Add option to force tables to use default engine (#175)

Author: coding-chimp

lib/lhm.rb

@@ -54,9 +54,9 @@ module Lhm
   def change_table(table_name, options = {}, &block)
     with_flags(options) do
       origin = Table.parse(table_name, connection)
-      invoker = Invoker.new(origin, connection)
+      invoker = Invoker.new(origin, connection, options)
       block.call(invoker.migrator)
-      invoker.run(options)
+      invoker.run
       true
     end
   end

lib/lhm/invoker.rb

@@ -21,9 +21,11 @@ class Invoker
 
     attr_reader :migrator, :connection
 
-    def initialize(origin, connection)
+    def initialize(origin, connection, options = {})
       @connection = connection
-      @migrator = Migrator.new(origin, connection)
+      @migrator = Migrator.new(origin, connection, options)
+      @options = options
+      normalize_options(@options)
     end
 
     def set_session_lock_wait_timeouts
@@ -45,17 +47,16 @@ def set_session_lock_wait_timeouts
       end
     end
 
-    def run(options = {})
-      normalize_options(options)
+    def run
       set_session_lock_wait_timeouts
       migration = @migrator.run
       entangler = Entangler.new(migration, @connection)
 
       entangler.run do
-        options[:verifier] ||= Proc.new { |conn| triggers_still_exist?(conn, entangler) }
-        Chunker.new(migration, @connection, options).run
+        @options[:verifier] ||= Proc.new { |conn| triggers_still_exist?(conn, entangler) }
+        Chunker.new(migration, @connection, @options).run
         raise "Required triggers do not exist" unless triggers_still_exist?(@connection, entangler)
-        if options[:atomic_switch]
+        if @options[:atomic_switch]
           AtomicSwitcher.new(migration, @connection).run
         else
           LockedSwitcher.new(migration, @connection).run

lib/lhm/migrator.rb

@@ -15,12 +15,13 @@ class Migrator
 
     attr_reader :name, :statements, :connection, :conditions, :renames, :origin
 
-    def initialize(table, connection = nil)
+    def initialize(table, connection = nil, options = {})
       @connection = connection
       @origin = table
       @name = table.destination_name
       @statements = []
       @renames = {}
+      @options = options
     end
 
     # Alter a table with a custom statement
@@ -222,6 +223,11 @@ def destination_create
       original    = %{CREATE TABLE `#{ @origin.name }`}
       replacement = %{CREATE TABLE `#{ @origin.destination_name }`}
       stmt = @origin.ddl.gsub(original, replacement)
+
+      if @options[:force_default_engine]
+        stmt = stmt.sub(/ENGINE=\w+\s/, "")
+      end
+
       @connection.execute(tagged(stmt))
 
       Lhm.logger.info("Created destination table #{@origin.destination_name}")

spec/fixtures/myisam_users.ddl

@@ -0,0 +1,10 @@
+CREATE TABLE `myisam_users` (
+  `id` int(11) NOT NULL AUTO_INCREMENT,
+  `reference` int(11) DEFAULT NULL,
+  `username` varchar(255) DEFAULT NULL,
+  `group` varchar(255) DEFAULT 'Superfriends',
+  `created_at` datetime DEFAULT NULL,
+  `comment` varchar(20) DEFAULT NULL,
+  `description` text,
+  PRIMARY KEY (`id`)
+) ENGINE=MyISAM CHARSET=utf8

spec/integration/lhm_spec.rb

@@ -553,6 +553,27 @@
       end
     end
 
+    it 'creates the shadow table with the default engine when the `force_default_engine` option is used' do
+      table_create(:myisam_users)
+
+      engine = select_value("SELECT ENGINE FROM information_schema.TABLES WHERE TABLE_NAME = 'myisam_users'")
+      value(engine).must_equal("MyISAM")
+
+      Lhm.change_table(:myisam_users) do |t|
+        t.add_column(:logins, "INT(12) DEFAULT '0'", algorithm: "COPY")
+      end
+
+      engine = select_value("SELECT ENGINE FROM information_schema.TABLES WHERE TABLE_NAME = 'myisam_users'")
+      value(engine).must_equal("MyISAM")
+
+      Lhm.change_table(:myisam_users, force_default_engine: true) do |t|
+        t.remove_column(:logins)
+      end
+
+      engine = select_value("SELECT ENGINE FROM information_schema.TABLES WHERE TABLE_NAME = 'myisam_users'")
+      value(engine).must_equal("InnoDB")
+    end
+
     describe 'parallel' do
       it 'should perserve inserts during migration' do
         50.times { |n| execute("insert into users set reference = '#{ n }'") }