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Diffstat (limited to 'railties/doc/guides/migrations/scheming.txt')
| -rw-r--r-- | railties/doc/guides/migrations/scheming.txt | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/railties/doc/guides/migrations/scheming.txt b/railties/doc/guides/migrations/scheming.txt index 5a2e04cf8c..8290f7116e 100644 --- a/railties/doc/guides/migrations/scheming.txt +++ b/railties/doc/guides/migrations/scheming.txt @@ -33,7 +33,7 @@ end In many ways this is exactly what it is. This file is created by inspecting the database and expressing its structure using `create_table`, `add_index` and so on. Because this is database independent it could be loaded into any database that Active Record supports. This could be very useful if you were to distribute an application that is able to run against multiple databases. -There is however a trade-off: `schema.rb` cannot express database specific items such as foreign key constraints. 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`. +There is however a trade-off: `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 dumped using a tool specific to that database (via the `db:structure:dump` rake task) into `db/#\{RAILS_ENV\}_structure.sql`. For example for postgresql the `pg_dump` utility is used and for mysql this file will contain the output of SHOW CREATE TABLE for the various tables. Loading this schema is simply a question of executing the sql statements contained inside. |