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update guide: db:structure:dump produces structure.sql now

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Vijay Dev 2011-11-18 01:17:21 +05:30
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railties/guides/source/migrations.textile
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@ -658,7 +658,7 @@ In many ways this is exactly what it is. This file is created by inspecting the
There is however a trade-off: +db/schema.rb+ cannot express database specific items such as foreign key constraints, triggers, or stored procedures. While in a migration you can execute custom SQL statements, the schema dumper cannot reconstitute those statements from the database. If you are using features like 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+ Rake task) into +db/#{Rails.env}_structure.sql+. For example, for the PostgreSQL RDBMS, the +pg_dump+ utility is used. For MySQL, 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 contain. By definition, this will create a perfect copy of the database's structure. Using the +:sql+ schema format will, however, prevent loading the schema into a RDBMS other than the one used to create it.
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+ Rake task) into +db/structure.sql+. For example, for the PostgreSQL RDBMS, the +pg_dump+ utility is used. For MySQL, 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 contain. By definition, this will create a perfect copy of the database's structure. Using the +:sql+ schema format will, however, prevent loading the schema into a RDBMS other than the one used to create it.
h4. Schema Dumps and Source Control