Where can I get a list of possibilities in migration classes?

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I am new to rails and ruby. I am trying to make a ActiveRecord::Migration to match my wishes, but where can I find documentation for what is possible in a ActiveRecord::Migrat开发者_JAVA技巧ion? I mean how to define field lengths for e.g. string and if null values are allowed or not and how to define/create different indexes?

Thank you Søren

1. TableDefinitions#columns to see what options you can use on creating columns.
2. SchemaStatements for methods that can be used in migration.
3. Migration on RoR Guides.