ingesting: fixup privileges granted during database restore

[adityamaru]

Previously, all schemas and tables that were ingested as part of a database restore would "inherit" the privileges of the database. The database would be granted CONNECT for the public role and ALL to admin and root, and so all ingested schemas would have ALL for admin and root. Since 21.2 we have moved away from tables/schemas inheriting privileges from the parent database and so this logic is stale and partly incorrect. It is incorrect because the restored public schema does not have CREATE and USAGE granted to the public role. These privileges are always granted to public schemas of a database and so there is a discrepancy in restore's behaviour.

This change simplifies the logic to grant schemas and tables their default set of privileges if ingested via a database restore. It leaves the logic for cluster and table restores unchanged.

Release note (bug fix): fixes a bug where a database restore would not grant CREATE and USAGE on the public schema to the public role

Fixes: #95456

[cockroach-teamcity]

This change is 

[rafiss]

thanks for the fix!

[adityamaru]

Flake is /cockroach-go-testserver-22_1-22_2_test that is being tracked elsewhere.

TFTR!

bors r=rafiss

[data-matt]

@adityamaru , does it grant CREATE/USAGE to public role blindly?

We have customers revoking CREATE and USAGE from the public role

[adityamaru]

does it grant CREATE/USAGE to public role blindly

Yes, a database restore will now grant CREATE/USAGE on the public schema to the public role. This is in line with what happens if you were to create a database using CREATE DATABASE so restores behavior was irregular.

[data-matt]

I don't think thats a great idea, that will create surprises.

Imagine you are a user.

You revoke from this access from the public role.

You restore and CREATE/USAGE comes back..

[craig]

Build failed (retrying...):

• Bazel Essential CI (Cockroach)

[adityamaru]

You revoke from this access from the public role.

When a user revokes these privileges it will be from a public schema of an existing database foo. They will not be able to restore database foo without dropping database foo before running the restore. Instead of a restore, had they run CREATE DATABASE foo after the drop they would also end up with a foo.public schema with public having CREATE and USAGE. So I'm not sure I follow how we're expanding the privilege set after the user has revoked them.
A restore is essentially a CREATE + backfill of data.

[rafiss]

@data-matt one thing to clarify: for a cluster-level RESTORE, all entities and privileges on those entities will be restored exactly as they were at the time of the BACKUP.

But this PR is for the database RESTORE. The scenario you are describing also applies to tables. (If a customer had granted privileges on a table, then does a database RESTORE, the tables will be created with the default privileges and the custom grants will be lost. Is my understanding right @adityamaru?)

[data-matt]

Yeah, I realised my point is moot, since we only restore grants for full cluster backups. So, the users have an action to put the grants back anyway. Please ignore me :D

[craig]

Build succeeded:

• Bazel Essential CI (Cockroach)

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