What is the difference between rake db:schema:load and migrations?

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Rake db:schema:load and migrations are both database management tools used in Ruby on Rails applications. However, they have some key differences.

1. Purpose:

rake db:schema:load is used to create database schema from the schema.rb file. It creates tables, indexes, and other database objects based on schema.rb file, which is mainly used in the testing environment.

Whereas, migrations is used to modify the database schema over time by creating, modifying or deleting tables, columns, or indexes. This is useful in the development and production environments where the database schema needs to be managed efficiently.

1. Database Compatibility:

rake db:schema:load is only compatible with databases that support SQL, which includes databases like MySQL, PostgreSQL and SQLite.

On the other hand, migrations is compatible with any database that is supported by ActiveRecord.

1. Execution process:

rake db:schema:load executes the “schema” file of the database in a single step, which can be faster than running many individual migrations to prepare the database.

Whereas, migrations is executed as a series of steps that are sequentially applied to the database. This process allows for version control of the database schema, making it easier to manage changes over time.

In summary, rake db:schema:load is used mainly for testing and can quickly create the database schema from the schema.rb file, while migrations is used to manage changes in the database schema over time, which is essential in development and production environments.