Revert "One network trip for the deletion strategy" See #192

This reverts commit 51527a0384.

lib/database_cleaner/active_record/deletion.rb

@@ -3,18 +3,61 @@ require 'active_record/connection_adapters/abstract_adapter'
 require "database_cleaner/generic/truncation"
 require 'database_cleaner/active_record/base'
 require 'database_cleaner/active_record/truncation'
+# This file may seem to have duplication with that of truncation, but by keeping them separate
+# we avoiding loading this code when it is not being used (which is the common case).
 
-module DatabaseCleaner::ActiveRecord
-  class Deletion < Truncation
+module ActiveRecord
+  module ConnectionAdapters
 
-    def clean
-      connection = connection_class.connection
-      connection.disable_referential_integrity do
-        sql = tables_to_truncate(connection).map do |table_name|
-          "DELETE FROM #{connection.quote_table_name(table_name)}"
-        end.join(";")
+    class MysqlAdapter < MYSQL_ADAPTER_PARENT
+      def delete_table(table_name)
+        execute("DELETE FROM #{quote_table_name(table_name)};")
+      end
+    end
 
-        connection.execute sql
+    class Mysql2Adapter < MYSQL2_ADAPTER_PARENT
+      def delete_table(table_name)
+        execute("DELETE FROM #{quote_table_name(table_name)};")
+      end
+    end
+
+    class JdbcAdapter < AbstractAdapter
+      def delete_table(table_name)
+          execute("DELETE FROM #{quote_table_name(table_name)};")
+      end
+    end
+
+    class PostgreSQLAdapter < POSTGRE_ADAPTER_PARENT
+      def delete_table(table_name)
+        execute("DELETE FROM #{quote_table_name(table_name)};")
+      end
+    end
+
+    class SQLServerAdapter < AbstractAdapter
+      def delete_table(table_name)
+        execute("DELETE FROM #{quote_table_name(table_name)};")
+      end
+    end
+
+    class OracleEnhancedAdapter < AbstractAdapter
+      def delete_table(table_name)
+        execute("DELETE FROM #{quote_table_name(table_name)}")
+      end
+    end
+
+  end
+end
+
+
+module DatabaseCleaner::ActiveRecord
+  class Deletion < Truncation
+
+    def clean
+      connection = connection_class.connection
+      connection.disable_referential_integrity do
+        tables_to_truncate(connection).each do |table_name|
+          connection.delete_table table_name
+        end
       end
     end