在RedShift中使用Django多個數據庫

Question

我試圖使用Django多數據庫配置與MYSQL作為我的默認數據庫和redshift作為我的分析數據庫。 我的配置看起來像這樣：

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'xxxx',
        'USER': 'xxxx',
        'PASSWORD': 'xxxx',
        'HOST': 'localhost',
    },
    'analytics': {
        'NAME': 'analytics',
        'ENGINE': 'django.db.backends.postgresql_psycopg2',
        'USER': 'XXXXXXXXX',
        'PASSWORD': 'XXXXX',
        'HOST': 'XXXXX.us-east-1.redshift.amazonaws.com',
        'PORT': 5439,
    }
}

當我嘗試使用以下命令遷移我的分析應用程序時

python manage.py migrate analytics --database analytics

我看到以下錯誤：

  File "/opt/envs/cinematique/bin/django-admin.py", line 5, in <module>
    management.execute_from_command_line()
  File "/opt/envs/cinematique/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 385, in execute_from_command_line
    utility.execute()
  File "/opt/envs/cinematique/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 377, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/opt/envs/cinematique/local/lib/python2.7/site-packages/django/core/management/base.py", line 288, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/opt/envs/cinematique/local/lib/python2.7/site-packages/django/core/management/base.py", line 338, in execute
    output = self.handle(*args, **options)
  File "/opt/envs/cinematique/local/lib/python2.7/site-packages/django/core/management/commands/migrate.py", line 60, in handle
    return self.show_migration_list(connection, args)
  File "/opt/envs/cinematique/local/lib/python2.7/site-packages/django/core/management/commands/migrate.py", line 308, in show_migration_list
    loader = MigrationLoader(connection, ignore_no_migrations=True)
  File "/opt/envs/cinematique/local/lib/python2.7/site-packages/django/db/migrations/loader.py", line 48, in __init__
    self.build_graph()
  File "/opt/envs/cinematique/local/lib/python2.7/site-packages/django/db/migrations/loader.py", line 183, in build_graph
    self.applied_migrations = recorder.applied_migrations()
  File "/opt/envs/cinematique/local/lib/python2.7/site-packages/django/db/migrations/recorder.py", line 59, in applied_migrations
    self.ensure_schema()
  File "/opt/envs/cinematique/local/lib/python2.7/site-packages/django/db/migrations/recorder.py", line 53, in ensure_schema
    editor.create_model(self.Migration)
  File "/opt/envs/cinematique/local/lib/python2.7/site-packages/django/db/backends/schema.py", line 270, in create_model
    self.execute(sql, params)
  File "/opt/envs/cinematique/local/lib/python2.7/site-packages/django/db/backends/schema.py", line 111, in execute
    cursor.execute(sql, params)
  File "/opt/envs/cinematique/local/lib/python2.7/site-packages/django/db/backends/utils.py", line 81, in execute
    return super(CursorDebugWrapper, self).execute(sql, params)
  File "/opt/envs/cinematique/local/lib/python2.7/site-packages/django/db/backends/utils.py", line 65, in execute
    return self.cursor.execute(sql, params)
  File "/opt/envs/cinematique/local/lib/python2.7/site-packages/django/db/utils.py", line 94, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File "/opt/envs/cinematique/local/lib/python2.7/site-packages/django/db/backends/utils.py", line 65, in execute
    return self.cursor.execute(sql, params)
django.db.utils.NotSupportedError: Column "django_migrations.id" has unsupported type "serial".

有關如何解決此問題的任何想法？ 我使用的是Django==1.7.9和psycopg2==2.6.1

Answer 1

具體問題是：Django希望創建一個帶有serial主鍵的遷移管理表來跟蹤遷移歷史記錄。 Redshift不支持這一點。

但是，該方法的更普遍的問題是，您並不真正想要在Redshift數據庫上進行Django式遷移（請參閱如何在Redshift中創建后更改表模式？ ）。 Redshift適用於大型數據庫，更改它的架構可能是一項重量級工作。

所以答案是：不要使用Redshift的Django遷移。 Syncdb可能沒問題，可以初始化表，但之后您需要手動管理模式。 不要在模型適用於Redshift的應用程序中創建migrations__init__.py文件。

相關/重復問題：

• 列'django_migrations.id'具有不受支持的類型'serial'[與Amazon Redshift]
• 錯誤：django_migrations.id使用Amazon Redshift不支持“serial”類型