kettle控件 add a checksum

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: CRC32 : 32-bit Cyclic Redundancy Check : http://en.wikipedia.org/wiki/Cyclic_redundancy_check ADLER 32 : Checksum algorithm by Mark Adler: http://en.wikipedia.org/wiki/Adler-32 MD5 : Message Digest algorithm 5 : http://en.wikipedia.org/wiki/MD5 SHA-1 : Secure Hash Algorithm 1 : http://en.wikipedia.org/wiki/SHA-1
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. Note: You can use the "Get Fields" button to insert all input fields from previous steps.

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：

 

然后就preview rows，就可以看出两种结果的不同