The upgrade/downgrade process is only necessary for major or minor WiredTiger releases (releases where the major or minor version number changed). Patch releases (where only the patch number changed), do not contain any API or file format changes, and do not require anything other than a link step or shared library installation for upgrading or downgrading. However, the complete WiredTiger library must be re-built from scratch when changing versions, as there is no guarantee modules from one version of the library will work with modules from any other version.
The rest of this page discusses upgrading and downgrading WiredTiger major and minor releases. Specifically, by upgrading, we mean migrating an application and its databases to a newer WiredTiger release, and by downgrading, we mean reverting to an older version.
When upgrading or downgrading between WiredTiger releases, there are two components to consider: the WiredTiger library API and the underlying data files used for the database (for example, log files or B+tree files).
As part of each WiredTiger release, a new Upgrading WiredTiger applications documentation section is created, describing changes in the WiredTiger API and in the format of underlying files, if any. Changes to the format of the underlying data files are extremely rare, while changes to WiredTiger API are more common. Generally, when the WiredTiger API changes, the changes are backward compatible and applications do not require modifications in order to upgrade to the new release.
Note it is not necessary to upgrade (downgrade) to intermediate releases, you can ignore intermediate releases and upgrade (downgrade) directly to the release you plan to use.
To upgrade to a new release of WiredTiger:
Applications wanting the ability to downgrade to previous releases of WiredTiger are constrained in some important ways:
false, so WiredTiger does not write the base configuration file file when creating databases. Because the base configuration file is written using a current version of the WiredTiger API, writing this file could cause applications using previous versions of the WiredTiger API to fail. See WiredTiger.basecfg file for more information.
To downgrade to a previous release of WiredTiger: