Details of dev-db/mongodb:

To upgrade from a version earlier than the 3.4-series, you must
successively upgrade major releases until you have upgraded
to 3.4-series. Then upgrade to 3.6 series.
Be sure to set featureCompatibilityVersion to 3.4 before upgrading.
Make sure to read the release notes and follow the upgrade process:
  https://docs.mongodb.com/manual/release-notes/$(get_version_component_range 1-2)/
  https://docs.mongodb.com/manual/release-notes/$(get_version_component_range 1-2)/#upgrade-procedures

To upgrade from a version earlier than the 3.4-series, you must
successively upgrade major releases until you have upgraded
to 3.4-series. Then upgrade to 3.6 series.
Be sure to set featureCompatibilityVersion to 3.4 before upgrading.
Make sure to read the release notes and follow the upgrade process:
  https://docs.mongodb.com/manual/release-notes/$(get_version_component_range 1-2)/
  https://docs.mongodb.com/manual/release-notes/$(get_version_component_range 1-2)/#upgrade-procedures

To upgrade from a version earlier than the 3.4-series, you must
successively upgrade major releases until you have upgraded
to 3.4-series. Then upgrade to 3.6 series.
Be sure to set featureCompatibilityVersion to 3.4 before upgrading.
Make sure to read the release notes and follow the upgrade process:
  https://docs.mongodb.com/manual/release-notes/$(get_version_component_range 1-2)/
  https://docs.mongodb.com/manual/release-notes/$(get_version_component_range 1-2)/#upgrade-procedures

To upgrade from a version earlier than the 3.4-series, you must
successively upgrade major releases until you have upgraded
to 3.4-series. Then upgrade to 3.6 series.
Be sure to set featureCompatibilityVersion to 3.4 before upgrading.
Make sure to read the release notes and follow the upgrade process:
  https://docs.mongodb.com/manual/release-notes/$(get_version_component_range 1-2)/
  https://docs.mongodb.com/manual/release-notes/$(get_version_component_range 1-2)/#upgrade-procedures

To upgrade from a version earlier than the 3.2-series, you must
successively upgrade major releases until you have upgraded
to 3.2-series. Then upgrade to 3.4 series.
Make sure to read the release notes and follow the upgrade process:
  https://docs.mongodb.com/manual/release-notes/$(get_version_component_range 1-2)/
  https://docs.mongodb.com/manual/release-notes/$(get_version_component_range 1-2)/#upgrade-procedures

To upgrade from a version earlier than the 3.2-series, you must
successively upgrade major releases until you have upgraded
to 3.2-series. Then upgrade to 3.4 series.
Make sure to read the release notes and follow the upgrade process:
  https://docs.mongodb.com/manual/release-notes/$(get_version_component_range 1-2)/
  https://docs.mongodb.com/manual/release-notes/$(get_version_component_range 1-2)/#upgrade-procedures

To upgrade from a version earlier than the 3.2-series, you must
successively upgrade major releases until you have upgraded
to 3.2-series. Then upgrade to 3.4 series.
Make sure to read the release notes and follow the upgrade process:
  https://docs.mongodb.com/manual/release-notes/$(get_version_component_range 1-2)/
  https://docs.mongodb.com/manual/release-notes/$(get_version_component_range 1-2)/#upgrade-procedures

To upgrade from a version earlier than the 3.0-series, you must
successively upgrade major releases until you have upgraded
to 3.2-series. Then upgrade to 3.4 series.
!! IMPORTANT !!
 
${PN} configuration files have changed !
 
Make sure you migrate from /etc/conf.d/${PN} to the new YAML standard in /etc/${PN}.conf
  http://docs.mongodb.org/manual/reference/configuration-options/
 
Make sure you also follow the upgrading process :
  http://docs.mongodb.org/master/release-notes/3.0-upgrade/
 
MongoDB 3.0 introduces the WiredTiger storage engine.
WiredTiger is incompatible with MMAPv1 and you need to dump/reload your data if you want to use it.
Once you have your data dumped, you need to set storage.engine: wiredTiger in /etc/${PN}.conf
  http://docs.mongodb.org/master/release-notes/3.0-upgrade/#change-storage-engine-to-wiredtiger
Make sure to read the release notes and follow the upgrade process:
  https://docs.mongodb.org/manual/release-notes/3.4/
  https://docs.mongodb.com/manual/release-notes/3.4/#upgrade-procedures

To upgrade an existing MongoDB deployment to 3.2, you must be
running a 3.0-series release. Please update to the latest 3.0
release before continuing if wish to keep your data.
!! IMPORTANT !!
 
${PN} configuration files have changed !
 
Make sure you migrate from /etc/conf.d/${PN} to the new YAML standard in /etc/${PN}.conf
  http://docs.mongodb.org/manual/reference/configuration-options/
 
Make sure you also follow the upgrading process :
  http://docs.mongodb.org/master/release-notes/3.0-upgrade/
 
MongoDB 3.0 introduces the WiredTiger storage engine.
WiredTiger is incompatible with MMAPv1 and you need to dump/reload your data if you want to use it.
Once you have your data dumped, you need to set storage.engine: wiredTiger in /etc/${PN}.conf
  http://docs.mongodb.org/master/release-notes/3.0-upgrade/#change-storage-engine-to-wiredtiger
Make sure to read the release notes and follow the upgrade process:
  https://docs.mongodb.org/manual/release-notes/3.2/
  https://docs.mongodb.org/master/release-notes/3.2-upgrade/
 Starting in 3.2, MongoDB uses the WiredTiger as the default storage engine.

!! IMPORTANT !!
 
${PN} configuration files have changed !
 
Make sure you migrate from /etc/conf.d/${PN} to the new YAML standard in /etc/${PN}.conf
  http://docs.mongodb.org/manual/reference/configuration-options/
 
Make sure you also follow the upgrading process :
  http://docs.mongodb.org/master/release-notes/3.0-upgrade/
 
MongoDB 3.0 introduces the WiredTiger storage engine.
WiredTiger is incompatible with MMAPv1 and you need to dump/reload your data if you want to use it.
Once you have your data dumped, you need to set storage.engine: wiredTiger in /etc/${PN}.conf
  http://docs.mongodb.org/master/release-notes/3.0-upgrade/#change-storage-engine-to-wiredtiger

!! IMPORTANT !!
 
${PN} configuration files have changed !
 
Make sure you migrate from /etc/conf.d/${PN} to the new YAML standard in /etc/${PN}.conf
  http://docs.mongodb.org/manual/reference/configuration-options/
 
Make sure you also follow the upgrading process :
  http://docs.mongodb.org/master/release-notes/3.0-upgrade/
 
MongoDB 3.0 introduces the WiredTiger storage engine.
WiredTiger is incompatible with MMAPv1 and you need to dump/reload your data if you want to use it.
Once you have your data dumped, you need to set storage.engine: wiredTiger in /etc/${PN}.conf
  http://docs.mongodb.org/master/release-notes/3.0-upgrade/#change-storage-engine-to-wiredtiger