This example shows a simple map/reduce job that reads from an accumulo table and writes back into that table.
To run this example you will need some data in a table. The following will put a trivial amount of data into accumulo using the accumulo shell:
$ accumulo shell username@instance> createtable rowhash username@instance> insert a-row cf cq value username@instance> insert b-row cf cq value username@instance> quit
The RowHash class will insert a hash for each row in the database if it contains a specified colum. Here's how you run the map/reduce job
$ ./bin/runmr mapreduce.RowHash -t rowhash --column cf:cq
Now we can scan the table and see the hashes:
$ accumulo shell username@instance> scan -t rowhash a-row cf:cq [] value a-row cf-HASHTYPE:cq-MD5BASE64 [] IGPBYI1uC6+AJJxC4r5YBA== b-row cf:cq [] value b-row cf-HASHTYPE:cq-MD5BASE64 [] IGPBYI1uC6+AJJxC4r5YBA== username@instance>