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Diffstat (limited to 'guides/source/active_record_migrations.md')
| -rw-r--r-- | guides/source/active_record_migrations.md | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/guides/source/active_record_migrations.md b/guides/source/active_record_migrations.md index cd6b7fdd67..f914122242 100644 --- a/guides/source/active_record_migrations.md +++ b/guides/source/active_record_migrations.md @@ -247,6 +247,7 @@ end ``` This migration will create a `user_id` column and appropriate index. +For more `add_reference` options, visit the [API documentation](http://api.rubyonrails.org/classes/ActiveRecord/ConnectionAdapters/SchemaStatements.html#method-i-add_reference). There is also a generator which will produce join tables if `JoinTable` is part of the name: @@ -353,7 +354,14 @@ end ``` will append `ENGINE=BLACKHOLE` to the SQL statement used to create the table -(when using MySQL, the default is `ENGINE=InnoDB`). +(when using MySQL or MariaDB, the default is `ENGINE=InnoDB`). + +Also you can pass the `:comment` option with any description for the table +that will be stored in database itself and can be viewed with database administration +tools, such as MySQL Workbench or PgAdmin III. It's highly recommended to specify +comments in migrations for applications with large databases as it helps people +to understand data model and generate documentation. +Currently only the MySQL and PostgreSQL adapters support comments. ### Creating a Join Table @@ -454,6 +462,7 @@ number of digits after the decimal point. are using a dynamic value (such as a date), the default will only be calculated the first time (i.e. on the date the migration is applied). * `index` Adds an index for the column. +* `comment` Adds a comment for the column. Some adapters may support additional options; see the adapter specific API docs for further information. @@ -970,7 +979,7 @@ this, then you should set the schema format to `:sql`. Instead of using Active Record's schema dumper, the database's structure will be dumped using a tool specific to the database (via the `db:structure:dump` rails task) into `db/structure.sql`. For example, for PostgreSQL, the `pg_dump` -utility is used. For MySQL, this file will contain the output of +utility is used. For MySQL and MariaDB, this file will contain the output of `SHOW CREATE TABLE` for the various tables. Loading these schemas is simply a question of executing the SQL statements they |