I was going through an article
Scaling CrateDB clusters up and down to cope with peaks in demand - Tutorials - CrateDB Community
in this below notes,
When we are ready to decommission the temporary nodes, we need to move the data collected during the days of the event.
In CrateDB 5.1.2 or higher we can achieve this with:
ALTER TABLE test SET ("routing.allocation.exclude.storage" = 'temporarynodes');
ALTER TABLE test RESET ("routing.allocation.total_shards_per_node");
The data movement takes place one replica at a time and there is no impact on querying of the event’s data while it is being moved, new data also continues to flow to the baseline nodes and its ingestion and querying are also not impacted.
We can monitor the progress of the data relocation querying sys.shards and sys.allocations.
Once all shards have moved away from the temporary nodes, we can decommission them gracefully:
ALTER CLUSTER DECOMMISSION 'nodename';
Once this is done, the machines can safely be shutdown.
Now, do i have to run set and reset command before node decomm,
ALTER TABLE test SET (“routing.allocation.exclude.storage” = ‘temporarynodes’);
ALTER TABLE test RESET (“routing.allocation.total_shards_per_node”);
I did not understand its complete meaning.