Metadata

This type contains information about the versions this index works currently with.

This type only contains one document and is actually never searched, but directly accessed as “metadata/1”.

Easydb uses this information to detect an obsolete mapping that needs to be updated. The index_version and base_schema_version can only change when updating the Easydb software. The user_schema_version changes every time a user commits a new schema and maskset version.

If the Easydb notices a change in the base_schema_version or the index_version, it will destroy the current index and build a new one, as there may be changes in the mappings that are incompatible with the code. But in the case of a change of the index_version, only the mappings will be updated. As the objects are reindexed, which may take a long time, the older versions are replaced with the new ones.

The attribute _schema_version contains the object’s current user schema version. At a certain moment, there may be objects with different _schema_version numbers. The document “metadata/1” contains the current user_schema_version, so that a client can know whether the result of a search is the current object or an older version.