[mapserver-users] Mapcache: error with Berkeley DB and display tiles

[Eichner, Andreas - SID-NLKM]

> Andreas, thanks for the explanation about the Berkeley Database.
> However, I have made several changes of permissions and owner of the
> files produced by mapcache_seed, and I still get the same error on
> the OpenLayers demo.
> 
> I don't know if others users have had the same error with Mapcache
> and Berkeley Databases in Ubuntu Server.
> 

Have you build mapcache yourself or do you use a prebuild one? Today I build mapcache with BerkeleyDB support on a Debian Testing box. Basically, this is what I did:

* check out latest master
* apt-get install libdb5.1-dev
* follow the install instructions in INSTALL, add -DWITH_BERKELEY_DB=ON to "cmake .." and make sure "* Berkeley DB: /usr/lib/..." is listed under "Optional components"
* add the following config element to mapcache.xml if it does not exist yet:
   <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>
* create the base directory and grant access to web server:
  # mkdir /tmp/foo && chgrp www-data /tmp/foo && chmod g+rwx /tmp/foo
* set the <cache> element to "bdb" in a tileset
* populate the cache by seeding a tileset that uses a bdb-cache
* the base should look something like this:
# ls -l /tmp/foo/
insgesamt 11528
-rw-r--r-- 1 www-data www-data 9764864 Jan 28 13:30 bdb.db
-rw-r----- 1 www-data www-data   24576 Jan 28 13:35 __db.001
-rw-r----- 1 www-data www-data  253952 Jan 28 13:35 __db.002
-rw-r----- 1 www-data www-data 1318912 Jan 28 13:35 __db.003
-rw-r----- 1 www-data www-data  811008 Jan 28 13:35 __db.004

* to verify this worked use the strings command on the bdb.db and grep for the tileset name: # strings /tmp/foo/bdb.db|grep MyTilesetName
* use the demo service to check if it is working