[mapserver-commits] r13270 - trunk/docs/en/mapcache

[svn at osgeo.org]

Author: tbonfort
Date: 2012-03-16 06:03:53 -0700 (Fri, 16 Mar 2012)
New Revision: 13270

Modified:
   trunk/docs/en/mapcache/caches.txt
   trunk/docs/en/mapcache/index.txt
Log:
add docs for berkeleyDB cache backend


Modified: trunk/docs/en/mapcache/caches.txt
===================================================================
--- trunk/docs/en/mapcache/caches.txt	2012-03-16 12:47:48 UTC (rev 13269)
+++ trunk/docs/en/mapcache/caches.txt	2012-03-16 13:03:53 UTC (rev 13270)
@@ -88,6 +88,46 @@
       <template>/tmp/template-test/{tileset}#{grid}#{dim}/{z}/{x}/{y}.{ext}</template>
    </cache>
 
+
+.. _mapcache_cache_bdb:
+
+BerkeleyDB Caches
+--------------------------------------------------------------------------------
+
+The BerkeleyDB cache backend stores tiles in a key-value flat-file database.
+and therefore does not have the disadvantages of disk caches with regards to
+the number of files stored on the filesystem. As the image blobs are stored
+contiguously, the block size chosen for the filesystem has no influence on the
+storage capacity of the volume.
+
+Note that for a given bdb cache, only a single database file is created, which
+will store the tiles of its associated tilesets (i.e. there is not a database
+file created per tileset, grid, and or dimension). If you need to store different
+tilesets to different files, then use multiple dbd cache entries. It is not
+possible to use multiple database files for tileset grids or dimensions.
+
+The berkeleyDB based caches are a bit faster than the disk based caches during
+reads, but may be a bit slower during concurrent writes if a high number of
+threads all try to insert new tiles concurrently.
+
+.. code-block:: xml
+
+   <cache name="bdb" type="bdb">
+      <!-- base (required)
+         absolute filesystem path where the berkeley db database file is to be stored.
+         this directory must exist, and be writable
+      -->
+      <base>/tmp/foo/</base>
+      
+      <!-- key_template (optional)
+         string template used to create the key for a tile entry in the database.
+         defaults to the value below. you should include {tileset}, {grid} and {dim} here
+         unless you know what you are doing, or you will end up with mixed tiles
+      <key_template>{tileset}-{grid}-{dim}-{z}-{y}-{x}.{ext}</key_template>
+      -->
+   </cache>
+
+
 .. _mapcache_cache_sqlite:
 
 Sqlite Caches

Modified: trunk/docs/en/mapcache/index.txt
===================================================================
--- trunk/docs/en/mapcache/index.txt	2012-03-16 12:47:48 UTC (rev 13269)
+++ trunk/docs/en/mapcache/index.txt	2012-03-16 13:03:53 UTC (rev 13270)
@@ -44,6 +44,7 @@
 * cache types:
   
   * :ref:`Disk <mapcache_cache_disk>`
+  * :ref:`BerkeleyDB <mapcache_cache_bdb>`
   * :ref:`Sqlite <mapcache_cache_sqlite>`
   * :ref:`Memcached <mapcache_cache_memcache>`
   * :ref:`Tiled TIFFs <mapcache_cache_tiff>`