[英]Django unable to migrate PostgreSQL: constraint X of relation Y does not exist
我正在尝试在PostgreSQL 9.6.5数据库上运行Django 1.11迁移,但遇到了奇怪的错误:
Applying myapp.0011_auto_20171130_1807...Traceback (most recent call last):
File "manage.py", line 9, in <module>
execute_from_command_line(sys.argv)
File "/usr/local/myproject/.env/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 364, in execute_from_command_line
utility.execute()
File "/usr/local/myproject/.env/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 356, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/usr/local/myproject/.env/local/lib/python2.7/site-packages/django/core/management/base.py", line 283, in run_from_argv
self.execute(*args, **cmd_options)
File "/usr/local/myproject/.env/local/lib/python2.7/site-packages/django/core/management/base.py", line 330, in execute
output = self.handle(*args, **options)
File "/usr/local/myproject/.env/local/lib/python2.7/site-packages/django/core/management/commands/migrate.py", line 204, in handle
fake_initial=fake_initial,
File "/usr/local/myproject/.env/local/lib/python2.7/site-packages/django/db/migrations/executor.py", line 115, in migrate
state = self._migrate_all_forwards(state, plan, full_plan, fake=fake, fake_initial=fake_initial)
File "/usr/local/myproject/.env/local/lib/python2.7/site-packages/django/db/migrations/executor.py", line 145, in _migrate_all_forwards
state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial)
File "/usr/local/myproject/.env/local/lib/python2.7/site-packages/django/db/migrations/executor.py", line 244, in apply_migration
state = migration.apply(state, schema_editor)
File "/usr/local/myproject/.env/local/lib/python2.7/site-packages/django/db/migrations/migration.py", line 129, in apply
operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
File "/usr/local/myproject/.env/local/lib/python2.7/site-packages/django/db/migrations/operations/models.py", line 536, in database_forwards
getattr(new_model._meta, self.option_name, set()),
File "/usr/local/myproject/.env/local/lib/python2.7/site-packages/django/db/backends/base/schema.py", line 349, in alter_unique_together
self._delete_composed_index(model, fields, {'unique': True}, self.sql_delete_unique)
File "/usr/local/myproject/.env/local/lib/python2.7/site-packages/django/db/backends/base/schema.py", line 380, in _delete_composed_index
self.execute(self._delete_constraint_sql(sql, model, constraint_names[0]))
File "/usr/local/myproject/.env/local/lib/python2.7/site-packages/django/db/backends/base/schema.py", line 120, in execute
cursor.execute(sql, params)
File "/usr/local/myproject/.env/local/lib/python2.7/site-packages/django/db/backends/utils.py", line 65, in execute
return self.cursor.execute(sql, params)
File "/usr/local/myproject/.env/local/lib/python2.7/site-packages/django/db/utils.py", line 94, in __exit__
six.reraise(dj_exc_type, dj_exc_value, traceback)
File "/usr/local/myproject/.env/local/lib/python2.7/site-packages/django/db/backends/utils.py", line 65, in execute
return self.cursor.execute(sql, params)
django.db.utils.ProgrammingError: constraint "idx_32269_myapp_mymodel_title_333195ae82ac2107_uniq" of relation "myapp_mymodel" does not exist
迁移正在将唯一合同从包括一列更改为两列。 很简单 在创建新索引之前,它需要销毁旧索引“ idx_32269_myapp_mymodel_title_333195ae82ac2107_uniq”。 但是,它失败了,因为它认为旧的不存在。
因此,我使用pgAdminIII连接到数据库并检查了该表,并且与错误消息相反,该表确实具有名为idx_32269_myapp_mymodel_title_333195ae82ac2107_uniq
的索引。
我以为Django使用的连接参数可能略有不同,并且正在连接到其他数据库? 让我们尝试从Django dbshell内部对其进行检查。 因此,我开始了manage.py dbshell
并运行:
SELECT *
FROM pg_stat_all_indexes
WHERE indexrelname='idx_32269_myapp_mymodel_title_333195ae82ac2107_uniq';
它返回了一行。
为什么Django在迁移期间看不到该索引,即使该索引确实存在于数据库中?
原来的问题是,我使用pgloader工具将数据库从MySQL转换为PostgreSQL,并且该工具通过在PostgreSQL中将它们创建为索引来转换约束,而Django PG后端将它们创建为约束。 因此,在运行迁移时,它仅查找约束,而找不到约束。
我通过删除索引并将其重新创建为真正的约束来解决此问题:
DROP INDEX idx_32269_myapp_mymodel_title_333195ae82ac2107_uniq;
ALTER TABLE public.myapp_mymodel ADD CONSTRAINT idx_32269_myapp_mymodel_title_333195ae82ac2107_uniq UNIQUE(title);
此后,Django迁移正常运行。
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