Add support for interleaving migrations by storing which migrations have run in the new schema_migrations table. Closes #11493 [jordi]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@9244 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

1 files changed, 29 insertions, 21 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
index 393d5c130e..c986f0c6f1 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
@@ -232,33 +232,41 @@ module ActiveRecord
 
       # Should not be called normally, but this operation is non-destructive.
       # The migrations module handles this automatically.
-      def initialize_schema_information(current_version=0)
-        begin
-          execute "CREATE TABLE #{quote_table_name(ActiveRecord::Migrator.schema_info_table_name)} (version #{type_to_sql(:string)})"
-          execute "INSERT INTO #{quote_table_name(ActiveRecord::Migrator.schema_info_table_name)} (version) VALUES(#{current_version})"
-        rescue ActiveRecord::StatementInvalid
-          # Schema has been initialized, make sure version is a string
-          version_column = columns(:schema_info).detect { |c| c.name == "version" }
-          
-          # can't just alter the table, since SQLite can't deal
-          unless version_column.type == :string
-            version = ActiveRecord::Migrator.current_version
-            execute "DROP TABLE #{quote_table_name(ActiveRecord::Migrator.schema_info_table_name)}"
-            initialize_schema_information(version)
+      def initialize_schema_migrations_table
+        sm_table = ActiveRecord::Migrator.schema_migrations_table_name
+
+        unless tables.detect { |t| t == sm_table }
+          create_table(sm_table, :id => false) do |schema_migrations_table|
+            schema_migrations_table.column :version, :string, :null => false
           end
-        end
-      end
+          add_index sm_table, :version, :unique => true,
+            :name => 'unique_schema_migrations'
+
+          # Backwards-compatibility: if we find schema_info, assume we've
+          # migrated up to that point:
+          si_table = Base.table_name_prefix + 'schema_info' + Base.table_name_suffix
+
+          if tables.detect { |t| t == si_table }
 
-      def dump_schema_information #:nodoc:
-        begin
-          if (current_schema = ActiveRecord::Migrator.current_version) > 0
-            return "INSERT INTO #{quote_table_name(ActiveRecord::Migrator.schema_info_table_name)} (version) VALUES (#{current_schema})" 
+            old_version = select_value("SELECT version FROM #{quote_table_name(si_table)}").to_i
+            assume_migrated_upto_version(old_version)
+            drop_table(si_table)
           end
-        rescue ActiveRecord::StatementInvalid 
-          # No Schema Info
         end
       end
 
+      def assume_migrated_upto_version(version)
+        sm_table = quote_table_name(ActiveRecord::Migrator.schema_migrations_table_name)
+        migrated = select_values("SELECT version FROM #{sm_table}").map(&:to_i)
+        versions = Dir['db/migrate/[0-9]*_*.rb'].map do |filename|
+          filename.split('/').last.split('_').first.to_i
+        end
+
+        execute "INSERT INTO #{sm_table} (version) VALUES ('#{version}')" unless migrated.include?(version.to_i)
+        (versions - migrated).select { |v| v < version.to_i }.each do |v|
+          execute "INSERT INTO #{sm_table} (version) VALUES ('#{v}')"
+        end
+      end
 
       def type_to_sql(type, limit = nil, precision = nil, scale = nil) #:nodoc:
         if native = native_database_types[type]