在 RedShift 中使用 Django 多数据库

Question

我正在尝试使用 Django 多数据库配置，将 MYSQL 作为我的默认数据库，将 redshift 作为我的分析数据库。我的配置有时看起来像这样：

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,
    }
}

当我尝试迁移我的分析应用程序时，使用以下命令

python manage.py migrate analytics --database analytics

我看到以下错误：

  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".

关于如何解决这个问题有什么想法吗？我正在使用 Django==1.7.9 和 psycopg2==2.6.1

Answer 1

具体问题是：Django想创建一个migration-management table，主键是serial来跟踪迁移历史。 Redshift 不支持。

不过，该方法更普遍的问题是您并不真正希望在 Redshift 数据库上进行 Django 样式的迁移（参见 How to change table schema after created in Redshift? 之类的内容）。 Redshift 适用于大型数据库，更改其架构可能是一项重量级的工作。

所以，答案是：不要将 Django 迁移与 redshift 一起使用。 Syncdb 可能没问题，可以初始化您的 tables，但之后您将需要手动管理架构。不要在其模型用于 Redshift 的应用程序中创建 migrations__init__.py 文件。

Related/duplicate 这里有问题：

Column 'django_migrations.id' has unsupported type 'serial' [ with Amazon Redshift]
Error : django_migrations.id has unsupported type "serial" with Amazon Redshift

在 RedShift 中使用 Django 多数据库

Using Django Multiple Databases with RedShift

python

django

django-models

amazon-redshift