sys.dm_tran_top_version_generators reads the whole version store. It ran
every 5 minutes while the version store was over half the threshold,
i.e. exactly when it is large and expensive to scan, and a timeout failed
the whole tempdb collection. It now runs at most once per hour (the
previous answer is kept in between, with its time) and a failed scan
keeps the previous answer.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>