Remnant entities (or ghosts) are assignments in tables without a corresponding entry in a the
smw_proptable_hash field of database table
smw object ids.
smw_proptable_hash field for an entity contains the collective hash of those values that the tables (hereby annotations) currently suppose to have assignments for to provide an efficient diffing mechanism for the updater to decided which tables require an insert/delete without reading each single table and compare its values.
The occurrence of remnant entities should rarely happen but has been observed 1 and is most likely caused by an aborted update with an unsuccessful rollback which under some circumstances can create an imbalance in the record of the
$smwgCheckForRemnantEntitiesNo description was provided.2 is provided to help remove entities classified as remnant by running additional table queries during an update. This may have a performance impact therefore see the configuration parameters documentation for further information.
- Help page on outdated entities
- Help page on Configuration parameter
$smwgCheckForRemnantEntitiesNo description was provided.
- ^ Semantic MediaWiki: GitHub issue gh:smw:3849
- ^ Semantic MediaWiki: GitHub pull request gh:smw:3866