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From paul-rogers <...@git.apache.org>
Subject [GitHub] drill pull request #840: DRILL-5517: Size-aware set methods in value vectors
Date Fri, 30 Jun 2017 01:59:12 GMT
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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