TABLESAMPLE SYSTEM (0.5) read 30 s of random pages on the HDD at 7M
releases, growing with the catalog; a refresh that never finished kept
the header's totals 3.5 hours old (it blocked every later refresh).
Now TABLESAMPLE SYSTEM_ROWS (5000) (tsm_system_rows), every 5 minutes,
and a refresh is given up after 2 minutes.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
