I ran a query today to delete two rows that clocked in at just under two hours. A new personal record for time for rows deleted – one hour per row.

=> DELETE FROM metric WHERE name = 'networkin' OR name = 'networkout';
DELETE 2
Time: 6957592.469 ms (01:55:57.592)

metric is a tiny table itself, but it’s referenced by large partitioned tables for metric_point and metric_point_aggregate, both of which need to scanned in their entirety to verify that no rows reference either of these two being removed. Luckily, the operation didn’t need to hold a significant lock, and inserts and reads on all tables were healthy throughout.