From cfe731c26bcf583d4fa99a4ac67bb3963ccfc011 Mon Sep 17 00:00:00 2001 From: jordanstaub Date: Mon, 28 May 2012 20:53:04 -0400 Subject: Added information regarding the schema_migrations table in Active Record Migrations guide. --- guides/source/migrations.textile | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'guides/source') diff --git a/guides/source/migrations.textile b/guides/source/migrations.textile index 52dba76e68..909815d6d7 100644 --- a/guides/source/migrations.textile +++ b/guides/source/migrations.textile @@ -8,8 +8,14 @@ production machines next time you deploy. Active Record tracks which migrations have already been run so all you have to do is update your source and run +rake db:migrate+. Active Record will work out -which migrations should be run. It will also update your +db/schema.rb+ file to -match the structure of your database. +which migrations should be run by checking the hidden +schema_mirgrations+ database +table, which is created automatically after the initial invocaton of +rake db:migrate+. ++schema_migrations+ contains a sole column named +versions+ that holds the time +stamps that are preappended to generated Active Record migrations. Each time stamp +contained in +schema_migrations+ indicate that the migration associated with the +time stamp has previously been invoked, and does not need to be run on future ++rake db:migrate+ invocations. Active Record will also update your +db/schema.rb+ +file to match the up-to-date structure of your database. Migrations also allow you to describe these transformations using Ruby. The great thing about this is that (like most of Active Record's functionality) it -- cgit v1.2.3