedelta
+
+from vnpy.trader.constant import Exchange, Interval
+from vnpy.trader.database.database import Driver
+from vnpy.trader.object import BarData, TickData
+
+os.environ['VNPY_TESTING'] = '1'
+
+profiles = {
+    Driver.SQLITE: {
+        "driver": "sqlite",
+        "database": "test_db.db",
+    }
+}
+if 'VNPY_TEST_ONLY_SQLITE' not in os.environ:
+    profiles.update({
+        Driver.MYSQL: {
+            "driver": "mysql",
+            "database": os.environ['VNPY_TEST_MYSQL_DATABASE'],
+            "host": os.environ['VNPY_TEST_MYSQL_HOST'],
+            "port": int(os.environ['VNPY_TEST_MYSQL_PORT']),
+            "user": os.environ["VNPY_TEST_MYSQL_USER"],
+            "password": os.environ['VNPY_TEST_MYSQL_PASSWORD'],
+        },
+        Driver.POSTGRESQL: {
+            "driver": "postgresql",
+            "database": os.environ['VNPY_TEST_POSTGRESQL_DATABASE'],
+            "host": os.environ['VNPY_TEST_POSTGRESQL_HOST'],
+            "port": int(os.environ['VNPY_TEST_POSTGRESQL_PORT']),
+            "user": os.environ["VNPY_TEST_POSTGRESQL_USER"],
+            "password": os.environ['VNPY_TEST_POSTGRESQL_PASSWORD'],
+        },
+        Driver.MONGODB: {
+            "driver": "mongodb",
+            "database": os.environ['VNPY_TEST_MONGODB_DATABASE'],
+            "host": os.environ['VNPY_TEST_MONGODB_HOST'],
+            "port": int(os.environ['VNPY_TEST_MONGODB_PORT']),
+            "user": "",
+            "password": "",
+            "authentication_source": "",
+        },
+    })
+
+
+def now():
+    return datetime.utcnow()
+
+
+bar = BarData(
+    gateway_name="DB",
+    symbol="test_symbol",
+    exchange=Exchange.BITMEX,
+    datetime=now(),
+    interval=Interval.MINUTE,
+)
+
+tick = TickData(
+    gateway_name="DB",
+    symbol="test_symbol",
+    exchange=Exchange.BITMEX,
+    datetime=now(),
+    name="DB_test_symbol",
+)
+
+
+class TestDatabase(unittest.TestCase):
+
+    def connect(self, settings: dict):
+        from vnpy.trader.database.initialize import init  # noqa
+        self.manager = init(settings)
+
+    def test_upsert_bar(self):
+        for driver, settings in profiles.items():
+            with self.subTest(driver=driver, settings=settings):
+                self.connect(settings)
+                self.manager.save_bar_data([bar])
+                self.manager.save_bar_data([bar])
+
+    def test_save_load_bar(self):
+        for driver, settings in profiles.items():
+            with self.subTest(driver=driver, settings=settings):
+                self.connect(settings)
+                # save first
+                self.manager.save_bar_data([bar])
+
+                # and load
+                results = self.manager.load_bar_data(
+                    symbol=bar.symbol,
+                    exchange=bar.exchange,
+                    interval=bar.interval,
+                    start=bar.datetime - timedelta(seconds=1),  # time is not accuracy
+                    end=now() + timedelta(seconds=1),  # time is not accuracy
+                )
+                count = len(results)
+                self.assertNotEqual(count, 0)
+
+    def test_upsert_tick(self):
+        for driver, settings in profiles.items():
+            with self.subTest(driver=driver, settings=settings):
+                self.connect(settings)
+                self.manager.save_tick_data([tick])
+                self.manager.save_tick_data([tick])
+
+    def test_save_load_tick(self):
+        for driver, settings in profiles.items():
+            with self.subTest(driver=driver, settings=settings):
+                self.connect(settings)
+                # save first
+                self.manager.save_tick_data([tick])
+
+                # and load
+                results = self.manager.load_tick_data(
+                    symbol=bar.symbol,
+                    exchange=bar.exchange,
+                    start=bar.datetime - timedelta(seconds=1),  # time is not accuracy
+                    end=now() + timedelta(seconds=1),  # time is not accuracy
+                )
+                count = len(results)
+                self.assertNotEqual(count, 0)
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/tests/trader/test_settings.py b/tests/trader/test_settings.py
new file mode 100644
index 00000000..2d46e73e
--- /dev/null
+++ b/tests/trader/test_settings.py
@@ -0,0 +1,25 @@
+"""
+Test if database works fine
+"""
+import unittest
+
+from vnpy.trader.setting import SETTINGS, get_settings
+
+
+class TestSettings(unittest.TestCase):
+
+    def test_get_settings(self):
+        SETTINGS['a'] = 1
+        got = get_settings()
+        self.assertIn('a', got)
+        self.assertEqual(got['a'], 1)
+
+    def test_get_settings_with_prefix(self):
+        SETTINGS['a.a'] = 1
+        got = get_settings()
+        self.assertIn('a', got)
+        self.assertEqual(got['a'], 1)
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/tests/travis_env.sh b/tests/travis_env.sh
new file mode 100644
index 00000000..e2e59613
--- /dev/null
+++ b/tests/travis_env.sh
@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+
+[[ -z ${VNPY_TEST_MYSQL_DATABASE} ]] && VNPY_TEST_MYSQL_DATABASE=vnpy
+[[ -z ${VNPY_TEST_MYSQL_HOST} ]] && VNPY_TEST_MYSQL_HOST=127.0.0.1
+[[ -z ${VNPY_TEST_MYSQL_PORT} ]] && VNPY_TEST_MYSQL_PORT=3306
+[[ -z ${VNPY_TEST_MYSQL_USER} ]] && VNPY_TEST_MYSQL_USER=root
+[[ -z ${VNPY_TEST_MYSQL_PASSWORD} ]] && VNPY_TEST_MYSQL_PASSWORD=
+[[ -z ${VNPY_TEST_POSTGRESQL_DATABASE} ]] && VNPY_TEST_POSTGRESQL_DATABASE=vnpy
+[[ -z ${VNPY_TEST_POSTGRESQL_HOST} ]] && VNPY_TEST_POSTGRESQL_HOST=127.0.0.1
+[[ -z ${VNPY_TEST_POSTGRESQL_PORT} ]] && VNPY_TEST_POSTGRESQL_PORT=5432
+[[ -z ${VNPY_TEST_POSTGRESQL_USER} ]] && VNPY_TEST_POSTGRESQL_USER=postgres
+[[ -z ${VNPY_TEST_POSTGRESQL_PASSWORD} ]] && VNPY_TEST_POSTGRESQL_PASSWORD=
+[[ -z ${VNPY_TEST_MONGODB_DATABASE} ]] && VNPY_TEST_MONGODB_DATABASE=vnpy
+[[ -z ${VNPY_TEST_MONGODB_HOST} ]] && VNPY_TEST_MONGODB_HOST=127.0.0.1
+[[ -z ${VNPY_TEST_MONGODB_PORT} ]] && VNPY_TEST_MONGODB_PORT=27017
+
+
+export VNPY_TEST_MYSQL_DATABASE
+export VNPY_TEST_MYSQL_HOST
+export VNPY_TEST_MYSQL_PORT
+export VNPY_TEST_MYSQL_USER
+export VNPY_TEST_MYSQL_PASSWORD
+export VNPY_TEST_POSTGRESQL_DATABASE
+export VNPY_TEST_POSTGRESQL_HOST
+export VNPY_TEST_POSTGRESQL_PORT
+export VNPY_TEST_POSTGRESQL_USER
+export VNPY_TEST_POSTGRESQL_PASSWORD
+export VNPY_TEST_MONGODB_DATABASE
+export VNPY_TEST_MONGODB_HOST
+export VNPY_TEST_MONGODB_PORT
diff --git a/vnpy/app/csv_loader/engine.py b/vnpy/app/csv_loader/engine.py
index fa88afe7..a9ff1936 100644
--- a/vnpy/app/csv_loader/engine.py
+++ b/vnpy/app/csv_loader/engine.py
@@ -22,14 +22,13 @@ Sample csv file:
 
 import csv
 from datetime import datetime
-
-from peewee import chunked
+from typing import TextIO
 
 from vnpy.event import EventEngine
 from vnpy.trader.constant import Exchange, Interval
-from vnpy.trader.database import DbBarData, DB
+from vnpy.trader.database import database_manager
 from vnpy.trader.engine import BaseEngine, MainEngine
-
+from vnpy.trader.object import BarData
 
 APP_NAME = "CsvLoader"
 
@@ -53,6 +52,59 @@ class CsvLoaderEngine(BaseEngine):
         self.high_head: str = ""
         self.volume_head: str = ""
 
+    def load_by_handle(
+        self,
+        f: TextIO,
+        symbol: str,
+        exchange: Exchange,
+        interval: Interval,
+        datetime_head: str,
+        open_head: str,
+        close_head: str,
+        low_head: str,
+        high_head: str,
+        volume_head: str,
+        datetime_format: str,
+    ):
+        """
+        load by text mode file handle
+        """
+        reader = csv.DictReader(f)
+
+        bars = []
+        start = None
+        count = 0
+        for item in reader:
+            if datetime_format:
+                dt = datetime.strptime(item[datetime_head], datetime_format)
+            else:
+                dt = datetime.fromisoformat(item[datetime_head])
+
+            bar = BarData(
+                symbol=symbol,
+                exchange=exchange,
+                datetime=dt,
+                interval=interval,
+                volume=item[volume_head],
+                open_price=item[open_head],
+                high_price=item[high_head],
+                low_price=item[low_head],
+                close_price=item[close_head],
+                gateway_name="DB",
+            )
+
+            bars.append(bar)
+
+            # do some statistics
+            count += 1
+            if not start:
+                start = bar.datetime
+        end = bar.datetime
+
+        # insert into database
+        database_manager.save_bar_data(bars)
+        return start, end, count
+
     def load(
         self,
         file_path: str,
@@ -65,49 +117,22 @@ class CsvLoaderEngine(BaseEngine):
         low_head: str,
         high_head: str,
         volume_head: str,
-        datetime_format: str
+        datetime_format: str,
     ):
-        """"""
-        vt_symbol = f"{symbol}.{exchange.value}"
-
-        start = None
-        end = None
-        count = 0
-
+        """
+        load by filename
+        """
         with open(file_path, "rt") as f:
-            reader = csv.DictReader(f)
-
-            db_bars = []
-
-            for item in reader:
-                dt = datetime.strptime(item[datetime_head], datetime_format)
-
-                db_bar = {
-                    "symbol": symbol,
-                    "exchange": exchange.value,
-                    "datetime": dt,
-                    "interval": interval.value,
-                    "volume": item[volume_head],
-                    "open_price": item[open_head],
-                    "high_price": item[high_head],
-                    "low_price": item[low_head],
-                    "close_price": item[close_head],
-                    "vt_symbol": vt_symbol,
-                    "gateway_name": "DB"
-                }
-
-                db_bars.append(db_bar)
-
-                # do some statistics
-                count += 1
-                if not start:
-                    start = db_bar["datetime"]
-
-        end = db_bar["datetime"]
-
-        # Insert into DB
-        with DB.atomic():
-            for batch in chunked(db_bars, 50):
-                DbBarData.insert_many(batch).on_conflict_replace().execute()
-
-        return start, end, count
+            return self.load_by_handle(
+                f,
+                symbol=symbol,
+                exchange=exchange,
+                interval=interval,
+                datetime_head=datetime_head,
+                open_head=open_head,
+                close_head=close_head,
+                low_head=low_head,
+                high_head=high_head,
+                volume_head=volume_head,
+                datetime_format=datetime_format,
+            )
diff --git a/vnpy/app/cta_strategy/backtesting.py b/vnpy/app/cta_strategy/backtesting.py
index aeb5ddc1..01423bf5 100644
--- a/vnpy/app/cta_strategy/backtesting.py
+++ b/vnpy/app/cta_strategy/backtesting.py
@@ -12,8 +12,8 @@ from pandas import DataFrame
 
 from vnpy.trader.constant import (Direction, Offset, Exchange, 
                                   Interval, Status)
-from vnpy.trader.database import DbBarData, DbTickData
-from vnpy.trader.object import OrderData, TradeData
+from vnpy.trader.database import database_manager
+from vnpy.trader.object import OrderData, TradeData, BarData, TickData
 from vnpy.trader.utility import round_to_pricetick
 
 from .base import (
@@ -103,8 +103,8 @@ class BacktestingEngine:
 
         self.strategy_class = None
         self.strategy = None
-        self.tick = None
-        self.bar = None
+        self.tick: TickData
+        self.bar: BarData
         self.datetime = None
 
         self.interval = None
@@ -199,14 +199,16 @@ class BacktestingEngine:
 
         if self.mode == BacktestingMode.BAR:
             self.history_data = load_bar_data(
-                self.vt_symbol,
+                self.symbol,
+                self.exchange,
                 self.interval,
                 self.start,
                 self.end
             )
         else:
             self.history_data = load_tick_data(
-                self.vt_symbol,
+                self.symbol,
+                self.exchange,
                 self.start,
                 self.end
             )
@@ -520,7 +522,7 @@ class BacktestingEngine:
         else:
             self.daily_results[d] = DailyResult(d, price)
 
-    def new_bar(self, bar: DbBarData):
+    def new_bar(self, bar: BarData):
         """"""
         self.bar = bar
         self.datetime = bar.datetime
@@ -531,7 +533,7 @@ class BacktestingEngine:
 
         self.update_daily_close(bar.close_price)
 
-    def new_tick(self, tick: DbTickData):
+    def new_tick(self, tick: TickData):
         """"""
         self.tick = tick
         self.datetime = tick.datetime
@@ -966,41 +968,26 @@ def optimize(
 
 @lru_cache(maxsize=10)
 def load_bar_data(
-    vt_symbol: str, 
-    interval: str, 
-    start: datetime, 
+    symbol: str,
+    exchange: Exchange,
+    interval: Interval,
+    start: datetime,
     end: datetime
 ):
     """"""
-    s = (
-        DbBarData.select()
-        .where(
-            (DbBarData.vt_symbol == vt_symbol) 
-            & (DbBarData.interval == interval) 
-            & (DbBarData.datetime >= start) 
-            & (DbBarData.datetime <= end)
-        )
-        .order_by(DbBarData.datetime)
+    return database_manager.load_bar_data(
+        symbol, exchange, interval, start, end
     )
-    data = [db_bar.to_bar() for db_bar in s]
-    return data
 
 
 @lru_cache(maxsize=10)
 def load_tick_data(
-    vt_symbol: str, 
-    start: datetime, 
+    symbol: str,
+    exchange: Exchange,
+    start: datetime,
     end: datetime
 ):
     """"""
-    s = (
-        DbTickData.select()
-        .where(
-            (DbTickData.vt_symbol == vt_symbol) 
-            & (DbTickData.datetime >= start) 
-            & (DbTickData.datetime <= end)
-        )
-        .order_by(DbTickData.datetime)
+    return database_manager.load_tick_data(
+        symbol, exchange, start, end
     )
-    data = [db_tick.db_tick() for db_tick in s]
-    return data
\ No newline at end of file
diff --git a/vnpy/app/cta_strategy/engine.py b/vnpy/app/cta_strategy/engine.py
index 37e5973a..7824ff2d 100644
--- a/vnpy/app/cta_strategy/engine.py
+++ b/vnpy/app/cta_strategy/engine.py
@@ -5,7 +5,7 @@ import os
 import traceback
 from collections import defaultdict
 from pathlib import Path
-from typing import Any, Callable
+from typing import Any, Callable, List
 from datetime import datetime, timedelta
 from threading import Thread
 from queue import Queue
@@ -36,7 +36,7 @@ from vnpy.trader.constant import (
     Status
 )
 from vnpy.trader.utility import load_json, save_json
-from vnpy.trader.database import DbTickData, DbBarData
+from vnpy.trader.database import database_manager
 from vnpy.trader.setting import SETTINGS
 
 from .base import (
@@ -146,13 +146,12 @@ class CtaEngine(BaseEngine):
         self.write_log("RQData数据接口初始化成功")
 
     def query_bar_from_rq(
-        self, vt_symbol: str, interval: Interval, start: datetime, end: datetime
+        self, symbol: str, exchange: Exchange, interval: Interval, start: datetime, end: datetime
     ):
         """
         Query bar data from RQData.
         """
-        symbol, exchange_str = vt_symbol.split(".")
-        rq_symbol = to_rq_symbol(vt_symbol)
+        rq_symbol = to_rq_symbol(symbol, exchange)
         if rq_symbol not in self.rq_symbols:
             return None
         
@@ -166,11 +165,11 @@ class CtaEngine(BaseEngine):
             end_date=end
         )
 
-        data = []
+        data: List[BarData] = []
         for ix, row in df.iterrows():
             bar = BarData(
                 symbol=symbol,
-                exchange=Exchange(exchange_str),
+                exchange=exchange,
                 interval=interval,
                 datetime=row.name.to_pydatetime(),
                 open_price=row["open"],
@@ -529,46 +528,41 @@ class CtaEngine(BaseEngine):
         return self.engine_type
 
     def load_bar(
-        self, vt_symbol: str, days: int, interval: Interval, callback: Callable
+        self, symbol: str, exchange: Exchange, days: int, interval: Interval,
+        callback: Callable[[BarData], None]
     ):
         """"""
         end = datetime.now()
         start = end - timedelta(days)
 
-        # Query data from RQData by default, if not found, load from database.
-        data = self.query_bar_from_rq(vt_symbol, interval, start, end)
-        if not data:
-            s = (
-                DbBarData.select()
-                .where(
-                    (DbBarData.vt_symbol == vt_symbol)
-                    & (DbBarData.interval == interval.value)
-                    & (DbBarData.datetime >= start)
-                    & (DbBarData.datetime <= end)
-                )
-                .order_by(DbBarData.datetime)
+        # Query bars from RQData by default, if not found, load from database.
+        bars = self.query_bar_from_rq(symbol, exchange, interval, start, end)
+        if not bars:
+            bars = database_manager.load_bar_data(
+                symbol=symbol,
+                exchange=exchange,
+                interval=interval,
+                start=start,
+                end=end,
             )
-            data = [db_bar.to_bar() for db_bar in s]
 
-        for bar in data:
+        for bar in bars:
             callback(bar)
 
-    def load_tick(self, vt_symbol: str, days: int, callback: Callable):
+    def load_tick(self, symbol: str, exchange: Exchange, days: int,
+                  callback: Callable[[TickData], None]):
         """"""
         end = datetime.now()
         start = end - timedelta(days)
 
-        s = (
-            DbTickData.select()
-            .where(
-                (DbBarData.vt_symbol == vt_symbol)
-                & (DbBarData.datetime >= start)
-                & (DbBarData.datetime <= end)
-            )
-            .order_by(DbBarData.datetime)
+        ticks = database_manager.load_tick_data(
+            symbol=symbol,
+            exchange=exchange,
+            start=start,
+            end=end,
         )
 
-        for tick in s:
+        for tick in ticks:
             callback(tick)
 
     def call_strategy_func(
@@ -757,7 +751,7 @@ class CtaEngine(BaseEngine):
         """
         Load strategy class from certain folder.
         """
-        for dirpath, dirnames, filenames in os.walk(path):
+        for dirpath, dirnames, filenames in os.walk(str(path)):
             for filename in filenames:
                 if filename.endswith(".py"):
                     strategy_module_name = ".".join(
@@ -914,19 +908,19 @@ class CtaEngine(BaseEngine):
         self.main_engine.send_email(subject, msg)
 
 
-def to_rq_symbol(vt_symbol: str):
+def to_rq_symbol(symbol: str, exchange: Exchange):
     """
     CZCE product of RQData has symbol like "TA1905" while
     vt symbol is "TA905.CZCE" so need to add "1" in symbol.
     """
-    symbol, exchange_str = vt_symbol.split(".")
-    if exchange_str != "CZCE":
+    if exchange is not Exchange.CZCE:
         return symbol.upper()
 
     for count, word in enumerate(symbol):
         if word.isdigit():
             break
-    
+
+    # noinspection PyUnboundLocalVariable
     product = symbol[:count]
     year = symbol[count]
     month = symbol[count + 1:]
diff --git a/vnpy/trader/database.py b/vnpy/trader/database.py
deleted file mode 100644
index 1e90dcbc..00000000
--- a/vnpy/trader/database.py
+++ /dev/null
@@ -1,268 +0,0 @@
-""""""
-
-from peewee import CharField, DateTimeField, FloatField, Model, MySQLDatabase, PostgresqlDatabase, \
-    SqliteDatabase
-
-from .constant import Exchange, Interval
-from .object import BarData, TickData
-from .setting import SETTINGS
-from .utility import resolve_path
-
-
-def init():
-    db_settings = SETTINGS['database']
-    driver = db_settings["driver"]
-
-    init_funcs = {
-        "sqlite": init_sqlite,
-        "mysql": init_mysql,
-        "postgresql": init_postgresql,
-    }
-
-    assert driver in init_funcs
-    del db_settings['driver']
-    return init_funcs[driver](db_settings)
-
-
-def init_sqlite(settings: dict):
-    global DB
-    database = settings['database']
-
-    DB = SqliteDatabase(str(resolve_path(database)))
-
-
-def init_mysql(settings: dict):
-    global DB
-    DB = MySQLDatabase(**settings)
-
-
-def init_postgresql(settings: dict):
-    global DB
-    DB = PostgresqlDatabase(**settings)
-
-
-init()
-
-
-class DbBarData(Model):
-    """
-    Candlestick bar data for database storage.
-
-    Index is defined unique with vt_symbol, interval and datetime.
-    """
-
-    symbol = CharField()
-    exchange = CharField()
-    datetime = DateTimeField()
-    interval = CharField()
-
-    volume = FloatField()
-    open_price = FloatField()
-    high_price = FloatField()
-    low_price = FloatField()
-    close_price = FloatField()
-
-    vt_symbol = CharField()
-    gateway_name = CharField()
-
-    class Meta:
-        database = DB
-        indexes = ((("vt_symbol", "interval", "datetime"), True),)
-
-    @staticmethod
-    def from_bar(bar: BarData):
-        """
-        Generate DbBarData object from BarData.
-        """
-        db_bar = DbBarData()
-
-        db_bar.symbol = bar.symbol
-        db_bar.exchange = bar.exchange.value
-        db_bar.datetime = bar.datetime
-        db_bar.interval = bar.interval.value
-        db_bar.volume = bar.volume
-        db_bar.open_price = bar.open_price
-        db_bar.high_price = bar.high_price
-        db_bar.low_price = bar.low_price
-        db_bar.close_price = bar.close_price
-        db_bar.vt_symbol = bar.vt_symbol
-        db_bar.gateway_name = "DB"
-
-        return db_bar
-
-    def to_bar(self):
-        """
-        Generate BarData object from DbBarData.
-        """
-        bar = BarData(
-            symbol=self.symbol,
-            exchange=Exchange(self.exchange),
-            datetime=self.datetime,
-            interval=Interval(self.interval),
-            volume=self.volume,
-            open_price=self.open_price,
-            high_price=self.high_price,
-            low_price=self.low_price,
-            close_price=self.close_price,
-            gateway_name=self.gateway_name,
-        )
-        return bar
-
-
-class DbTickData(Model):
-    """
-    Tick data for database storage.
-
-    Index is defined unique with vt_symbol, interval and datetime.
-    """
-
-    symbol = CharField()
-    exchange = CharField()
-    datetime = DateTimeField()
-
-    name = CharField()
-    volume = FloatField()
-    last_price = FloatField()
-    last_volume = FloatField()
-    limit_up = FloatField()
-    limit_down = FloatField()
-
-    open_price = FloatField()
-    high_price = FloatField()
-    low_price = FloatField()
-    close_price = FloatField()
-
-    bid_price_1 = FloatField()
-    bid_price_2 = FloatField()
-    bid_price_3 = FloatField()
-    bid_price_4 = FloatField()
-    bid_price_5 = FloatField()
-
-    ask_price_1 = FloatField()
-    ask_price_2 = FloatField()
-    ask_price_3 = FloatField()
-    ask_price_4 = FloatField()
-    ask_price_5 = FloatField()
-
-    bid_volume_1 = FloatField()
-    bid_volume_2 = FloatField()
-    bid_volume_3 = FloatField()
-    bid_volume_4 = FloatField()
-    bid_volume_5 = FloatField()
-
-    ask_volume_1 = FloatField()
-    ask_volume_2 = FloatField()
-    ask_volume_3 = FloatField()
-    ask_volume_4 = FloatField()
-    ask_volume_5 = FloatField()
-
-    vt_symbol = CharField()
-    gateway_name = CharField()
-
-    class Meta:
-        database = DB
-        indexes = ((("vt_symbol", "datetime"), True),)
-
-    @staticmethod
-    def from_tick(tick: TickData):
-        """
-        Generate DbTickData object from TickData.
-        """
-        db_tick = DbTickData()
-
-        db_tick.symbol = tick.symbol
-        db_tick.exchange = tick.exchange.value
-        db_tick.datetime = tick.datetime
-        db_tick.name = tick.name
-        db_tick.volume = tick.volume
-        db_tick.last_price = tick.last_price
-        db_tick.last_volume = tick.last_volume
-        db_tick.limit_up = tick.limit_up
-        db_tick.limit_down = tick.limit_down
-        db_tick.open_price = tick.open_price
-        db_tick.high_price = tick.high_price
-        db_tick.low_price = tick.low_price
-        db_tick.pre_close = tick.pre_close
-
-        db_tick.bid_price_1 = tick.bid_price_1
-        db_tick.ask_price_1 = tick.ask_price_1
-        db_tick.bid_volume_1 = tick.bid_volume_1
-        db_tick.ask_volume_1 = tick.ask_volume_1
-
-        if tick.bid_price_2:
-            db_tick.bid_price_2 = tick.bid_price_2
-            db_tick.bid_price_3 = tick.bid_price_3
-            db_tick.bid_price_4 = tick.bid_price_4
-            db_tick.bid_price_5 = tick.bid_price_5
-
-            db_tick.ask_price_2 = tick.ask_price_2
-            db_tick.ask_price_3 = tick.ask_price_3
-            db_tick.ask_price_4 = tick.ask_price_4
-            db_tick.ask_price_5 = tick.ask_price_5
-
-            db_tick.bid_volume_2 = tick.bid_volume_2
-            db_tick.bid_volume_3 = tick.bid_volume_3
-            db_tick.bid_volume_4 = tick.bid_volume_4
-            db_tick.bid_volume_5 = tick.bid_volume_5
-
-            db_tick.ask_volume_2 = tick.ask_volume_2
-            db_tick.ask_volume_3 = tick.ask_volume_3
-            db_tick.ask_volume_4 = tick.ask_volume_4
-            db_tick.ask_volume_5 = tick.ask_volume_5
-
-        db_tick.vt_symbol = tick.vt_symbol
-        db_tick.gateway_name = "DB"
-
-        return tick
-
-    def to_tick(self):
-        """
-        Generate TickData object from DbTickData.
-        """
-        tick = TickData(
-            symbol=self.symbol,
-            exchange=Exchange(self.exchange),
-            datetime=self.datetime,
-            name=self.name,
-            volume=self.volume,
-            last_price=self.last_price,
-            last_volume=self.last_volume,
-            limit_up=self.limit_up,
-            limit_down=self.limit_down,
-            open_price=self.open_price,
-            high_price=self.high_price,
-            low_price=self.low_price,
-            pre_close=self.pre_close,
-            bid_price_1=self.bid_price_1,
-            ask_price_1=self.ask_price_1,
-            bid_volume_1=self.bid_volume_1,
-            ask_volume_1=self.ask_volume_1,
-            gateway_name=self.gateway_name,
-        )
-
-        if self.bid_price_2:
-            tick.bid_price_2 = self.bid_price_2
-            tick.bid_price_3 = self.bid_price_3
-            tick.bid_price_4 = self.bid_price_4
-            tick.bid_price_5 = self.bid_price_5
-
-            tick.ask_price_2 = self.ask_price_2
-            tick.ask_price_3 = self.ask_price_3
-            tick.ask_price_4 = self.ask_price_4
-            tick.ask_price_5 = self.ask_price_5
-
-            tick.bid_volume_2 = self.bid_volume_2
-            tick.bid_volume_3 = self.bid_volume_3
-            tick.bid_volume_4 = self.bid_volume_4
-            tick.bid_volume_5 = self.bid_volume_5
-
-            tick.ask_volume_2 = self.ask_volume_2
-            tick.ask_volume_3 = self.ask_volume_3
-            tick.ask_volume_4 = self.ask_volume_4
-            tick.ask_volume_5 = self.ask_volume_5
-
-        return tick
-
-
-DB.connect()
-DB.create_tables([DbBarData, DbTickData])
diff --git a/vnpy/trader/database/__init__.py b/vnpy/trader/database/__init__.py
new file mode 100644
index 00000000..16cb96b8
--- /dev/null
+++ b/vnpy/trader/database/__init__.py
@@ -0,0 +1,12 @@
+import os
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from vnpy.trader.database.database import BaseDatabaseManager
+
+if "VNPY_TESTING" not in os.environ:
+    from vnpy.trader.setting import get_settings
+    from .initialize import init
+
+    settings = get_settings("database.")
+    database_manager: "BaseDatabaseManager" = init(settings=settings)
diff --git a/vnpy/trader/database/database.py b/vnpy/trader/database/database.py
new file mode 100644
index 00000000..ec765e8d
--- /dev/null
+++ b/vnpy/trader/database/database.py
@@ -0,0 +1,53 @@
+from abc import ABC, abstractmethod
+from datetime import datetime
+from enum import Enum
+from typing import Sequence, TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from vnpy.trader.constant import Interval, Exchange  # noqa
+    from vnpy.trader.object import BarData, TickData  # noqa
+
+
+class Driver(Enum):
+    SQLITE = "sqlite"
+    MYSQL = "mysql"
+    POSTGRESQL = "postgresql"
+    MONGODB = "mongodb"
+
+
+class BaseDatabaseManager(ABC):
+
+    @abstractmethod
+    def load_bar_data(
+        self,
+        symbol: str,
+        exchange: "Exchange",
+        interval: "Interval",
+        start: datetime,
+        end: datetime
+    ) -> Sequence["BarData"]:
+        pass
+
+    @abstractmethod
+    def load_tick_data(
+        self,
+        symbol: str,
+        exchange: "Exchange",
+        start: datetime,
+        end: datetime
+    ) -> Sequence["TickData"]:
+        pass
+
+    @abstractmethod
+    def save_bar_data(
+        self,
+        datas: Sequence["BarData"],
+    ):
+        pass
+
+    @abstractmethod
+    def save_tick_data(
+        self,
+        datas: Sequence["TickData"],
+    ):
+        pass
diff --git a/vnpy/trader/database/database_mongo.py b/vnpy/trader/database/database_mongo.py
new file mode 100644
index 00000000..ef5038e1
--- /dev/null
+++ b/vnpy/trader/database/database_mongo.py
@@ -0,0 +1,302 @@
+from datetime import datetime
+from enum import Enum
+from typing import Sequence
+
+from mongoengine import DateTimeField, Document, FloatField, StringField, connect
+
+from vnpy.trader.constant import Exchange, Interval
+from vnpy.trader.object import BarData, TickData
+from .database import BaseDatabaseManager, Driver
+
+
+def init(_: Driver, settings: dict):
+    database = settings["database"]
+    host = settings["host"]
+    port = settings["port"]
+    username = settings["user"]
+    password = settings["password"]
+    authentication_source = settings["authentication_source"]
+    if not username:  # if username == '' or None, skip username
+        username = None
+        password = None
+        authentication_source = None
+    connect(
+        db=database,
+        host=host,
+        port=port,
+        username=username,
+        password=password,
+        authentication_source=authentication_source,
+    )
+    return MongoManager()
+
+
+class DbBarData(Document):
+    """
+    Candlestick bar data for database storage.
+
+    Index is defined unique with datetime, interval, symbol
+    """
+
+    symbol: str = StringField()
+    exchange: str = StringField()
+    datetime: datetime = DateTimeField()
+    interval: str = StringField()
+
+    volume: float = FloatField()
+    open_price: float = FloatField()
+    high_price: float = FloatField()
+    low_price: float = FloatField()
+    close_price: float = FloatField()
+
+    meta = {
+        "indexes": [
+            {"fields": ("datetime", "interval", "symbol", "exchange"), "unique": True}
+        ]
+    }
+
+    @staticmethod
+    def from_bar(bar: BarData):
+        """
+        Generate DbBarData object from BarData.
+        """
+        db_bar = DbBarData()
+
+        db_bar.symbol = bar.symbol
+        db_bar.exchange = bar.exchange.value
+        db_bar.datetime = bar.datetime
+        db_bar.interval = bar.interval.value
+        db_bar.volume = bar.volume
+        db_bar.open_price = bar.open_price
+        db_bar.high_price = bar.high_price
+        db_bar.low_price = bar.low_price
+        db_bar.close_price = bar.close_price
+
+        return db_bar
+
+    def to_bar(self):
+        """
+        Generate BarData object from DbBarData.
+        """
+        bar = BarData(
+            symbol=self.symbol,
+            exchange=Exchange(self.exchange),
+            datetime=self.datetime,
+            interval=Interval(self.interval),
+            volume=self.volume,
+            open_price=self.open_price,
+            high_price=self.high_price,
+            low_price=self.low_price,
+            close_price=self.close_price,
+            gateway_name="DB",
+        )
+        return bar
+
+
+class DbTickData(Document):
+    """
+    Tick data for database storage.
+
+    Index is defined unique with (datetime, symbol)
+    """
+
+    symbol: str = StringField()
+    exchange: str = StringField()
+    datetime: datetime = DateTimeField()
+
+    name: str = StringField()
+    volume: float = FloatField()
+    last_price: float = FloatField()
+    last_volume: float = FloatField()
+    limit_up: float = FloatField()
+    limit_down: float = FloatField()
+
+    open_price: float = FloatField()
+    high_price: float = FloatField()
+    low_price: float = FloatField()
+    close_price: float = FloatField()
+    pre_close: float = FloatField()
+
+    bid_price_1: float = FloatField()
+    bid_price_2: float = FloatField()
+    bid_price_3: float = FloatField()
+    bid_price_4: float = FloatField()
+    bid_price_5: float = FloatField()
+
+    ask_price_1: float = FloatField()
+    ask_price_2: float = FloatField()
+    ask_price_3: float = FloatField()
+    ask_price_4: float = FloatField()
+    ask_price_5: float = FloatField()
+
+    bid_volume_1: float = FloatField()
+    bid_volume_2: float = FloatField()
+    bid_volume_3: float = FloatField()
+    bid_volume_4: float = FloatField()
+    bid_volume_5: float = FloatField()
+
+    ask_volume_1: float = FloatField()
+    ask_volume_2: float = FloatField()
+    ask_volume_3: float = FloatField()
+    ask_volume_4: float = FloatField()
+    ask_volume_5: float = FloatField()
+
+    meta = {"indexes": [{"fields": ("datetime", "symbol", "exchange"), "unique": True}]}
+
+    @staticmethod
+    def from_tick(tick: TickData):
+        """
+        Generate DbTickData object from TickData.
+        """
+        db_tick = DbTickData()
+
+        db_tick.symbol = tick.symbol
+        db_tick.exchange = tick.exchange.value
+        db_tick.datetime = tick.datetime
+        db_tick.name = tick.name
+        db_tick.volume = tick.volume
+        db_tick.last_price = tick.last_price
+        db_tick.last_volume = tick.last_volume
+        db_tick.limit_up = tick.limit_up
+        db_tick.limit_down = tick.limit_down
+        db_tick.open_price = tick.open_price
+        db_tick.high_price = tick.high_price
+        db_tick.low_price = tick.low_price
+        db_tick.pre_close = tick.pre_close
+
+        db_tick.bid_price_1 = tick.bid_price_1
+        db_tick.ask_price_1 = tick.ask_price_1
+        db_tick.bid_volume_1 = tick.bid_volume_1
+        db_tick.ask_volume_1 = tick.ask_volume_1
+
+        if tick.bid_price_2:
+            db_tick.bid_price_2 = tick.bid_price_2
+            db_tick.bid_price_3 = tick.bid_price_3
+            db_tick.bid_price_4 = tick.bid_price_4
+            db_tick.bid_price_5 = tick.bid_price_5
+
+            db_tick.ask_price_2 = tick.ask_price_2
+            db_tick.ask_price_3 = tick.ask_price_3
+            db_tick.ask_price_4 = tick.ask_price_4
+            db_tick.ask_price_5 = tick.ask_price_5
+
+            db_tick.bid_volume_2 = tick.bid_volume_2
+            db_tick.bid_volume_3 = tick.bid_volume_3
+            db_tick.bid_volume_4 = tick.bid_volume_4
+            db_tick.bid_volume_5 = tick.bid_volume_5
+
+            db_tick.ask_volume_2 = tick.ask_volume_2
+            db_tick.ask_volume_3 = tick.ask_volume_3
+            db_tick.ask_volume_4 = tick.ask_volume_4
+            db_tick.ask_volume_5 = tick.ask_volume_5
+
+        return db_tick
+
+    def to_tick(self):
+        """
+        Generate TickData object from DbTickData.
+        """
+        tick = TickData(
+            symbol=self.symbol,
+            exchange=Exchange(self.exchange),
+            datetime=self.datetime,
+            name=self.name,
+            volume=self.volume,
+            last_price=self.last_price,
+            last_volume=self.last_volume,
+            limit_up=self.limit_up,
+            limit_down=self.limit_down,
+            open_price=self.open_price,
+            high_price=self.high_price,
+            low_price=self.low_price,
+            pre_close=self.pre_close,
+            bid_price_1=self.bid_price_1,
+            ask_price_1=self.ask_price_1,
+            bid_volume_1=self.bid_volume_1,
+            ask_volume_1=self.ask_volume_1,
+            gateway_name="DB",
+        )
+
+        if self.bid_price_2:
+            tick.bid_price_2 = self.bid_price_2
+            tick.bid_price_3 = self.bid_price_3
+            tick.bid_price_4 = self.bid_price_4
+            tick.bid_price_5 = self.bid_price_5
+
+            tick.ask_price_2 = self.ask_price_2
+            tick.ask_price_3 = self.ask_price_3
+            tick.ask_price_4 = self.ask_price_4
+            tick.ask_price_5 = self.ask_price_5
+
+            tick.bid_volume_2 = self.bid_volume_2
+            tick.bid_volume_3 = self.bid_volume_3
+            tick.bid_volume_4 = self.bid_volume_4
+            tick.bid_volume_5 = self.bid_volume_5
+
+            tick.ask_volume_2 = self.ask_volume_2
+            tick.ask_volume_3 = self.ask_volume_3
+            tick.ask_volume_4 = self.ask_volume_4
+            tick.ask_volume_5 = self.ask_volume_5
+
+        return tick
+
+
+class MongoManager(BaseDatabaseManager):
+    def load_bar_data(
+        self,
+        symbol: str,
+        exchange: Exchange,
+        interval: Interval,
+        start: datetime,
+        end: datetime,
+    ) -> Sequence[BarData]:
+        s = DbBarData.objects(
+            symbol=symbol,
+            exchange=exchange.value,
+            interval=interval.value,
+            datetime__gte=start,
+            datetime__lte=end,
+        )
+        data = [db_bar.to_bar() for db_bar in s]
+        return data
+
+    def load_tick_data(
+        self, symbol: str, exchange: Exchange, start: datetime, end: datetime
+    ) -> Sequence[TickData]:
+        s = DbTickData.objects(
+            symbol=symbol,
+            exchange=exchange.value,
+            datetime__gte=start,
+            datetime__lte=end,
+        )
+        data = [db_tick.to_tick() for db_tick in s]
+        return data
+
+    @staticmethod
+    def to_update_param(d):
+        return {
+            "set__" + k: v.value if isinstance(v, Enum) else v
+            for k, v in d.__dict__.items()
+        }
+
+    def save_bar_data(self, datas: Sequence[BarData]):
+        for d in datas:
+            updates = self.to_update_param(d)
+            updates.pop("set__gateway_name")
+            updates.pop("set__vt_symbol")
+            (
+                DbBarData.objects(
+                    symbol=d.symbol, interval=d.interval.value, datetime=d.datetime
+                ).update_one(upsert=True, **updates)
+            )
+
+    def save_tick_data(self, datas: Sequence[TickData]):
+        for d in datas:
+            updates = self.to_update_param(d)
+            updates.pop("set__gateway_name")
+            updates.pop("set__vt_symbol")
+            (
+                DbTickData.objects(
+                    symbol=d.symbol, exchange=d.exchange.value, datetime=d.datetime
+                ).update_one(upsert=True, **updates)
+            )
diff --git a/vnpy/trader/database/database_sql.py b/vnpy/trader/database/database_sql.py
new file mode 100644
index 00000000..61d6e2ff
--- /dev/null
+++ b/vnpy/trader/database/database_sql.py
@@ -0,0 +1,369 @@
+""""""
+from datetime import datetime
+from typing import List, Sequence, Type
+
+from peewee import (
+    AutoField,
+    CharField,
+    Database,
+    DateTimeField,
+    FloatField,
+    Model,
+    MySQLDatabase,
+    PostgresqlDatabase,
+    SqliteDatabase,
+    chunked,
+)
+
+from vnpy.trader.constant import Exchange, Interval
+from vnpy.trader.object import BarData, TickData
+from vnpy.trader.utility import get_file_path
+from .database import BaseDatabaseManager, Driver
+
+
+def init(driver: Driver, settings: dict):
+    init_funcs = {
+        Driver.SQLITE: init_sqlite,
+        Driver.MYSQL: init_mysql,
+        Driver.POSTGRESQL: init_postgresql,
+    }
+    assert driver in init_funcs
+
+    db = init_funcs[driver](settings)
+    bar, tick = init_models(db, driver)
+    return SqlManager(bar, tick)
+
+
+def init_sqlite(settings: dict):
+    database = settings["database"]
+    path = str(get_file_path(database))
+    db = SqliteDatabase(path)
+    return db
+
+
+def init_mysql(settings: dict):
+    keys = {"database", "user", "password", "host", "port"}
+    settings = {k: v for k, v in settings.items() if k in keys}
+    db = MySQLDatabase(**settings)
+    return db
+
+
+def init_postgresql(settings: dict):
+    keys = {"database", "user", "password", "host", "port"}
+    settings = {k: v for k, v in settings.items() if k in keys}
+    db = PostgresqlDatabase(**settings)
+    return db
+
+
+class ModelBase(Model):
+    def to_dict(self):
+        return self.__data__
+
+
+def init_models(db: Database, driver: Driver):
+    class DbBarData(ModelBase):
+        """
+        Candlestick bar data for database storage.
+
+        Index is defined unique with datetime, interval, symbol
+        """
+
+        id = AutoField()
+        symbol: str = CharField()
+        exchange: str = CharField()
+        datetime: datetime = DateTimeField()
+        interval: str = CharField()
+
+        volume: float = FloatField()
+        open_price: float = FloatField()
+        high_price: float = FloatField()
+        low_price: float = FloatField()
+        close_price: float = FloatField()
+
+        class Meta:
+            database = db
+            indexes = ((("datetime", "interval", "symbol", "exchange"), True),)
+
+        @staticmethod
+        def from_bar(bar: BarData):
+            """
+            Generate DbBarData object from BarData.
+            """
+            db_bar = DbBarData()
+
+            db_bar.symbol = bar.symbol
+            db_bar.exchange = bar.exchange.value
+            db_bar.datetime = bar.datetime
+            db_bar.interval = bar.interval.value
+            db_bar.volume = bar.volume
+            db_bar.open_price = bar.open_price
+            db_bar.high_price = bar.high_price
+            db_bar.low_price = bar.low_price
+            db_bar.close_price = bar.close_price
+
+            return db_bar
+
+        def to_bar(self):
+            """
+            Generate BarData object from DbBarData.
+            """
+            bar = BarData(
+                symbol=self.symbol,
+                exchange=Exchange(self.exchange),
+                datetime=self.datetime,
+                interval=Interval(self.interval),
+                volume=self.volume,
+                open_price=self.open_price,
+                high_price=self.high_price,
+                low_price=self.low_price,
+                close_price=self.close_price,
+                gateway_name="DB",
+            )
+            return bar
+
+        @staticmethod
+        def save_all(objs: List["DbBarData"]):
+            """
+            save a list of objects, update if exists.
+            """
+            dicts = [i.to_dict() for i in objs]
+            with db.atomic():
+                if driver is Driver.POSTGRESQL:
+                    for bar in dicts:
+                        DbBarData.insert(bar).on_conflict(
+                            update=bar,
+                            conflict_target=(
+                                DbBarData.datetime,
+                                DbBarData.interval,
+                                DbBarData.symbol,
+                                DbBarData.exchange,
+                            ),
+                        ).execute()
+                else:
+                    for c in chunked(dicts, 50):
+                        DbBarData.insert_many(c).on_conflict_replace().execute()
+
+    class DbTickData(ModelBase):
+        """
+        Tick data for database storage.
+
+        Index is defined unique with (datetime, symbol)
+        """
+
+        id = AutoField()
+
+        symbol: str = CharField()
+        exchange: str = CharField()
+        datetime: datetime = DateTimeField()
+
+        name: str = CharField()
+        volume: float = FloatField()
+        last_price: float = FloatField()
+        last_volume: float = FloatField()
+        limit_up: float = FloatField()
+        limit_down: float = FloatField()
+
+        open_price: float = FloatField()
+        high_price: float = FloatField()
+        low_price: float = FloatField()
+        pre_close: float = FloatField()
+
+        bid_price_1: float = FloatField()
+        bid_price_2: float = FloatField(null=True)
+        bid_price_3: float = FloatField(null=True)
+        bid_price_4: float = FloatField(null=True)
+        bid_price_5: float = FloatField(null=True)
+
+        ask_price_1: float = FloatField()
+        ask_price_2: float = FloatField(null=True)
+        ask_price_3: float = FloatField(null=True)
+        ask_price_4: float = FloatField(null=True)
+        ask_price_5: float = FloatField(null=True)
+
+        bid_volume_1: float = FloatField()
+        bid_volume_2: float = FloatField(null=True)
+        bid_volume_3: float = FloatField(null=True)
+        bid_volume_4: float = FloatField(null=True)
+        bid_volume_5: float = FloatField(null=True)
+
+        ask_volume_1: float = FloatField()
+        ask_volume_2: float = FloatField(null=True)
+        ask_volume_3: float = FloatField(null=True)
+        ask_volume_4: float = FloatField(null=True)
+        ask_volume_5: float = FloatField(null=True)
+
+        class Meta:
+            database = db
+            indexes = ((("datetime", "symbol", "exchange"), True),)
+
+        @staticmethod
+        def from_tick(tick: TickData):
+            """
+            Generate DbTickData object from TickData.
+            """
+            db_tick = DbTickData()
+
+            db_tick.symbol = tick.symbol
+            db_tick.exchange = tick.exchange.value
+            db_tick.datetime = tick.datetime
+            db_tick.name = tick.name
+            db_tick.volume = tick.volume
+            db_tick.last_price = tick.last_price
+            db_tick.last_volume = tick.last_volume
+            db_tick.limit_up = tick.limit_up
+            db_tick.limit_down = tick.limit_down
+            db_tick.open_price = tick.open_price
+            db_tick.high_price = tick.high_price
+            db_tick.low_price = tick.low_price
+            db_tick.pre_close = tick.pre_close
+
+            db_tick.bid_price_1 = tick.bid_price_1
+            db_tick.ask_price_1 = tick.ask_price_1
+            db_tick.bid_volume_1 = tick.bid_volume_1
+            db_tick.ask_volume_1 = tick.ask_volume_1
+
+            if tick.bid_price_2:
+                db_tick.bid_price_2 = tick.bid_price_2
+                db_tick.bid_price_3 = tick.bid_price_3
+                db_tick.bid_price_4 = tick.bid_price_4
+                db_tick.bid_price_5 = tick.bid_price_5
+
+                db_tick.ask_price_2 = tick.ask_price_2
+                db_tick.ask_price_3 = tick.ask_price_3
+                db_tick.ask_price_4 = tick.ask_price_4
+                db_tick.ask_price_5 = tick.ask_price_5
+
+                db_tick.bid_volume_2 = tick.bid_volume_2
+                db_tick.bid_volume_3 = tick.bid_volume_3
+                db_tick.bid_volume_4 = tick.bid_volume_4
+                db_tick.bid_volume_5 = tick.bid_volume_5
+
+                db_tick.ask_volume_2 = tick.ask_volume_2
+                db_tick.ask_volume_3 = tick.ask_volume_3
+                db_tick.ask_volume_4 = tick.ask_volume_4
+                db_tick.ask_volume_5 = tick.ask_volume_5
+
+            return db_tick
+
+        def to_tick(self):
+            """
+            Generate TickData object from DbTickData.
+            """
+            tick = TickData(
+                symbol=self.symbol,
+                exchange=Exchange(self.exchange),
+                datetime=self.datetime,
+                name=self.name,
+                volume=self.volume,
+                last_price=self.last_price,
+                last_volume=self.last_volume,
+                limit_up=self.limit_up,
+                limit_down=self.limit_down,
+                open_price=self.open_price,
+                high_price=self.high_price,
+                low_price=self.low_price,
+                pre_close=self.pre_close,
+                bid_price_1=self.bid_price_1,
+                ask_price_1=self.ask_price_1,
+                bid_volume_1=self.bid_volume_1,
+                ask_volume_1=self.ask_volume_1,
+                gateway_name="DB",
+            )
+
+            if self.bid_price_2:
+                tick.bid_price_2 = self.bid_price_2
+                tick.bid_price_3 = self.bid_price_3
+                tick.bid_price_4 = self.bid_price_4
+                tick.bid_price_5 = self.bid_price_5
+
+                tick.ask_price_2 = self.ask_price_2
+                tick.ask_price_3 = self.ask_price_3
+                tick.ask_price_4 = self.ask_price_4
+                tick.ask_price_5 = self.ask_price_5
+
+                tick.bid_volume_2 = self.bid_volume_2
+                tick.bid_volume_3 = self.bid_volume_3
+                tick.bid_volume_4 = self.bid_volume_4
+                tick.bid_volume_5 = self.bid_volume_5
+
+                tick.ask_volume_2 = self.ask_volume_2
+                tick.ask_volume_3 = self.ask_volume_3
+                tick.ask_volume_4 = self.ask_volume_4
+                tick.ask_volume_5 = self.ask_volume_5
+
+            return tick
+
+        @staticmethod
+        def save_all(objs: List["DbTickData"]):
+            dicts = [i.to_dict() for i in objs]
+            with db.atomic():
+                if driver is Driver.POSTGRESQL:
+                    for tick in dicts:
+                        DbTickData.insert(tick).on_conflict(
+                            update=tick,
+                            conflict_target=(
+                                DbTickData.datetime,
+                                DbTickData.symbol,
+                                DbTickData.exchange,
+                            ),
+                        ).execute()
+                else:
+                    for c in chunked(dicts, 50):
+                        DbTickData.insert_many(c).on_conflict_replace().execute()
+
+    db.connect()
+    db.create_tables([DbBarData, DbTickData])
+    return DbBarData, DbTickData
+
+
+class SqlManager(BaseDatabaseManager):
+    def __init__(self, class_bar: Type[Model], class_tick: Type[Model]):
+        self.class_bar = class_bar
+        self.class_tick = class_tick
+
+    def load_bar_data(
+        self,
+        symbol: str,
+        exchange: Exchange,
+        interval: Interval,
+        start: datetime,
+        end: datetime,
+    ) -> Sequence[BarData]:
+        s = (
+            self.class_bar.select()
+            .where(
+                (self.class_bar.symbol == symbol)
+                & (self.class_bar.exchange == exchange.value)
+                & (self.class_bar.interval == interval.value)
+                & (self.class_bar.datetime >= start)
+                & (self.class_bar.datetime <= end)
+            )
+            .order_by(self.class_bar.datetime)
+        )
+        data = [db_bar.to_bar() for db_bar in s]
+        return data
+
+    def load_tick_data(
+        self, symbol: str, exchange: Exchange, start: datetime, end: datetime
+    ) -> Sequence[TickData]:
+        s = (
+            self.class_tick.select()
+            .where(
+                (self.class_tick.symbol == symbol)
+                & (self.class_tick.exchange == exchange.value)
+                & (self.class_tick.datetime >= start)
+                & (self.class_tick.datetime <= end)
+            )
+            .order_by(self.class_tick.datetime)
+        )
+
+        data = [db_tick.to_tick() for db_tick in s]
+        return data
+
+    def save_bar_data(self, datas: Sequence[BarData]):
+        ds = [self.class_bar.from_bar(i) for i in datas]
+        self.class_bar.save_all(ds)
+
+    def save_tick_data(self, datas: Sequence[TickData]):
+        ds = [self.class_tick.from_tick(i) for i in datas]
+        self.class_tick.save_all(ds)
diff --git a/vnpy/trader/database/initialize.py b/vnpy/trader/database/initialize.py
new file mode 100644
index 00000000..a15b484c
--- /dev/null
+++ b/vnpy/trader/database/initialize.py
@@ -0,0 +1,24 @@
+""""""
+from .database import BaseDatabaseManager, Driver
+
+
+def init(settings: dict) -> BaseDatabaseManager:
+    driver = Driver(settings["driver"])
+    if driver is Driver.MONGODB:
+        return init_nosql(driver=driver, settings=settings)
+    else:
+        return init_sql(driver=driver, settings=settings)
+
+
+def init_sql(driver: Driver, settings: dict):
+    from .database_sql import init
+    keys = {'database', "host", "port", "user", "password"}
+    settings = {k: v for k, v in settings.items() if k in keys}
+    _database_manager = init(driver, settings)
+    return _database_manager
+
+
+def init_nosql(driver: Driver, settings: dict):
+    from .database_mongo import init
+    _database_manager = init(driver, settings=settings)
+    return _database_manager
diff --git a/vnpy/trader/setting.py b/vnpy/trader/setting.py
index b27dbf96..1dd8b0ff 100644
--- a/vnpy/trader/setting.py
+++ b/vnpy/trader/setting.py
@@ -24,16 +24,21 @@ SETTINGS = {
 
     "rqdata.username": "",
     "rqdata.password": "",
-    "database": {
-        "driver": "sqlite",  # sqlite, mysql, postgresql
-        "database": "{VNPY_TEMP}/database.db",  # for sqlite, use this as filepath
-        "host": "localhost",
-        "port": 3306,
-        "user": "root",
-        "password": ""
-    }
+
+    "database.driver": "sqlite",  # see database.Driver
+    "database.database": "database.db",  # for sqlite, use this as filepath
+    "database.host": "localhost",
+    "database.port": 3306,
+    "database.user": "root",
+    "database.password": "",
+    "database.authentication_source": "admin",  # for mongodb
 }
 
 # Load global setting from json file.
 SETTING_FILENAME = "vt_setting.json"
 SETTINGS.update(load_json(SETTING_FILENAME))
+
+
+def get_settings(prefix: str = ""):
+    prefix_length = len(prefix)
+    return {k[prefix_length:]: v for k, v in SETTINGS.items() if k.startswith(prefix)}
diff --git a/vnpy/trader/utility.py b/vnpy/trader/utility.py
index 216dcbae..69fa6991 100644
--- a/vnpy/trader/utility.py
+++ b/vnpy/trader/utility.py
@@ -3,20 +3,28 @@ General utility functions.
 """
 
 import json
-import os
 from pathlib import Path
-from typing import Callable
+from typing import Callable, TYPE_CHECKING
 
 import numpy as np
 import talib
 
 from .object import BarData, TickData
 
+if TYPE_CHECKING:
+    from vnpy.trader.constant import Exchange
 
-def resolve_path(pattern: str):
-    env = dict(os.environ)
-    env.update({"VNPY_TEMP": str(TEMP_DIR)})
-    return pattern.format(**env)
+
+def extract_vt_symbol(vt_symbol: str):
+    """
+    :return: (symbol, exchange)
+    """
+    symbol, exchange = vt_symbol.split('.')
+    return symbol, exchange
+
+
+def generate_vt_symbol(symbol: str, exchange: "Exchange"):
+    return f'{symbol}.{exchange.value}'
 
 
 def _get_trader_dir(temp_name: str):