How to limit number of concurrent very large grouping yearly mergeouts
Happy New Year!
And, this is the time of the year when Vertica is doing grouping for yearly partitions.
I found that in one of my smallish Vertica clusters I have a bunch of aborted mergeouts, due to running out of temp disk space.
Investigation shows, there are two largest tables roughly same size, and they undergo merging of 2021 data into single yearly partition grouping.
There is enough temp space, and it is on same large disk as data.
Problem here is that Vertica starts at least 3 very large grouping yearly mergeout in parallel on each node.
While it is enough disk space for single yearly mergeout, database cannot fit temp space for 3 yearly mergeouts running in parallel.
I can limit max size of merged ROS, and yearly mergeouts will go through, resulting into several ROS per year. That would work but would be undesired outcome.
Apart from this very large yearly mergeouts, tuple mover works perfectly well, never had problems on this cluster.
Database easily fit several monthly mergeouts concurrently on each node.
Question: How to limit number and total size of concurrent mergeouts per node for very large mergeouts on data that is outside of active partitions?
(I can suggest MaxTotalMergeoutSize, total size of mergeouts per node cannot go above that)