Eleven indexes that existed only for reporting

Indexes on production tables serving queries that no user request ever makes.

SELECT s.table_name, s.index_name
FROM information_schema.statistics s
LEFT JOIN performance_schema.table_io_waits_summary_by_index_usage u
  ON u.object_name = s.table_name AND u.index_name = s.index_name
WHERE s.table_schema = DATABASE()
GROUP BY 1, 2
HAVING COALESCE(MAX(u.count_read), 0) < 1000;

-- cross-referenced against the reporting query log:
-- 11 of 14 are read only by reports.

An index that serves only reporting is paying a write cost on every insert to make a query fast that runs eleven times a month, which is a trade nobody makes deliberately and everybody makes incrementally. Moving the reports to their own database is what makes dropping them possible.