Author: buildbot
Date: Fri Apr 4 21:08:52 2014
New Revision: 904956
Log:
Staging update by buildbot for accumulo
Modified:
websites/staging/accumulo/trunk/content/ (props changed)
websites/staging/accumulo/trunk/content/release_notes/1.6.0.html
Propchange: websites/staging/accumulo/trunk/content/
------------------------------------------------------------------------------
--- cms:source-revision (original)
+++ cms:source-revision Fri Apr 4 21:08:52 2014
@@ -1 +1 @@
-1584908
+1584912
Modified: websites/staging/accumulo/trunk/content/release_notes/1.6.0.html
==============================================================================
--- websites/staging/accumulo/trunk/content/release_notes/1.6.0.html (original)
+++ websites/staging/accumulo/trunk/content/release_notes/1.6.0.html Fri Apr 4
21:08:52 2014
@@ -114,15 +114,17 @@
<p>One of the key elements of the Big Table design is use of the Log
Structured Merge Tree (LSMT) concept. This entails sorting data in memory,
writing out sorted files, and then later merging multiple sorted files into a
single file. These automatic merges happen in the background and Accumulo
decides when to merge files based comparing relative sizes of files to a
compaction ratio. Adjusting the compaction ratio is the only way a user can
control this process. <a
href="https://issues.apache.org/jira/browse/ACCUMULO-1451"; title="Make
Compaction triggers extensible">ACCUMULO-1451</a> introduces pluggable
compaction strategies which allow users to choose when and what files to
compact. <a href="https://issues.apache.org/jira/browse/ACCUMULO-1808";
title="Create compaction strategy that has size limit">ACCUMULO-1808</a> adds a
compaction strategy the prevents compaction of files over a configurable
size.</p>
<h3 id="lexicoders">Lexicoders</h3>
<p>Accumulo only sorts data lexicographically. Getting something like a pair
of (<string>,<integer>) to sort correctly in Accumulo is tricky. Its tricky
because you only want to compare the integers if the strings are equal. Its
possible to make this sort properly in Accumulo if the data is encoded
properly, but that's the tricky part. To make this easier <a
href="https://issues.apache.org/jira/browse/ACCUMULO-1336"; title="Add
lexicoders from Typo to Accumulo">ACCUMULO-1336</a> added Lexicoders to the
Accumulo API. Lexicoders provide an easy way to serialize data so that it
sorts properly lexicographically. Below is a simple example.</p>
-<blockquote>
-<p>PairLexicoder plex = new PairLexicoder(new StringLexicoder(), new
IntegerLexicoder());
-byte[] ba1 = plex.encode(new ComparablePair<String, Integer>("b",1));
-byte[] ba2 = plex.encode(new ComparablePair<String, Integer>("aa",1));
-byte[] ba3 = plex.encode(new ComparablePair<String, Integer>("a",2));
-byte[] ba4 = plex.encode(new ComparablePair<String, Integer>("a",1));
-byte[] ba5 = plex.encode(new ComparablePair<String, Integer>("aa",-3));</p>
-<p>//sorting ba1,ba2,ba3,ba4, and ba5 lexicographically will result in the
same order as sorting the ComparablePairs</p>
-</blockquote>
+<div class="codehilite"><pre> <span class="n">PairLexicoder</span> <span
class="n">plex</span> <span class="p">=</span> <span class="n">new</span> <span
class="n">PairLexicoder</span><span class="p">(</span><span
class="n">new</span> <span class="n">StringLexicoder</span><span
class="p">(),</span> <span class="n">new</span> <span
class="n">IntegerLexicoder</span><span class="p">());</span>
+ <span class="n">byte</span><span class="p">[]</span> <span
class="n">ba1</span> <span class="p">=</span> <span class="n">plex</span><span
class="p">.</span><span class="n">encode</span><span class="p">(</span><span
class="n">new</span> <span class="n">ComparablePair</span><span
class="o"><</span><span class="n">String</span><span class="p">,</span>
<span class="n">Integer</span><span class="o">></span><span
class="p">(</span>"<span class="n">b</span>"<span
class="p">,</span>1<span class="p">));</span>
+ <span class="n">byte</span><span class="p">[]</span> <span
class="n">ba2</span> <span class="p">=</span> <span class="n">plex</span><span
class="p">.</span><span class="n">encode</span><span class="p">(</span><span
class="n">new</span> <span class="n">ComparablePair</span><span
class="o"><</span><span class="n">String</span><span class="p">,</span>
<span class="n">Integer</span><span class="o">></span><span
class="p">(</span>"<span class="n">aa</span>"<span
class="p">,</span>1<span class="p">));</span>
+ <span class="n">byte</span><span class="p">[]</span> <span
class="n">ba3</span> <span class="p">=</span> <span class="n">plex</span><span
class="p">.</span><span class="n">encode</span><span class="p">(</span><span
class="n">new</span> <span class="n">ComparablePair</span><span
class="o"><</span><span class="n">String</span><span class="p">,</span>
<span class="n">Integer</span><span class="o">></span><span
class="p">(</span>"<span class="n">a</span>"<span
class="p">,</span>2<span class="p">));</span>
+ <span class="n">byte</span><span class="p">[]</span> <span
class="n">ba4</span> <span class="p">=</span> <span class="n">plex</span><span
class="p">.</span><span class="n">encode</span><span class="p">(</span><span
class="n">new</span> <span class="n">ComparablePair</span><span
class="o"><</span><span class="n">String</span><span class="p">,</span>
<span class="n">Integer</span><span class="o">></span><span
class="p">(</span>"<span class="n">a</span>"<span
class="p">,</span>1<span class="p">));</span>
+ <span class="n">byte</span><span class="p">[]</span> <span
class="n">ba5</span> <span class="p">=</span> <span class="n">plex</span><span
class="p">.</span><span class="n">encode</span><span class="p">(</span><span
class="n">new</span> <span class="n">ComparablePair</span><span
class="o"><</span><span class="n">String</span><span class="p">,</span>
<span class="n">Integer</span><span class="o">></span><span
class="p">(</span>"<span class="n">aa</span>"<span
class="p">,</span><span class="o">-</span>3<span class="p">));</span>
+
+ <span class="o">//</span><span class="n">sorting</span> <span
class="n">ba1</span><span class="p">,</span><span class="n">ba2</span><span
class="p">,</span><span class="n">ba3</span><span class="p">,</span><span
class="n">ba4</span><span class="p">,</span> <span class="n">and</span> <span
class="n">ba5</span> <span class="n">lexicographically</span> <span
class="n">will</span> <span class="n">result</span> <span class="n">in</span>
<span class="n">the</span> <span class="n">same</span> <span
class="n">order</span> <span class="n">as</span> <span class="n">sorting</span>
<span class="n">the</span> <span class="n">ComparablePairs</span>
+</pre></div>
+
+
<h3 id="multi-table-accumulo-input-format">Multi-table Accumulo input
format</h3>
<p><a href="https://issues.apache.org/jira/browse/ACCUMULO-391";
title="Multi-table input format">ACCUMULO-391</a> makes it possible to easily
read from multiple tables in a Map Reduce job. TODO is there more to say about
this, if not maybe move to one-liners.</p>
<h3 id="locality-groups-in-memory">Locality groups in memory</h3>
