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sks-keyserver-with-async / UPGRADING

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In general, it is possible to upgrade a database to a new version of
Berkeley DB without rebuilding as most upgrades of bdb only require a
change to the log file.

For example, if one wishes to upgrade sks and bdb from db51 to db53:

  <shutdown SKS linked with libdb5.1, backup DB dirs>
  cd /var/sks                # default location
  for DB in KDB PTree
  do
    db51_recover    -eh $DB  # feels extra, some Oracle docs recommend
    db51_recover     -h $DB  # run again, this time removing DB env
    db51_checkpoint -1h $DB  # checkpoint with old version
  done
  #
  <At this point, either upgrade bdb & libdb to the new version
   or install them if they are setup for multiple versions to coexist>
  #
  for DB in KDB PTree
  do
    db53_checkpoint -1h $DB  # checkpoint and convert the log
    db53_recover    -eh $DB  # run db_recover and recreate env
    db53_archive    -dh $DB  # remove old log files
  done
  #
  <Install new SKS release from distro or cd to SKS src dir and
   'make install' the SKS version linked with libdb5.3>
  <restart SKS>

see http://docs.oracle.com/cd/E17275_01/html/programmer_reference/upgrade_process.html
as well as the release notes for the new version of bdb being installed

Help is, as usual, available from the Sks-devel mailing list,
Sks-devel@nongnu.org. https://lists.nongnu.org/mailman/listinfo/sks-devel