rake db:migrate db:reset 和 db:schema:load 的区别 [英] Difference between rake db:migrate db:reset and db:schema:load

问题描述

rake db:migrate 和 rake db:reset 之间的区别在我的脑海中非常清楚.我不明白的是 rake db:schema:load 与前两者有何不同.

The difference between rake db:migrate and rake db:reset is pretty clear in my head. The thing which I don't understand is how rake db:schema:load different from the former two.

只是为了确保我在同一页面上:

Just to be sure that I am on the same page:

• rake db:migrate - 运行尚未运行的迁移.
• rake db:reset - 清除数据库(大概做了一个 rake db:drop + rake db:create + rakedb:migrate) 并在新数据库上运行迁移.

• rake db:migrate - Runs the migrations which haven't been run yet.
• rake db:reset - Clears the database (presumably does a rake db:drop + rake db:create + rake db:migrate) and runs migration on a fresh database.

如果我的理解有误，请帮助澄清.

Please help to clarify, if my understanding has gone wrong.

推荐答案

• db:migrate 运行尚未运行的(单个)迁移.

  • db:migrate runs (single) migrations that have not run yet.

    db:create 创建数据库

    db:drop 删除数据库

    db:schema:load 在现有数据库中按照 schema.rb 创建表和列.这将删除现有数据.

    db:schema:load creates tables and columns within the existing database following schema.rb. This will delete existing data.

    db:setup 执行 db:create、db:schema:load、db:seed

    db:setup does db:create, db:schema:load, db:seed

    db:reset 执行 db:drop、db:setup

    db:reset does db:drop, db:setup

    db:migrate:reset 执行 db:drop、db:create、db:migrate

    db:migrate:reset does db:drop, db:create, db:migrate

    通常，您会在通过新的迁移文件更改架构后使用 db:migrate(这仅在数据库中已有数据时才有意义).db:schema:load 在您设置应用程序的新实例时使用.

    Typically, you would use db:migrate after having made changes to the schema via new migration files (this makes sense only if there is already data in the database). db:schema:load is used when you setup a new instance of your app.

    希望能帮到你.

    rails 3.2.12 更新:

    UPDATE for rails 3.2.12:

    我刚查了源码，现在依赖是这样的:

    I just checked the source and the dependencies are like this now:

    • db:create 为当前环境创建数据库

    • db:create creates the database for the current env

    db:create:all 为所有环境创建数据库

    db:create:all creates the databases for all envs

    db:drop 删除当前环境的数据库

    db:drop drops the database for the current env

    db:drop:all 删除所有环境的数据库

    db:drop:all drops the databases for all envs

    db:migrate 为尚未运行的当前环境运行迁移

    db:migrate runs migrations for the current env that have not run yet

    db:migrate:up 运行一个特定的迁移

    db:migrate:down 回滚一个特定的迁移

    db:migrate:status 显示当前的迁移状态

    db:rollback 回滚上次迁移

    db:forward 将当前模式版本推进到下一个

    db:forward advances the current schema version to the next one

    db:seed(仅)运行 db/seed.rb 文件

    db:seed (only) runs the db/seed.rb file

    db:schema:load 将架构加载到当前环境的数据库中

    db:schema:load loads the schema into the current env's database

    db:schema:dump 转储当前 env 的架构(并且似乎也创建了数据库)

    db:schema:dump dumps the current env's schema (and seems to create the db as well)

    db:setup 运行 db:schema:load, db:seed

    db:setup runs db:schema:load, db:seed

    db:reset 运行 db:drop db:setup

    db:reset runs db:drop db:setup

    db:migrate:redo 运行 (db:migrate:down db:migrate:up) 或 (db:rollback db:migrate) 取决于指定的迁移

    db:migrate:redo runs (db:migrate:down db:migrate:up) or (db:rollback db:migrate) depending on the specified migration

    db:migrate:reset 运行 db:drop db:create db:migrate

    db:migrate:reset runs db:drop db:create db:migrate

    有关更多信息，请查看 https://github.com/rails/rails/blob/v3.2.12/activerecord/lib/active_record/railties/databases.rake(适用于 Rails 3.2.x)和 https://github.com/rails/rails/blob/v4.0.5/activerecord/lib/active_record/railties/databases.rake(适用于 Rails 4.0.x)

    For further information please have a look at https://github.com/rails/rails/blob/v3.2.12/activerecord/lib/active_record/railties/databases.rake (for Rails 3.2.x) and https://github.com/rails/rails/blob/v4.0.5/activerecord/lib/active_record/railties/databases.rake (for Rails 4.0.x)

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