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From keith-turner <...@git.apache.org>
Subject [GitHub] accumulo pull request #180: Taking a crack at new summarization API
Date Thu, 10 Nov 2016 20:28:14 GMT
Github user keith-turner commented on a diff in the pull request:

    https://github.com/apache/accumulo/pull/180#discussion_r87478881
  
    --- Diff: core/src/main/java/org/apache/accumulo/core/client/admin/SummaryRetriever.java
---
    @@ -0,0 +1,46 @@
    +/*
    + * 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.admin;
    +
    +import java.util.Map;
    +
    +import org.apache.hadoop.io.Text;
    +
    +public interface SummaryRetriever {
    +
    +  /**
    +   * Allows optionally setting start row before retrieving data.
    +   */
    +  SummaryRetriever start(Text startRow);
    --- End diff --
    
    I was also thinking that multiple summaries could be kept per rfile. That could work something
like the following.
    
     * After 1,000 key values are written create a Tuple\<end row, summary\>
     * Add this tuple to an in memory list of the form List\<Tuble\<endrow, summary\>>
called summaryList.  
     * If summaryList exceeds 10, then merge as merge(summaryList[0],  summaryList[1]),  merge(summaryList[2],
 summaryList[3]), etc... halving the size of the list.
    
    So basically we could easily build more granular summary info within a file that, does
not exceed a fixed size, by leveraging the merge functionality of a summarizer.


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