Github user paul-rogers commented on a diff in the pull request: https://github.com/apache/drill/pull/840#discussion_r124950905 --- Diff: exec/vector/src/main/java/org/apache/drill/exec/vector/VectorUtils.java --- @@ -0,0 +1,56 @@ +/* + * 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. + */ +package org.apache.drill.exec.vector; + +public class VectorUtils { + + /** + * Vectors cannot be any larger than the Netty memory allocation + * block size. + */ + + private static final int ABSOLUTE_MAX_SIZE = 16 * 1024 * 1024; + private static final int ABSOLUTE_MIN_SIZE = 16 * 1024; --- End diff -- This code allows a boot-time option to limit maximum vector size. I thought it would be handy for testing, but turned out not to be necessary, so I might remove it. To prevent failures when the value is set wrong, I clamped the value to some minimum and maximum. The maximum is set by the Netty block size. The minimum I just made up: seems if we limit vector size to much smaller than 16 K we'd be unlikely to make progress. Added a comment to clarify.
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