Django "MigrationSchemaMissing: Unable to create the django_migrations table (no schema has been selected to create in)"

Question

我正在尝试将生产数据库恢复到我的本地计算机，类似于为 Heroku ( https://devcenter.heroku.com/articles/heroku-postgres-import-export) 描述的工作流程。但是，我使用的是 Aptible，它提供了一个 DB tunnel为此目的。

使用 pgAdmin4，我创建了一个“自定义”备份。然后，稍微修改 pgAdmin 命令，我使用

恢复了它

"/Applications/pgAdmin 4.app/Contents/SharedSupport/pg_restore" --host "localhost" --port "5432" --username "postgres" --no-password --dbname "lucy_prod" --verbose "/Users/kurtpeek/lucy-prod-backup-11-june-2018" --clean

我在其中添加了 --clean 选项以在重新创建数据库对象之前删除它们(参见 https://www.postgresql.org/docs/9.2/static/app-pgrestore.html )。

问题是，当我现在尝试 python manage.py migrate 时，出现以下错误:

(venv) Kurts-MacBook-Pro-2:lucy-web kurtpeek$ python manage.py migrate
Traceback (most recent call last):
  File "/Users/kurtpeek/Documents/Dev/lucy2/lucy-web/venv/lib/python3.6/site-packages/django/db/backends/utils.py", line 62, in execute
    return self.cursor.execute(sql)
psycopg2.ProgrammingError: no schema has been selected to create in
LINE 1: CREATE TABLE "django_migrations" ("id" serial NOT NULL PRIMA...
                     ^


The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/Users/kurtpeek/Documents/Dev/lucy2/lucy-web/venv/lib/python3.6/site-packages/django/db/migrations/recorder.py", line 57, in ensure_schema
    editor.create_model(self.Migration)
  File "/Users/kurtpeek/Documents/Dev/lucy2/lucy-web/venv/lib/python3.6/site-packages/django/db/backends/base/schema.py", line 303, in create_model
    self.execute(sql, params or None)
  File "/Users/kurtpeek/Documents/Dev/lucy2/lucy-web/venv/lib/python3.6/site-packages/django/db/backends/base/schema.py", line 120, in execute
    cursor.execute(sql, params)
  File "/Users/kurtpeek/Documents/Dev/lucy2/lucy-web/venv/lib/python3.6/site-packages/django/db/backends/utils.py", line 79, in execute
    return super(CursorDebugWrapper, self).execute(sql, params)
  File "/Users/kurtpeek/Documents/Dev/lucy2/lucy-web/venv/lib/python3.6/site-packages/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
  File "/Users/kurtpeek/Documents/Dev/lucy2/lucy-web/venv/lib/python3.6/site-packages/django/db/utils.py", line 94, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File "/Users/kurtpeek/Documents/Dev/lucy2/lucy-web/venv/lib/python3.6/site-packages/django/utils/six.py", line 685, in reraise
    raise value.with_traceback(tb)
  File "/Users/kurtpeek/Documents/Dev/lucy2/lucy-web/venv/lib/python3.6/site-packages/django/db/backends/utils.py", line 62, in execute
    return self.cursor.execute(sql)
django.db.utils.ProgrammingError: no schema has been selected to create in
LINE 1: CREATE TABLE "django_migrations" ("id" serial NOT NULL PRIMA...
                     ^


During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "manage.py", line 29, in <module>
    execute_from_command_line(sys.argv)
  File "/Users/kurtpeek/Documents/Dev/lucy2/lucy-web/venv/lib/python3.6/site-packages/django/core/management/__init__.py", line 364, in execute_from_command_line
    utility.execute()
  File "/Users/kurtpeek/Documents/Dev/lucy2/lucy-web/venv/lib/python3.6/site-packages/django/core/management/__init__.py", line 356, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/Users/kurtpeek/Documents/Dev/lucy2/lucy-web/venv/lib/python3.6/site-packages/django/core/management/base.py", line 283, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/Users/kurtpeek/Documents/Dev/lucy2/lucy-web/venv/lib/python3.6/site-packages/django/core/management/base.py", line 330, in execute
    output = self.handle(*args, **options)
  File "/Users/kurtpeek/Documents/Dev/lucy2/lucy-web/venv/lib/python3.6/site-packages/django/core/management/commands/migrate.py", line 83, in handle
    executor = MigrationExecutor(connection, self.migration_progress_callback)
  File "/Users/kurtpeek/Documents/Dev/lucy2/lucy-web/venv/lib/python3.6/site-packages/django/db/migrations/executor.py", line 20, in __init__
    self.loader = MigrationLoader(self.connection)
  File "/Users/kurtpeek/Documents/Dev/lucy2/lucy-web/venv/lib/python3.6/site-packages/django/db/migrations/loader.py", line 52, in __init__
    self.build_graph()
  File "/Users/kurtpeek/Documents/Dev/lucy2/lucy-web/venv/lib/python3.6/site-packages/django/db/migrations/loader.py", line 209, in build_graph
    self.applied_migrations = recorder.applied_migrations()
  File "/Users/kurtpeek/Documents/Dev/lucy2/lucy-web/venv/lib/python3.6/site-packages/django/db/migrations/recorder.py", line 65, in applied_migrations
    self.ensure_schema()
  File "/Users/kurtpeek/Documents/Dev/lucy2/lucy-web/venv/lib/python3.6/site-packages/django/db/migrations/recorder.py", line 59, in ensure_schema
    raise MigrationSchemaMissing("Unable to create the django_migrations table (%s)" % exc)
django.db.migrations.exceptions.MigrationSchemaMissing: Unable to create the django_migrations table (no schema has been selected to create in
LINE 1: CREATE TABLE "django_migrations" ("id" serial NOT NULL PRIMA...
                     ^
)

据我了解 MigrationSchemaMissing(Unable to create the django_migrations table (%s) % exc) , 我需要跑

grant usage on schema public to username;
grant create on schema public to username;

但是，用户名应该填什么呢？这应该是 postgres 吗？

这里有一些关于public 模式和search_path 的更多细节:

(venv) Kurts-MacBook-Pro-2:lucy-web kurtpeek$ python manage.py dbshell
psql (10.4)
Type "help" for help.

lucy_prod=> \dn+ public
                        List of schemas
  Name  |  Owner   | Access privileges |      Description       
--------+----------+-------------------+------------------------
 public | postgres |                   | standard public schema
(1 row)

lucy_prod=> SHOW search_path;
   search_path   
-----------------
 "$user", public
(1 row)

更新

通过运行 select current_user; 命令，我确定我当前的用户名为 lucyapp，但是如果我尝试grant usage on schema public 对于这个用户，我得到一个“权限被拒绝”的错误:

lucy_prod=> select current_user;
 current_user 
--------------
 lucyapp
(1 row)

lucy_prod=> grant usage on schema public to lucyapp;
ERROR:  permission denied for schema public
lucy_prod=> grant create on schema public to lucyapp;
ERROR:  permission denied for schema public

Answer 1

这是由于角色对 public 模式的访问问题而发生的。在数据库 shell 中运行此脚本将解决问题。

GRANT ALL ON SCHEMA public TO your_user;
GRANT ALL ON SCHEMA public TO public;

This is for Postgres DB. A similar script can be found for other SQL DB.