Clarify RESTORE docs

[lnhsingh]

Lauren Hirata Singh (lnhsingh) commented:

1. Is it possible to use into_db when restoring multiple databases?

No. In fact, it looks like you can’t use into_db when restoring databases at all. That option seems to only be available when specifying a table pattern. You can’t restore a database into another database, but you can restore its contents (db.*)

2. The docs for restoring a database seem to be inconsistent:
   "To restore a database, the database cannot already exist in the target cluster. Restoring a database will create the database and restore all of its tables and views. By default, tables and views are restored into a database with the name of the database from which they were backed up. However, also consider:

• You can choose to change the target database.
• If it no longer exists, you must create the target database.
  The target database must have not have tables or views with the same name as the tables or views you’re restoring."
  The first sentence says the database being restored cannot already exist in the target cluster. But later it says you must create the target database.

3. Is there any difference between RESTORE DATABASE foo and RESTORE TABLE foo.*?

The former also restores the db desc. So former db foo must not exist (because you’re restoring it), later it must exist because you’re restoring child objects into it

4. When restoring an incremental backup, do I have to specify both the full backup and all of the incrementals between the full and the incremental I want to restore?

Yes, need to specify every layer (when using explicit layers, as opposed to 20.1+ “appended” backups that store layers internally). Backupper only ever does one incremental layer which is why you just see one there. I.e. instead of fl -> a -> b -> c, backupper does fl -> a, fl -> b, fl -> c, so every inc backup (re)captures all changes since base backup (so eg the changes from 0:00 to 1:00 are backed up 23 times)

Slack convo(s) here

cc @mwang1026

Jira Issue: DOC-792