After creating some captions on commons on beta I went to check the wb_terms table and it is indeed being used.
MariaDB [commonswiki]> select * from wb_terms; +-------------+----------------+---------------------+------------------+---------------+-----------+--------------------------------------+-----------------+-------------+ | term_row_id | term_entity_id | term_full_entity_id | term_entity_type | term_language | term_type | term_text | term_search_key | term_weight | +-------------+----------------+---------------------+------------------+---------------+-----------+--------------------------------------+-----------------+-------------+ | 1 | 0 | M59928 | mediainfo | en | label | Make a caption | | 0 | | 2 | 0 | M59928 | mediainfo | fr | label | Seulement une légende | | 0 | | 3 | 0 | M58796 | mediainfo | en | label | Procedurally generated crystal in 3D | | 0 | | 4 | 0 | M59928 | mediainfo | es | label | another caption | | 0 | +-------------+----------------+---------------------+------------------+---------------+-----------+--------------------------------------+-----------------+-------------+ 4 rows in set (0.00 sec)
Lexeme has been implemented without using this table.
Related is T198866 which lists the usecases within wikibase itself that we want to migrate away from.
Quote from IRC:
<duesen> Daniel Kinzler addshore: MediaInfo has no uniqueness constraints 5:10 PM we will want "label lookups" at some point
So it sounds like this might accidently be getting used right now while it is not needed?