Rails中的汇总迁移 [英] Aggregate migrations in Rails
问题描述
我有数十笔Rails DB迁移，这些迁移是一年来写的.有没有一种方法可以将它们聚合到一个迁移中，这样我就可以看到数据库的完整DDL语句，因为它现在已经存在?我只需要当前的快照，而无需了解我们如何使用它的所有历史记录.
I have several dozens Rails DB migrations which were written over a year. Is there a way to aggregate them to one migration so that I will just see a full DDL statement for the database as it exists now? I just need the current snaphot without all the history of how we got to it.
推荐答案
可以，但是可能不是一个好主意来汇总迁移！
It is possible, but probably not a good idea to aggregate the migrations!
也许会问:
- 您为什么要这样做?
- 您真正需要多长时间迁移一次到VERSION = 0，然后再次备份?
- 是不是真的坏了? (如果没有，那就不要修复它)
我曾经遇到过同样的问题..我最终只是重新排序了迁移，因为架构中的更改导致它不再能够正确地向上/向下迁移.我会犹豫再做一次.
I've had the same problem once.. I ended up just re-ordering my migrations, because changes in the schema caused it to not correctly migrate up/down anymore. I would be hesitant to do that again.
如果您的迁移仅添加字段或索引，则可以将它们与模型的主要迁移结合起来，但是请注意，您不再能够重现旧的情况，例如较旧的DB转储可能与其应兼容的迁移号不兼容-这可能是反对汇总的最大理由...
If you have migrations which just add fields or indexes, then maybe you can combine them with the main migration for the model -- but beware that you can't reproduce old situations anymore, e.g. older DB-dumps may not be compatible with what migration number they should be compatible with -- that is probably the biggest argument against aggregating...
从技术上讲，您可以转储模式，然后直接加载它-这是一种方法:
Technically, you can dump the schema and then load it directly - that is one way:
rake db:schema:dump
然后使用架构转储文件db/schema.rb的内容创建一个新的迁移
then create a single new migration with the contents of the schema dump file db/schema.rb
以下是一些类似的问题:
Here are some similar questions:
P.S .:我发现坚持旧的迁移编号方案非常有用，因为在这种迁移方案中，迁移不使用时间戳-对我来说，效果更好(更容易看出它们的顺序).
P.S.: I found it useful to stick with the old migration numbering scheme, where the migrations do not use timestamps - for me this works better (is easier to see in which order they are).
例如在您的config/application.rb文件中:
e.g. in your config/application.rb file:
config.active_record.timestamped_migrations = false
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