奇数 rake db:migrate 输出答案

【问题标题】：Odd rake db:migrate output奇数 rake db:migrate 输出
【发布时间】：2015-03-10 03:44:53
【问题描述】：

为什么rake db:migrate 运行Execute db:schema:dump 我的输出都搞砸了（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

Trace 显示：

** 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 之后开始的。

为什么会这样？

【问题讨论】：

到底是什么问题？模式转储程序更新 schema.rb 并且所有那些看起来很时髦的查询都用于找出表结构。
@mu 每次我运行 rake db:migrate 时都会发生这种情况......如果迁移是最新的，我预计不会发生任何事情。我不明白为什么我看到这个输出......
它总是以'first_time'运行
@muistooshort 你知道是什么导致它像这样转储架构吗？
不是我的头顶。我使用structure.sql，因为我的数据库中有各种ActiveRecord 无法理解的东西。为什么这是个问题？ “我的输出都搞砸了”是什么意思？

标签： ruby-on-rails ruby rake rails-activerecord

【解决方案1】：

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 :production。

解决办法是：

group :production do
  gem 'rails_12factor'
end

然后运行bundle

【讨论】：

【解决方案2】：

升级到 Rails 4.2.1 后我遇到了同样的问题，阻止了我通过 Codeship 进行迁移部署，它期望来自 rake db:migrate 的非常特殊的输出认为推送成功。

在config/environments/production.rb 中设置config.log_level = :info 为我解决了这个问题，大概是因为:debug 级别的日志级别过于冗长。

【讨论】：

【解决方案3】：

This discussion 为我解决了“奇怪”的输出：
只需在您的环境配置中将dump_schema_after_migration 设置为false，如下所示：

/config/environments/development.rb

Application.configure do
  ...
  dump_schema_after_migration = false
  ...
end

编辑
在大多数情况下，这不是您想要做的，因为您需要在版本控制中包含 schema.rb。

【讨论】：