Before this patch there was:
- parallel_distributed_insert_select=1, that executes:
INSERT INTO dist_out SELECT ... FROM underlying_dist_in
After this patch there will be:
- parallel_distributed_insert_select=2, that executes:
INSERT INTO underlying_dist_out SELECT ... FROM underlying_dist_in
And cover the behaviour w/o integration test, by using the following
techincs:
- SYSTEM STOP DISTRIBUTED SENDS
- prefer_localhost_replica=0
