Django：将数据从 SQLite 移动到 PostgreSQL

Posted 2023-02-24

【中文标题】Django：将数据从 SQLite 移动到 PostgreSQL

【英文标题】：Django: Moving data from SQLite to PostgreSQL

【发布时间】：2018-05-23 00:37:27

【问题描述】：

我最近继承了一个使用 Django 编写的 webapp 的生产代码库。到目前为止，项目使用的数据库一直是默认的 SQLite3 数据库，但现在使用该应用程序的人越来越多，迁移到 Postgres 是必要的。

我已经能够使用运行良好的项目设置一个空的 postgres 数据库。我遇到的问题是将数据从旧项目移动到新项目。我可以跑 python manage.py dumpdata --natural-foreign > dump.json 转储数据，效果很好，但是当我在 settings.py 中切换到 postgres 并运行时 python manage.py loaddata dump.json 我收到以下错误：

Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/mnt/d/Code/MCJobTrack/_VENV/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 338, in execute_from_command_line
    utility.execute()
  File "/mnt/d/Code/MCJobTrack/_VENV/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 330, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/mnt/d/Code/MCJobTrack/_VENV/local/lib/python2.7/site-packages/django/core/management/base.py", line 390, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/mnt/d/Code/MCJobTrack/_VENV/local/lib/python2.7/site-packages/django/core/management/base.py", line 441, in execute
    output = self.handle(*args, **options)
  File "/mnt/d/Code/MCJobTrack/_VENV/local/lib/python2.7/site-packages/django/core/management/commands/loaddata.py", line 60, in handle
    self.loaddata(fixture_labels)
  File "/mnt/d/Code/MCJobTrack/_VENV/local/lib/python2.7/site-packages/django/core/management/commands/loaddata.py", line 90, in loaddata
    self.load_label(fixture_label)
  File "/mnt/d/Code/MCJobTrack/_VENV/local/lib/python2.7/site-packages/django/core/management/commands/loaddata.py", line 147, in load_label
    obj.save(using=self.using)
  File "/mnt/d/Code/MCJobTrack/_VENV/local/lib/python2.7/site-packages/django/core/serializers/base.py", line 173, in save
    models.Model.save_base(self.object, using=using, raw=True)
  File "/mnt/d/Code/MCJobTrack/_VENV/local/lib/python2.7/site-packages/django/db/models/base.py", line 738, in save_base
    updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)
  File "/mnt/d/Code/MCJobTrack/_VENV/local/lib/python2.7/site-packages/django/db/models/base.py", line 803, in _save_table
    forced_update)
  File "/mnt/d/Code/MCJobTrack/_VENV/local/lib/python2.7/site-packages/django/db/models/base.py", line 853, in _do_update
    return filtered._update(values) > 0
  File "/mnt/d/Code/MCJobTrack/_VENV/local/lib/python2.7/site-packages/django/db/models/query.py", line 580, in _update
    return query.get_compiler(self.db).execute_sql(CURSOR)
  File "/mnt/d/Code/MCJobTrack/_VENV/local/lib/python2.7/site-packages/django/db/models/sql/compiler.py", line 1062, in execute_sql
    cursor = super(SQLUpdateCompiler, self).execute_sql(result_type)
  File "/mnt/d/Code/MCJobTrack/_VENV/local/lib/python2.7/site-packages/django/db/models/sql/compiler.py", line 840, in execute_sql
    cursor.execute(sql, params)
  File "/mnt/d/Code/MCJobTrack/_VENV/local/lib/python2.7/site-packages/django/db/backends/utils.py", line 79, in execute
    return super(CursorDebugWrapper, self).execute(sql, params)
  File "/mnt/d/Code/MCJobTrack/_VENV/local/lib/python2.7/site-packages/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
  File "/mnt/d/Code/MCJobTrack/_VENV/local/lib/python2.7/site-packages/django/db/utils.py", line 97, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File "/mnt/d/Code/MCJobTrack/_VENV/local/lib/python2.7/site-packages/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
django.db.utils.IntegrityError: Problem installing fixture '/mnt/d/Code/MCJobTrack/jobtrack_project/dump.json': Could not load contenttypes.ContentType(pk=15): duplicate key value violates unique constraint "django_content_type_app_label_45f3b1d93ec8c61c_uniq"
DETAIL:  Key (app_label, model)=(jobtrack, purchaseorder) already exists.

到目前为止我已经尝试过：

在 dbshel​​l 中运行 TRUNCATE django_content_type RESTART IDENTITY CASCADE; 转储数据时排除内容类型。 （我收到错误 django.core.serializers.base.DeserializationError: Problem installing fixture '/mnt/d/Code/MCJobTrack/jobtrack_project/dump_no_contenttypes.json': ContentType matching query does not exist.） Resetting the primary key sequence 转储数据时使用 --natural-primary 标签

任何帮助将不胜感激。

【参考方案1】：

您可能还需要使用--natural-primary，以便不将内容类型的主键导出到夹具：

python manage.py dumpdata --natural-foreign --natural-primary > dump.json

【讨论】：

试过了：运行 loaddata 现在会产生错误jobtrack.models.DoesNotExist: Problem installing fixture '/mnt/d/Code/MCJobTrack/jobtrack_project/dump.json': Employee matching query does not exist.

【参考方案2】：

原来我需要做两件事：

使用 --natural-primary、--natural-foreign 和 -e 转储数据 内容类型 Have loaddata ignore post_save signals

加载数据仍然需要很长时间，但它可以工作。