In case you have different roles for the same user on multiple clusters,
ON CLUSTER query can help to overcome some limitations.
Consider the following example:
- cluster_with_data, dev_user (readonly=2)
- stage_cluster, dev_user (readonly=0)
So when you will execute the following query from stage_cluster, it will
be successfully executed, since ON CLUSTER queries has different system
profile:
DROP DATABASE default ON CLUSTER cluster_with_data
This is not 100% safe, but at least something.
Note, that right now only ON CLUSTER query it self is supported, but
separate clusters are not (i.e. GRANT CLUSTER some_cluster_name TO
default), since right now grants sticked to database+.
v2: on_cluster_queries_require_cluster_grant
v3: fix test and process flags as bit mask
Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>