diff --git a/doc.go b/doc.go
index 371f4b31..4ebb178d 100644
--- a/doc.go
+++ b/doc.go
@@ -13,10 +13,34 @@ First, we should new a engine for a database
 Method NewEngine's parameters is the same as sql.Open. It depends
 drivers' implementation. Generally, one engine is enough.
 
-engine.Get(...)
-engine.Insert(...)
-engine.Find(...)
-engine.Iterate(...)
-engine.Delete(...)
+There are 7 major methods and many helpful methods to use to operate database.
+
+1. Insert one or multipe records to database
+
+	engine.Insert(...)
+
+2. Query one record from database
+
+	engine.Get(...)
+
+3. Query multiple records from database
+
+	engine.Find(...)
+
+4. Query multiple records and record by record handle
+
+	engine.Iterate(...)
+
+5. Update one or more records
+
+	engine.Update(...)
+
+6. Delete one or more records
+
+	engine.Delete(...)
+
+7. Count records
+
+	engine.Count(...)
 */
 package xorm
diff --git a/docs/QuickStart.md b/docs/QuickStart.md
index 5dee8938..53f564e1 100644
--- a/docs/QuickStart.md
+++ b/docs/QuickStart.md
@@ -391,6 +391,9 @@ Having的参数字符串
 * NoAutoTime()
 如果此方法执行，则此次生成的语句中Created和Updated字段将不自动赋值为当前时间
 
+* NoCache()
+如果此方法执行，则此次生成的语句则在非缓存模式下执行
+
 * UseBool(...string)
 当从一个struct来生成查询条件或更新字段时，xorm会判断struct的field是否为0,"",nil，如果为以上则不当做查询条件或者更新内容。因为bool类型只有true和false两种值，因此默认所有bool类型不会作为查询条件或者更新字段。如果可以使用此方法，如果默认不传参数，则所有的bool字段都将会被使用，如果参数不为空，则参数中指定的为字段名，则这些字段对应的bool值将被使用。
 
diff --git a/engine.go b/engine.go
index 8d479edb..2658cab9 100644
--- a/engine.go
+++ b/engine.go
@@ -37,6 +37,8 @@ type dialect interface {
 	GetIndexes(tableName string) (map[string]*Index, error)
 }
 
+// Engine is the major struct of xorm, it means a database manager.
+// Commonly, an application only need one engine
 type Engine struct {
 	Mapper         IMapper
 	TagIdentifier  string
@@ -122,7 +124,7 @@ func (engine *Engine) NoCache() *Session {
 // Set a table use a special cacher
 func (engine *Engine) MapCacher(bean interface{}, cacher Cacher) {
 	t := rType(bean)
-	engine.AutoMapType(t)
+	engine.autoMapType(t)
 	engine.Tables[t].Cacher = cacher
 }
 
@@ -143,11 +145,6 @@ func (engine *Engine) Close() error {
 	return engine.Pool.Close(engine)
 }
 
-// Test method is deprecated, use Ping() method.
-func (engine *Engine) Test() error {
-	return engine.Ping()
-}
-
 // Ping tests if database is alive.
 func (engine *Engine) Ping() error {
 	session := engine.NewSession()
@@ -184,20 +181,29 @@ func (engine *Engine) LogWarn(contents ...interface{}) {
 	}
 }
 
-// execute sql
+// Sql method let's you manualy write raw sql and operate
+// For example:
+//
+// 		engine.Sql("select * from user").Find(&users)
+//
+// This	code will execute "select * from user" and set the records to users
+//
 func (engine *Engine) Sql(querystring string, args ...interface{}) *Session {
 	session := engine.NewSession()
 	session.IsAutoClose = true
 	return session.Sql(querystring, args...)
 }
 
+// Default if your struct has "created" or "updated" filed tag, the fields
+// will automatically be filled with current time when Insert or Update
+// invoked. Call NoAutoTime if you dont' want to fill automatically.
 func (engine *Engine) NoAutoTime() *Session {
 	session := engine.NewSession()
 	session.IsAutoClose = true
 	return session.NoAutoTime()
 }
 
-// retrieve all tables, columns, indexes' informations from database.
+// Retrieve all tables, columns, indexes' informations from database.
 func (engine *Engine) DBMetas() ([]*Table, error) {
 	tables, err := engine.dialect.GetTables()
 	if err != nil {
@@ -266,60 +272,82 @@ func (engine *Engine) StoreEngine(storeEngine string) *Session {
 	return session.StoreEngine(storeEngine)
 }
 
+// use for distinct columns. Caution: when you are using cache,
+// distinct will not be cached because cache system need id,
+// but distinct will not provide id
 func (engine *Engine) Distinct(columns ...string) *Session {
 	session := engine.NewSession()
 	session.IsAutoClose = true
 	return session.Distinct(columns...)
 }
 
+// only use the paramters as select or update columns
 func (engine *Engine) Cols(columns ...string) *Session {
 	session := engine.NewSession()
 	session.IsAutoClose = true
 	return session.Cols(columns...)
 }
 
+// Xorm automatically retrieve condition according struct, but
+// if struct has bool field, it will ignore them. So use UseBool
+// to tell system to do not ignore them.
+// If no paramters, it will use all the bool field of struct, or
+// it will use paramters's columns
 func (engine *Engine) UseBool(columns ...string) *Session {
 	session := engine.NewSession()
 	session.IsAutoClose = true
 	return session.UseBool(columns...)
 }
 
+// Only not use the paramters as select or update columns
 func (engine *Engine) Omit(columns ...string) *Session {
 	session := engine.NewSession()
 	session.IsAutoClose = true
 	return session.Omit(columns...)
 }
 
+// This method will generate "column IN (?, ?)"
 func (engine *Engine) In(column string, args ...interface{}) *Session {
 	session := engine.NewSession()
 	session.IsAutoClose = true
 	return session.In(column, args...)
 }
 
+// Temporarily change the Get, Find, Update's table
 func (engine *Engine) Table(tableNameOrBean interface{}) *Session {
 	session := engine.NewSession()
 	session.IsAutoClose = true
 	return session.Table(tableNameOrBean)
 }
 
+// This method will generate "LIMIT start, limit"
 func (engine *Engine) Limit(limit int, start ...int) *Session {
 	session := engine.NewSession()
 	session.IsAutoClose = true
 	return session.Limit(limit, start...)
 }
 
+// Method Desc will generate "ORDER BY column1 DESC, column2 DESC"
+// This will
 func (engine *Engine) Desc(colNames ...string) *Session {
 	session := engine.NewSession()
 	session.IsAutoClose = true
 	return session.Desc(colNames...)
 }
 
+// Method Asc will generate "ORDER BY column1 DESC, column2 Asc"
+// This method can chainable use.
+//
+//		engine.Desc("name").Asc("age").Find(&users)
+//		// SELECT * FROM user ORDER BY name DESC, age ASC
+//
 func (engine *Engine) Asc(colNames ...string) *Session {
 	session := engine.NewSession()
 	session.IsAutoClose = true
 	return session.Asc(colNames...)
 }
 
+// Method OrderBy will generate "ORDER BY order"
 func (engine *Engine) OrderBy(order string) *Session {
 	session := engine.NewSession()
 	session.IsAutoClose = true
@@ -345,21 +373,20 @@ func (engine *Engine) Having(conditions string) *Session {
 	return session.Having(conditions)
 }
 
-//
-func (engine *Engine) AutoMapType(t reflect.Type) *Table {
+func (engine *Engine) autoMapType(t reflect.Type) *Table {
 	engine.mutex.Lock()
 	defer engine.mutex.Unlock()
 	table, ok := engine.Tables[t]
 	if !ok {
-		table = engine.MapType(t)
+		table = engine.mapType(t)
 		engine.Tables[t] = table
 	}
 	return table
 }
 
-func (engine *Engine) AutoMap(bean interface{}) *Table {
+func (engine *Engine) autoMap(bean interface{}) *Table {
 	t := rType(bean)
-	return engine.AutoMapType(t)
+	return engine.autoMapType(t)
 }
 
 func (engine *Engine) newTable() *Table {
@@ -371,7 +398,7 @@ func (engine *Engine) newTable() *Table {
 	return table
 }
 
-func (engine *Engine) MapType(t reflect.Type) *Table {
+func (engine *Engine) mapType(t reflect.Type) *Table {
 	table := engine.newTable()
 	table.Name = engine.Mapper.Obj2Table(t.Name())
 	table.Type = t
@@ -395,7 +422,7 @@ func (engine *Engine) MapType(t reflect.Type) *Table {
 				}
 				if (strings.ToUpper(tags[0]) == "EXTENDS") &&
 					(fieldType.Kind() == reflect.Struct) {
-					parentTable := engine.MapType(fieldType)
+					parentTable := engine.mapType(fieldType)
 					for name, col := range parentTable.Columns {
 						col.FieldName = fmt.Sprintf("%v.%v", fieldType.Name(), col.FieldName)
 						table.Columns[name] = col
@@ -540,36 +567,36 @@ func (engine *Engine) MapType(t reflect.Type) *Table {
 }
 
 // Map a struct to a table
-func (engine *Engine) Map(beans ...interface{}) (e error) {
+func (engine *Engine) mapping(beans ...interface{}) (e error) {
 	engine.mutex.Lock()
 	defer engine.mutex.Unlock()
 	for _, bean := range beans {
 		t := rType(bean)
-		engine.Tables[t] = engine.MapType(t)
+		engine.Tables[t] = engine.mapType(t)
 	}
 	return
 }
 
-// Is a table has any reocrd
+// If a table has any reocrd
 func (engine *Engine) IsTableEmpty(bean interface{}) (bool, error) {
 	t := rType(bean)
 	if t.Kind() != reflect.Struct {
 		return false, errors.New("bean should be a struct or struct's point")
 	}
-	engine.AutoMapType(t)
+	engine.autoMapType(t)
 	session := engine.NewSession()
 	defer session.Close()
 	rows, err := session.Count(bean)
 	return rows > 0, err
 }
 
-// Is a table is exist
+// If a table is exist
 func (engine *Engine) IsTableExist(bean interface{}) (bool, error) {
 	t := rType(bean)
 	if t.Kind() != reflect.Struct {
 		return false, errors.New("bean should be a struct or struct's point")
 	}
-	table := engine.AutoMapType(t)
+	table := engine.autoMapType(t)
 	session := engine.NewSession()
 	defer session.Close()
 	has, err := session.isTableExist(table.Name)
@@ -596,7 +623,7 @@ func (engine *Engine) ClearCacheBean(bean interface{}, id int64) error {
 	if t.Kind() != reflect.Struct {
 		return errors.New("error params")
 	}
-	table := engine.AutoMap(bean)
+	table := engine.autoMap(bean)
 	if table.Cacher != nil {
 		table.Cacher.ClearIds(table.Name)
 		table.Cacher.DelBean(table.Name, id)
@@ -611,7 +638,7 @@ func (engine *Engine) ClearCache(beans ...interface{}) error {
 		if t.Kind() != reflect.Struct {
 			return errors.New("error params")
 		}
-		table := engine.AutoMap(bean)
+		table := engine.autoMap(bean)
 		if table.Cacher != nil {
 			table.Cacher.ClearIds(table.Name)
 			table.Cacher.ClearBeans(table.Name)
@@ -620,12 +647,12 @@ func (engine *Engine) ClearCache(beans ...interface{}) error {
 	return nil
 }
 
-// Sync the new struct change to database, this method will automatically add
+// Sync the new struct changes to database, this method will automatically add
 // table, column, index, unique. but will not delete or change anything.
 // If you change some field, you should change the database manually.
 func (engine *Engine) Sync(beans ...interface{}) error {
 	for _, bean := range beans {
-		table := engine.AutoMap(bean)
+		table := engine.autoMap(bean)
 
 		s := engine.NewSession()
 		defer s.Close()
@@ -715,7 +742,7 @@ func (engine *Engine) Sync(beans ...interface{}) error {
 	return nil
 }
 
-func (engine *Engine) UnMap(beans ...interface{}) (e error) {
+func (engine *Engine) unMap(beans ...interface{}) (e error) {
 	engine.mutex.Lock()
 	defer engine.mutex.Unlock()
 	for _, bean := range beans {
@@ -728,7 +755,7 @@ func (engine *Engine) UnMap(beans ...interface{}) (e error) {
 }
 
 // Drop all mapped table
-func (engine *Engine) DropAll() error {
+func (engine *Engine) dropAll() error {
 	session := engine.NewSession()
 	defer session.Close()
 
@@ -781,7 +808,7 @@ func (engine *Engine) DropTables(beans ...interface{}) error {
 	return session.Commit()
 }
 
-func (engine *Engine) CreateAll() error {
+func (engine *Engine) createAll() error {
 	session := engine.NewSession()
 	defer session.Close()
 	return session.CreateAll()
@@ -823,6 +850,7 @@ func (engine *Engine) Delete(bean interface{}) (int64, error) {
 	return session.Delete(bean)
 }
 
+// Get retrieve one record from table
 func (engine *Engine) Get(bean interface{}) (bool, error) {
 	session := engine.NewSession()
 	defer session.Close()
diff --git a/iterator.go b/iterator.go
deleted file mode 100644
index f679ae18..00000000
--- a/iterator.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package xorm
-
-import (
-	"database/sql"
-)
-
-type Iterator struct {
-	session *Session
-	startId int
-	rows    *sql.Rows
-}
-
-func (iter *Iterator) IsValid() bool {
-	return iter.session != nil && iter.rows != nil
-}
-
-/*
-func (iter *Iterator) Next(bean interface{}) (bool, error) {
-	if !iter.IsValid() {
-		return errors.New("iterator is not valied.")
-	}
-	if iter.rows.Next() {
-		iter.rows.Scan(...)
-	}
-}*/
-
-// close the iterator
-func (iter *Iterator) Close() {
-	if iter.rows != nil {
-		iter.rows.Close()
-	}
-	if iter.session != nil && iter.session.IsAutoClose {
-		iter.session.Close()
-	}
-}
diff --git a/session.go b/session.go
index 4622e7b0..e6ed808d 100644
--- a/session.go
+++ b/session.go
@@ -248,7 +248,7 @@ func (session *Session) scanMapIntoStruct(obj interface{}, objMap map[string][]b
 		return errors.New("Expected a pointer to a struct")
 	}
 
-	table := session.Engine.AutoMapType(rType(obj))
+	table := session.Engine.autoMapType(rType(obj))
 
 	for key, data := range objMap {
 		if _, ok := table.Columns[key]; !ok {
@@ -329,7 +329,7 @@ func (session *Session) Exec(sql string, args ...interface{}) (sql.Result, error
 
 // this function create a table according a bean
 func (session *Session) CreateTable(bean interface{}) error {
-	session.Statement.RefTable = session.Engine.AutoMap(bean)
+	session.Statement.RefTable = session.Engine.autoMap(bean)
 
 	err := session.newDb()
 	if err != nil {
@@ -344,7 +344,7 @@ func (session *Session) CreateTable(bean interface{}) error {
 }
 
 func (session *Session) CreateIndexes(bean interface{}) error {
-	session.Statement.RefTable = session.Engine.AutoMap(bean)
+	session.Statement.RefTable = session.Engine.autoMap(bean)
 
 	err := session.newDb()
 	if err != nil {
@@ -366,7 +366,7 @@ func (session *Session) CreateIndexes(bean interface{}) error {
 }
 
 func (session *Session) CreateUniques(bean interface{}) error {
-	session.Statement.RefTable = session.Engine.AutoMap(bean)
+	session.Statement.RefTable = session.Engine.autoMap(bean)
 
 	err := session.newDb()
 	if err != nil {
@@ -450,7 +450,7 @@ func (session *Session) DropTable(bean interface{}) error {
 	if t.Kind() == reflect.String {
 		session.Statement.AltTableName = bean.(string)
 	} else if t.Kind() == reflect.Struct {
-		session.Statement.RefTable = session.Engine.AutoMap(bean)
+		session.Statement.RefTable = session.Engine.autoMap(bean)
 	} else {
 		return errors.New("Unsupported type")
 	}
@@ -715,7 +715,7 @@ func (session *Session) Iterate(bean interface{}, fun IterFunc) error {
 
 	var sql string
 	var args []interface{}
-	session.Statement.RefTable = session.Engine.AutoMap(bean)
+	session.Statement.RefTable = session.Engine.autoMap(bean)
 	if session.Statement.RawSQL == "" {
 		sql, args = session.Statement.genGetSql(bean)
 	} else {
@@ -780,7 +780,7 @@ func (session *Session) Get(bean interface{}) (bool, error) {
 	session.Statement.Limit(1)
 	var sql string
 	var args []interface{}
-	session.Statement.RefTable = session.Engine.AutoMap(bean)
+	session.Statement.RefTable = session.Engine.autoMap(bean)
 	if session.Statement.RawSQL == "" {
 		sql, args = session.Statement.genGetSql(bean)
 	} else {
@@ -871,12 +871,12 @@ func (session *Session) Find(rowsSlicePtr interface{}, condiBean ...interface{})
 	if session.Statement.RefTable == nil {
 		if sliceElementType.Kind() == reflect.Ptr {
 			if sliceElementType.Elem().Kind() == reflect.Struct {
-				table = session.Engine.AutoMapType(sliceElementType.Elem())
+				table = session.Engine.autoMapType(sliceElementType.Elem())
 			} else {
 				return errors.New("slice type")
 			}
 		} else if sliceElementType.Kind() == reflect.Struct {
-			table = session.Engine.AutoMapType(sliceElementType)
+			table = session.Engine.autoMapType(sliceElementType)
 		} else {
 			return errors.New("slice type")
 		}
@@ -1306,7 +1306,7 @@ func (session *Session) innerInsertMulti(rowsSlicePtr interface{}) (int64, error
 	bean := sliceValue.Index(0).Interface()
 	sliceElementType := rType(bean)
 
-	table := session.Engine.AutoMapType(sliceElementType)
+	table := session.Engine.autoMapType(sliceElementType)
 	session.Statement.RefTable = table
 
 	size := sliceValue.Len()
@@ -1538,7 +1538,7 @@ func (session *Session) bytes2Value(col *Column, fieldValue *reflect.Value, data
 			v = x
 			fieldValue.Set(reflect.ValueOf(v))
 		} else if session.Statement.UseCascade {
-			table := session.Engine.AutoMapType(fieldValue.Type())
+			table := session.Engine.autoMapType(fieldValue.Type())
 			if table != nil {
 				x, err := strconv.ParseInt(string(data), 10, 64)
 				if err != nil {
@@ -1656,7 +1656,7 @@ func (session *Session) value2Interface(col *Column, fieldValue reflect.Value) (
 }
 
 func (session *Session) innerInsert(bean interface{}) (int64, error) {
-	table := session.Engine.AutoMap(bean)
+	table := session.Engine.autoMap(bean)
 	session.Statement.RefTable = table
 
 	colNames, args, err := table.genCols(session, bean, false, false)
@@ -1931,7 +1931,7 @@ func (session *Session) Update(bean interface{}, condiBean ...interface{}) (int6
 	var table *Table
 
 	if t.Kind() == reflect.Struct {
-		table = session.Engine.AutoMap(bean)
+		table = session.Engine.autoMap(bean)
 		session.Statement.RefTable = table
 
 		if session.Statement.ColumnStr == "" {
@@ -2078,7 +2078,7 @@ func (session *Session) Delete(bean interface{}) (int64, error) {
 		defer session.Close()
 	}
 
-	table := session.Engine.AutoMap(bean)
+	table := session.Engine.autoMap(bean)
 	session.Statement.RefTable = table
 	colNames, args := buildConditions(session.Engine, table, bean, true,
 		session.Statement.allUseBool, session.Statement.boolColumnMap)
diff --git a/statement.go b/statement.go
index 96841078..10a8492d 100644
--- a/statement.go
+++ b/statement.go
@@ -98,7 +98,7 @@ func (statement *Statement) Table(tableNameOrBean interface{}) {
 	if t.Kind() == reflect.String {
 		statement.AltTableName = tableNameOrBean.(string)
 	} else if t.Kind() == reflect.Struct {
-		statement.RefTable = statement.Engine.AutoMapType(t)
+		statement.RefTable = statement.Engine.autoMapType(t)
 	}
 }
 
@@ -166,7 +166,7 @@ func buildConditions(engine *Engine, table *Table, bean interface{}, includeVers
 					val = t
 				}
 			} else {
-				engine.AutoMapType(fieldValue.Type())
+				engine.autoMapType(fieldValue.Type())
 				if table, ok := engine.Tables[fieldValue.Type()]; ok {
 					pkField := reflect.Indirect(fieldValue).FieldByName(table.PKColumn().FieldName)
 					if pkField.Int() != 0 {
@@ -431,7 +431,7 @@ func (s *Statement) genDropSQL() string {
 }
 
 func (statement Statement) genGetSql(bean interface{}) (string, []interface{}) {
-	table := statement.Engine.AutoMap(bean)
+	table := statement.Engine.autoMap(bean)
 	statement.RefTable = table
 
 	colNames, args := buildConditions(statement.Engine, table, bean, true,
@@ -469,7 +469,7 @@ func (s *Statement) genAddUniqueStr(uqeName string, cols []string) (string, []in
 }
 
 func (statement Statement) genCountSql(bean interface{}) (string, []interface{}) {
-	table := statement.Engine.AutoMap(bean)
+	table := statement.Engine.autoMap(bean)
 	statement.RefTable = table
 
 	colNames, args := buildConditions(statement.Engine, table, bean, true, statement.allUseBool, statement.boolColumnMap)