I have a cluster with a constant trickle load of new data fed by a stream of large batch COPY statements and also simultaneously support interactive read-queries against the most recently added data, i.e. time series for chart data.
How can I control the Tuple Mover so that it spreads out its work over a longer period of time, to reduce the insane disk I/O it periodically causes which slows down read-query performance to horrible levels. This data is partitioned on a date column, so every 24 hours precisely (GMT) there is a flurry of disk I/O due to partition mini-ROS to ROS consolidation. I've set ActivePartitions to 2, long ago, which helped reduce the problem but it's still a significant slowdown while the mergout is hogging the spindles.
It seems like the resource pool settings ought to help, but I can't find a setting that has an effect. Any suggestions?