Allow non-superusers to run certain ALTER CLUSTER commands

Use case: As a Admin-user I want to also often want to run certain administrative commands, since often I can’t directly connect to the host of CrateDB (e.g. as only ports 5432 / 4200 are accessible). Also e.g. ALTER CLUSTER SWAP TABLE is useful, I one would want to simulate a materialised view behaviour

CREATE TABLE m_view_new AS SELECT ...
INSERT INTO TABLE m_view SELECT ... FROM source
ALTER CLUSTER SWAP TABLE m_view_new to m_view;
DROP TABLE m_view_new;

Also ALTER CLUSTER SWAP TABLE would be useful anyway for normal users.

Feature description:

Allow the following commands for non-superusers with admin-rights AL:

ALTER CLUSTER SWAP TABLE source TO target [ WITH ( expr = expr [ , ... ] ) ]
ALTER CLUSTER REROUTE RETRY FAILED
ALTER CLUSTER GC DANGLING ARTIFACTS

other commands should still require super-user rights e.g. decommission as one would expect access to the hosts anyway

ALTER CLUSTER DECOMMISSION <nodeId | nodeName>

[proddata]

Any user with AL privileges (they are always on cluster level. Not to be confused with ALL)

I think crate as super user has all privileges 🤔

@BaurzhanSakhariev

Administration Language (AL)

[BaurzhanSakhariev]

For consistency, I would think that only allow those ALTER CLUSTER operations to AL

+1 to only AL

@mfussenegger, does SWAP TABLES simply change table names so that whenever we refer to B after the swap it will just go to former A object? I couldn’t find anything about columns/schema correspondence or validation so I don’t think data migration is happening.

I just realized that to really achieve effect of fully swapping objects, i.e make B look exactly like A and vice versa, one needs to drop redundant columns from B, add lacking columns from A into B (DDL on B) + DQL on A, DML on B. ==> even if we don’t need create table B we still need DDL on B. Also, even if dropSource == false, still need DDL on A to add/remove columns from B

probably it really makes sense just to keep AL - yes, users with required D* privileges can accomplish that, but if I’m right about swap = absolute replacement than nobody would do it in such a tricky way with adding/removing columns