在 RedShift 中使用 Django 多个数据库

编程入门行业动态更新时间:2024-10-20 19:01:18

本文介绍了在 RedShift 中使用 Django 多个数据库的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！问题描述

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

I am trying to use an Django multiple database configuration with MYSQL as my default database and redshift as my analytics database. My configuration looks sometime like this:

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', 'PORT': 5439, } }

当我尝试迁移我的分析应用程序时，使用以下命令

When I try to migrate my analytics app, using the following command

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".

有关如何解决此问题的任何想法?我正在使用 Django==1.7.9 和 psycopg2==2.6.1

Any ideas on how to resolve this issue? I am using Django==1.7.9 and psycopg2==2.6.1

推荐答案

具体问题是:Django 想要创建一个带有 serial 主键的迁移管理表来跟踪迁移历史.Redshift 不支持.

The specific problem is: Django wants to create a migration-management table with a serial primary key to track migration history. Redshift doesn't support that.

不过，这种方法更普遍的问题是，您并不真的希望在 Redshift 数据库上进行 Django 风格的迁移(参见在 Redshift 中创建后如何更改表架构?).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.

The more general problem with the approach, though, is that you don't really want Django-style migrations on a Redshift database (see stuff like How to change table schema after created in Redshift?). Redshift is meant for huge databases and changing it's schema can be a heavyweight job.

所以，答案是:不要在 redshift 中使用 Django 迁移.Syncdb 可能没问题，可以初始化您的表，但之后您将需要手动管理架构.不要在模型适用于 Redshift 的应用中创建 migrations__init__.py 文件.

So, the answer is: don't use Django migrations with redshift. Syncdb might be ok, to initialize your tables, but after that you will need to manage the schema manually. Don't create a migrations__init__.py file in an app whose models are intended for Redshift.

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