奇数耙数据库：迁移输出

为什么rake db:migrate run Execute db:schema:dump我的输出全部搞砸了（显示 SQL）。

看起来像这样：

  ActiveRecord::SchemaMigration Load (0.5ms)  SELECT "schema_migrations".* FROM "schema_migrations"
   (3.7ms)  SELECT t2.oid::regclass::text AS to_table, a1.attname AS column, a2.attname AS primary_key, c.conname AS name, c.confupdtype AS on_update, c.confdeltype AS on_delete
FROM pg_constraint c
JOIN pg_class t1 ON c.conrelid = t1.oid
JOIN pg_class t2 ON c.confrelid = t2.oid
JOIN pg_attribute a1 ON a1.attnum = c.conkey[1] AND a1.attrelid = t1.oid
JOIN pg_attribute a2 ON a2.attnum = c.confkey[1] AND a2.attrelid = t2.oid
JOIN pg_namespace t3 ON c.connamespace = t3.oid
WHERE c.contype = 'f'
  AND t1.relname = 'accounts'
  AND t3.nspname = ANY (current_schemas(false))
ORDER BY c.conname

   (3.2ms)  SELECT t2.oid::regclass::text AS to_table, a1.attname AS column, a2.attname AS primary_key, c.conname AS name, c.confupdtype AS on_update, c.confdeltype AS on_delete
FROM pg_constraint c
JOIN pg_class t1 ON c.conrelid = t1.oid
JOIN pg_class t2 ON c.confrelid = t2.oid
JOIN pg_attribute a1 ON a1.attnum = c.conkey[1] AND a1.attrelid = t1.oid
JOIN pg_attribute a2 ON a2.attnum = c.confkey[1] AND a2.attrelid = t2.oid
JOIN pg_namespace t3 ON c.connamespace = t3.oid
WHERE c.contype = 'f'
  AND t1.relname = 'deliveries'
  AND t3.nspname = ANY (current_schemas(false))
ORDER BY c.conname

   (3.2ms)  SELECT t2.oid::regclass::text AS to_table, a1.attname AS column, a2.attname AS primary_key, c.conname AS name, c.confupdtype AS on_update, c.confdeltype AS on_delete
FROM pg_constraint c
JOIN pg_class t1 ON c.conrelid = t1.oid
JOIN pg_class t2 ON c.confrelid = t2.oid
JOIN pg_attribute a1 ON a1.attnum = c.conkey[1] AND a1.attrelid = t1.oid
JOIN pg_attribute a2 ON a2.attnum = c.confkey[1] AND a2.attrelid = t2.oid
JOIN pg_namespace t3 ON c.connamespace = t3.oid
WHERE c.contype = 'f'
  AND t1.relname = 'posts'
  AND t3.nspname = ANY (current_schemas(false))
ORDER BY c.conname

跟踪显示了这一点：

** Invoke db:migrate (first_time)
** Invoke environment (first_time)
** Execute environment
** Invoke db:load_config (first_time)
** Execute db:load_config
** Execute db:migrate
** Invoke db:_dump (first_time)
** Execute db:_dump
** Invoke db:schema:dump (first_time)
** Invoke environment 
** Invoke db:load_config 
** Execute db:schema:dump

这是在将 Rails 4.1.6 升级到 Rails 4.2.0 后开始的。

为什么会出现这种情况？

我得到这个奇怪的神秘 SQL'ish 输出的原因是因为我的 gemfile 中有 Heroku 的rails_12factor gem，并且没有分组到 :product 中。

解决方案是：

group :production do
  gem 'rails_12factor'
end

and run bundle