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From kot...@apache.org
Subject svn commit: r1825865 - /subversion/site/staging/docs/release-notes/1.10.html
Date Mon, 05 Mar 2018 10:45:59 GMT
Author: kotkov
Date: Mon Mar  5 10:45:59 2018
New Revision: 1825865

URL: http://svn.apache.org/viewvc?rev=1825865&view=rev
Log:
Extend the 1.10 release notes with a subsection about using LZ4 compression
over the wire.  For now, only document the negotiation and choice of the
compression algorithm for http://, and leave a TODO about svn://.

* docs/release-notes/1.10.html
  (LZ4 compression): Extend the opener with the information that LZ4
   compression is supported for both http:// and svn://.
  (LZ4 compression over the wire in http:// and svn:// connections):
   New subsection.
  (New Feature Compatibility Table): Link to the new subsection.

Modified:
    subversion/site/staging/docs/release-notes/1.10.html

Modified: subversion/site/staging/docs/release-notes/1.10.html
URL: http://svn.apache.org/viewvc/subversion/site/staging/docs/release-notes/1.10.html?rev=1825865&r1=1825864&r2=1825865&view=diff
==============================================================================
--- subversion/site/staging/docs/release-notes/1.10.html (original)
+++ subversion/site/staging/docs/release-notes/1.10.html Mon Mar  5 10:45:59 2018
@@ -136,7 +136,7 @@ and what impact these changes may have.<
     <td>Use SVN 1.8 and above clients only for best results.</td></tr>
   <tr>
     <td>
-      <a href="#lz4">LZ4 compression over the wire in http:// connections</a>
+      <a href="#lz4-over-the-wire">LZ4 compression over the wire in http:// and svn://
connections</a>
     </td>
     <td>1.10</td>
     <td>1.10</td>
@@ -542,7 +542,9 @@ containing large files.
 </p>
 
 <p>LZ4 compression is now used by default for the on-disk data in repositories
-with filesystem format 8 (see below).</p>
+with filesystem format 8.  Also, Subversion 1.10 adds support for automatic
+negotiation and use of LZ4 compression over the wire for http:// and svn://
+connections when it is supported by both endpoints.</p>
 
 <p><b>Note:</b> this does not apply to the pre-release
 <a href="https://lists.apache.org/thread.html/dd78432b301f3f95567930c242c46b308c8a017fd754c0f388245915@%3Cannounce.subversion.apache.org%3E">Subversion
1.10.0-alpha3</a>
@@ -602,6 +604,119 @@ cycle into a new format 8 repository cre
 
 </div>  <!-- fsfs-lz4-configuration -->
 
+<div class="h4" id="lz4-over-the-wire">
+<h4>LZ4 compression over the wire in http:// and svn:// connections
+  <a class="sectionlink" href="#lz4-over-the-wire"
+     title="Link to this section">&para;</a>
+</h4>
+
+<p>Deltas transferred between Subversion 1.10 clients and servers may be
+compressed with LZ4.  The actual choice of the compression algorithm depends
+on the used protocol, environment and its configuration &mdash; see below.</p>
+
+<p>For <b>http://</b> protocol, use of LZ4 compression depends on the values
+of the server-side <tt>SVNCompressionLevel</tt> directive, client-side
+<tt>http-compression</tt> configuration option and on the network
+capabilities.  LZ4 compression generally offers much faster compression
+and decompression speeds, but slightly worse compression ratio than zlib.
+By default, it is only preferred for low latency networks where the
+overhead associated with transferring the additional amount of data is
+assumed to be negligible.<p>
+
+<ul>
+  <li>
+    <p>On the <b>server-side</b>, <tt>SVNCompressionLevel 0</tt>
+    can be used to disable compression altogether.  The special value of
+    <tt>SVNCompressionLevel 1</tt> forces the use of LZ4 compression for
+    clients that support it. All other values result in preferring zlib
+    compression with the respective compression level.  Note that the
+    negotiated algorithm is still subject to the client's configuration.
+    For example, even if the server is configured to prefer zlib compression
+    over LZ4, a client may still negotiate the use of LZ4 compression when
+    its <tt>http-compression</tt> option is set to <tt>auto</tt>.</p>
+  </li>
+  <li>
+    <p>On the <b>client-side</b>, setting <tt>http-compression</tt>
to
+    either <tt>yes</tt> or <tt>no</tt> will enable or disable compression
+    that is then negotiated based on the server's configuration.
+    The default value of <tt>auto</tt> will result in preferring LZ4
+    compression for low latency networks and zlib compression otherwise.</p>
+  </li>
+</ul>
+
+<p>Below is the table explaining the used compression algorithm in each
+combination of the client- and server-side configuration options:</p>
+
+<table border="1">
+  <tr>
+    <th></th>
+    <th colspan="3">1.10 Server<br />with SVNCompressionLevel:</th>
+    <th colspan="2">1.9 and older Server<br />with SVNCompressionLevel:</th>
+  </tr>
+  <tr>
+    <th>Subversion Client</th>
+    <th>0</th>
+    <th>1</th>
+    <th>2-9 (default:&nbsp;5)<sup>*</sup></th>
+    <th>0</th>
+    <th>1-9 (default:&nbsp;5)<sup>*</sup></th>
+  </tr>
+  <tr>
+    <td>1.10, <tt>http-compression: auto</tt><sup>*</sup>,
low latency</td>
+    <td>No compression</td>
+    <td><b>LZ4</b> compression</td>
+    <td><b>LZ4</b> compression</td>
+    <td>No compression</td>
+    <td>zlib compression</td>
+  </tr>
+  <tr>
+    <td>1.10, <tt>http-compression: auto</tt><sup>*</sup>,
high latency</td>
+    <td>No compression</td>
+    <td><b>LZ4</b> compression</td>
+    <td>zlib compression</td>
+    <td>No compression</td>
+    <td>zlib compression</td>
+  </tr>
+  <tr>
+    <td>1.10, <tt>http-compression: yes</tt></td>
+    <td>No compression</td>
+    <td><b>LZ4</b> compression</td>
+    <td>zlib compression</td>
+    <td>No compression</td>
+    <td>zlib compression</td>
+  </tr>
+  <tr>
+    <td>1.10, <tt>http-compression: no</tt></td>
+    <td>No compression</td>
+    <td>No compression</td>
+    <td>No compression</td>
+    <td>No compression</td>
+    <td>No compression</td>
+  </tr>
+  <tr>
+    <td>1.9 and older, <tt>http-compression: yes</tt><sup>*</sup></td>
+    <td>No compression</td>
+    <td>zlib compression</td>
+    <td>zlib compression</td>
+    <td>No compression</td>
+    <td>zlib compression</td>
+  </tr>
+  <tr>
+    <td>1.9 and older, <tt>http-compression: no</tt></td>
+    <td>No compression</td>
+    <td>No compression</td>
+    <td>No compression</td>
+    <td>No compression</td>
+    <td>No compression</td>
+  </tr>
+</table>
+
+<p><sup>*</sup>&nbsp;Default configurations</p>
+
+<!-- TODO: describe LZ4 over svn:// -->
+
+</div>  <!-- lz4-over-the-wire -->
+
 </div>  <!-- lz4 -->
 
 <div class="h3" id="shelving">



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