Mailing-List: contact notifications-help@accumulo.apache.org; run by ezmlm
Precedence: bulk
Reply-To: jira@apache.org
Date: Wed, 9 Sep 2015 18:17:46 +0000 (UTC)
From: "ASF GitHub Bot (JIRA)" <jira@apache.org>
To: notifications@accumulo.apache.org
Message-ID: <JIRA.12839708.1435014442000.293155.1441822666725@Atlassian.JIRA>
In-Reply-To: <JIRA.12839708.1435014442000@Atlassian.JIRA>
References: <JIRA.12839708.1435014442000@Atlassian.JIRA>
 <JIRA.12839708.1435014442155@arcas>
Subject: [jira] [Commented] (ACCUMULO-3913) Add per table sampling
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit


    [ https://issues.apache.org/jira/browse/ACCUMULO-3913?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14737338#comment-14737338 ] 

ASF GitHub Bot commented on ACCUMULO-3913:
------------------------------------------

Github user keith-turner commented on a diff in the pull request:

    https://github.com/apache/accumulo/pull/46#discussion_r39077286
  
    --- Diff: core/src/main/java/org/apache/accumulo/core/client/SampleNotPresentException.java ---
    @@ -0,0 +1,32 @@
    +/*
    + * 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.accumulo.core.client;
    +
    +public class SampleNotPresentException extends RuntimeException {
    +
    +  public SampleNotPresentException(Exception e) {
    --- End diff --
    
    fixed in f6f60ad.  I also updated the [Gist](https://gist.github.com/keith-turner/1a073eb032e4d8c448cb)


> Add per table sampling
> ----------------------
>
>                 Key: ACCUMULO-3913
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-3913
>             Project: Accumulo
>          Issue Type: Improvement
>            Reporter: Keith Turner
>             Fix For: 1.8.0
>
>
> I am working on prototyping adding hash based sampling to Accumulo.  I am trying to accomplish the following goals in the prototype.
>   # Have each RFile store a sample per locality group.  Also store the configuration used to generate the sample.
>   # Use sampling functions that ensure the same row columns exist across the samples in all RFiles. Hash mod is a good candidate that gives a random sample that's consistent across files.
>   # Have scanners support scanning RFile's samples sets.  Scan should fail if RFiles have different sample configuration.  Different sampling config implies the RFile's sample sets contain a possibly disjoint set of row columns.
>   # Support generating sample data for RFiles generated for bulk import
>   # Support sample data in the memory map
>   # Support enabling and disabling sampling per table AND configuring a sample function.
> I am currently using the following function in my prototype to determine what data an RFile stores in its sample set.  This code will always select same subset of rows for each RFile's sample set.  I have not yet made the function configurable.
> {code:java}
> public class RowSampler implements Sampler {
>   private HashFunction hasher = Hashing.murmur3_32();
>   @Override
>   public boolean accept(Key k) {
>     ByteSequence row = k.getRowData();
>     HashCode hc = hasher.hashBytes(row.getBackingArray(), row.offset(), row.length());
>     return hc.asInt() % 1009 == 0;
>   }
> }
> {code}
> Although not yet implemented, the divisor in this RowSample could be configurable. RFiles with sample data would store the fact that a RowSample with a divisor of 1009 was used to generate sample data.


--
This message was sent by Atlassian JIRA
(v6.3.4#6332)