This step calculates checksums for one or more fields in the input stream and adds this to the output as a new field.
为数据流输入的列计算校验码，并将输出作为新的一列。
wiki中介绍：http://wiki.pentaho.com/display/EAI/Add+a+checksum
Option | Description |
|---|---|
Step name | Name of the step. Note: This name has to be unique in a single transformation. |
Type | The type of checksum that needs to be calculated. These are the types that are available:
|
Result field | The name of the result field containing the checksum |
Fields used in the checksum | The names of the fields to include in the checksum calculation. |
注意，双击控件后，可以看到各种设置项。result field为新列的名称，一定要写。
这时候看到compatibility mode选项，打钩后，字段就会变得紧凑，不定长。默认为不选，是32位长的字段！
我为了比较字段，所以用定长。
如果想知道区别，做测试：
