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    <p>This sounds like a good use case for using one of Accumulo's SortedKeyValueIterators, specifically the FirstEntryInRowIterator (contained in the accumulo-core artifact).</p> <p>Create an IteratorSetting with the FirstEntryInRowIterator and add it to your BatchScanner. This will return the first Key/Value in that system_name, and then stop avoiding the overhead of your client ignoring all other results.</p> <p>A quick modification of the FirstEntryInRowIterator might get you what you want:</p> <pre><code>/* * 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.iterators; import java.io.IOException; import java.util.Collection; import java.util.HashMap; import java.util.Map; import org.apache.accumulo.core.client.IteratorSetting; import org.apache.accumulo.core.data.ByteSequence; import org.apache.accumulo.core.data.Key; import org.apache.accumulo.core.data.PartialKey; import org.apache.accumulo.core.data.Range; import org.apache.accumulo.core.data.Value; import org.apache.hadoop.io.Text; public class FirstEntryInRangeIterator extends SkippingIterator implements OptionDescriber { // options static final String NUM_SCANS_STRING_NAME = "scansBeforeSeek"; // iterator predecessor seek options to pass through private Range latestRange; private Collection&lt;ByteSequence&gt; latestColumnFamilies; private boolean latestInclusive; // private fields private Text lastRowFound; private int numscans; /** * convenience method to set the option to optimize the frequency of scans vs. seeks */ public static void setNumScansBeforeSeek(IteratorSetting cfg, int num) { cfg.addOption(NUM_SCANS_STRING_NAME, Integer.toString(num)); } // this must be public for OptionsDescriber public FirstEntryInRangeIterator() { super(); } public FirstEntryInRangeIterator(FirstEntryInRangeIterator other, IteratorEnvironment env) { super(); setSource(other.getSource().deepCopy(env)); } @Override public SortedKeyValueIterator&lt;Key,Value&gt; deepCopy(IteratorEnvironment env) { return new FirstEntryInRangeIterator(this, env); } @Override public void init(SortedKeyValueIterator&lt;Key,Value&gt; source, Map&lt;String,String&gt; options, IteratorEnvironment env) throws IOException { super.init(source, options, env); String o = options.get(NUM_SCANS_STRING_NAME); numscans = o == null ? 10 : Integer.parseInt(o); } // this is only ever called immediately after getting "next" entry @Override protected void consume() throws IOException { if (finished == true || lastRowFound == null) return; int count = 0; while (getSource().hasTop() &amp;&amp; lastRowFound.equals(getSource().getTopKey().getRow())) { // try to efficiently jump to the next matching key if (count &lt; numscans) { ++count; getSource().next(); // scan } else { // too many scans, just seek count = 0; // determine where to seek to, but don't go beyond the user-specified range Key nextKey = getSource().getTopKey().followingKey(PartialKey.ROW); if (!latestRange.afterEndKey(nextKey)) getSource().seek(new Range(nextKey, true, latestRange.getEndKey(), latestRange.isEndKeyInclusive()), latestColumnFamilies, latestInclusive); else { finished = true; break; } } } lastRowFound = getSource().hasTop() ? getSource().getTopKey().getRow(lastRowFound) : null; } private boolean finished = true; @Override public boolean hasTop() { return !finished &amp;&amp; getSource().hasTop(); } @Override public void seek(Range range, Collection&lt;ByteSequence&gt; columnFamilies, boolean inclusive) throws IOException { // save parameters for future internal seeks latestRange = range; latestColumnFamilies = columnFamilies; latestInclusive = inclusive; lastRowFound = null; super.seek(range, columnFamilies, inclusive); finished = false; if (getSource().hasTop()) { lastRowFound = getSource().getTopKey().getRow(); if (range.beforeStartKey(getSource().getTopKey())) consume(); } } @Override public IteratorOptions describeOptions() { String name = "firstEntry"; String desc = "Only allows iteration over the first entry per range"; HashMap&lt;String,String&gt; namedOptions = new HashMap&lt;String,String&gt;(); namedOptions.put(NUM_SCANS_STRING_NAME, "Number of scans to try before seeking [10]"); return new IteratorOptions(name, desc, namedOptions, null); } @Override public boolean validateOptions(Map&lt;String,String&gt; options) { try { String o = options.get(NUM_SCANS_STRING_NAME); if (o != null) Integer.parseInt(o); } catch (Exception e) { throw new IllegalArgumentException("bad integer " + NUM_SCANS_STRING_NAME + ":" + options.get(NUM_SCANS_STRING_NAME), e); } return true; } } </code></pre>
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    1. COIt looks like the original poster is creating a range per row. You don't even need to do that if you use the FirstEntryInRowIterator. Batch scanning may still be useful, but not to achieve this particular functionality.
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    2. COThanks for the reply elserj. I started playing with this a little but haven't been able to get what I want. I want to dig into a little more. See my edit for a description of what I am seeing currently.
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    3. COAh, so the FirstEntryInRowIterator attempts to find you the first Key/Value in the row from the startKey in the Range you provide (in your example, it changes the startKey of the Range you provided from "row fam:qual2" to just "row"). So, the iterator attempts to return you the Key "rom fam:qual1", which happens to fall outside of the Range you provided, and thus you get no results.
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