Title: Apache Accumulo MaxMutation Constraints 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 an example of how to limit the size of mutations that will be accepted into a table. Under the default configuration, accumulo does not provide a limitation on the size of mutations that can be ingested. Poorly behaved writers might inadvertently create mutations so large, that they cause the tablet servers to run out of memory. A simple contraint can be added to a table to reject very large mutations.
$ ./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 test_ingest username@instance test_ingest> config -t test_ingest -s table.constraint.1=org.apache.accumulo.examples.simple.constraints.MaxMutationSize username@instance test_ingest>
Now the table will reject any mutation that is larger than 1/256th of the working memory of the tablet server. The following command attempts to ingest a single row with 10000 columns, which exceeds the memory limit. Depending on the amount of Java heap your tserver(s) are given, you may have to increase the number of columns provided to see the failure.
$ ./bin/accumulo org.apache.accumulo.test.TestIngest -i instance -z zookeepers -u username -p password --rows 1 --cols 10000 ERROR : Constraint violates : ConstraintViolationSummary(constrainClass:org.apache.accumulo.examples.simple.constraints.MaxMutationSize, violationCode:0, violationDescription:mutation exceeded maximum size of 188160, numberOfViolatingMutations:1)