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A GConf backend is an adaptor to permit GConf to store configuration
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information in some form of 'database'. The XML backend uses files
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and a file-system directory structure to store key-value pairs,
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schemas, and to represent the key hierarchy. The Berkeley DB
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backend uses Sleepycat's distribution of the Berkeley DB
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database toolkit to provide a relatively high performance GConf
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If you decide not to build the Berkeley DB backend, simply remove
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the reference to libgconfbackend-bdb.la in the definition of
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backend_LTLIBRARIES in backends/Makefile.
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See comments in bdb.h for an description of the databases and
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Notes for this initial release:
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- there are bound to be bugs, but the backend passes the GConf
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test suite (extended to include some schema-usage tests)
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- some concurrency control has been built-in, but this has not
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been adequately tested
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- by design there is no cache so that concurrent writers may
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be supported, but despite this performance is good and the
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testpersistence test (which synchronises each change individually
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to the GConfd database) is noticably faster than with the XML backend.
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- Previous versions of Berkeley DB have altered the database structure in
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ways that are not backward compatible. If this occurs with future versions
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of Berkeley DB (after version 3.1.17), the major version number of the
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backend shared library will be incremented.
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- The backend uses a relatively new feature of Berkeley DB, the support
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for duplicate keys in a single database table. Currently Berkeley DB
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produces warning messages 'Duplicate data items are not supported with
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sorted data'. Sleepycat have said that this message is only to warn
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developers while the duplicate-support feature is new and will be removed
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- There is also an error that occasionally "corrupts" the key-hierarchy
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database which prevents the directory hierarchy from being traversed.
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Currently it is not clear if this is an error in the backend or in
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the database toolkit. This error can be seen in the testdirlist test
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program which initially works but after running all tests a few
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times, testdirlist produces an error message "*** FAILED: Did not get
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'testing' in listing of / after setting keys such as /testing/foo/bar/woo".
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This bug is under investigation, as it prevents serious use of
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the Berkeley DB backend, although applications which do not use the
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gconf_all_dirs() API should not encounter this problem.
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You can obtain the source distribution for Berkeley DB from Sleepycat
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Software at http://www.sleepycat.com/download.html. The current
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Colm Smyth (colm.smyth@sun.com)
added
removed
backends/README.bdb
