EN_rowkey generating function example

user defined rowkey generating function, to easy the query.

for example.

one rowkey is designed as following.

md5(userId)+userId(reverse)+cycle(reverse)

we can define one rowkey generating function named billCategoryRowKey, configed in, now we can query like this.

select * from billCategory rowkey is billCategoryRowKey ("2088123456781234_20140401")