Apache Accumulo™

Title: Apache Accumulo RowHash Example Notice: Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to you under the Apache License, Version 2.0 (the “License”); you may not use this file except in compliance with the License. You may obtain a copy of the License at . http://www.apache.org/licenses/LICENSE-2.0 . Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an “AS IS” BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

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:

$ ./bin/accumulo shell -u username -p password
Shell - Apache Accumulo Interactive Shell
- version: 1.5.0
- instance name: instance
- instance id: 00000000-0000-0000-0000-000000000000
-
- type 'help' for a list of available commands
-
username@instance> createtable input
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/tool.sh lib/accumulo-examples-simple.jar org.apache.accumulo.examples.simple.mapreduce.RowHash -u user -p passwd -i instance -t input --column cf:cq

Now we can scan the table and see the hashes:

$ ./bin/accumulo shell -u username -p password
Shell - Apache Accumulo Interactive Shell
- version: 1.5.0
- instance name: instance
- instance id: 00000000-0000-0000-0000-000000000000
-
- type 'help' for a list of available commands
-
username@instance> scan -t input
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>