I had cause to change some data in a data model today, which made some fields redundant. I dropped the table cache, rescanned and did all that good stuff and everything seemed fine.
When I x-ray’ed the table I noticed some blank / erroneous cards were being shown, and upon further investigation, these related to a date object which had been removed - the grouping retained a ::month suffix but the object was no longer present, hence the error.
Checking the internal database, I noted there remains entries for the fields which had been rendered obselete in the metabase_fields table, & they were all marked as active=false; I’m guessing the x-ray operation didn’t pick this up for some reason? I hadn’t restarted so it could be a cache issue; I’m not losing any sleep over it.
I removed these entries directly via SQL, and also their associated entries in the metabase_fieldvalues table, and the x-ray seemed to work again. Everything seems to be working so I’m assuming i haven’t boned anything important - just leaving this here for posterity in case anyone else runs up against the same issue.
Edit: I should add, 0.29.3, and I checked for any dependencies before I got all trigger happy with the delete statements.