Add BACKUP new command with options

[aleksraiden]

Search before asking

• I had searched in the issues and found no similar issues.

Motivation

At now we have only BGSAVE command (for compatibility with original Redis semantic), and need a separate SET config options for backup_path. And, as I see, not supporting sync/async mode of backup.

Solution

Command BGSAVE hasn't clear semantic, so I propose a new command: BACKUP <backup_path> SYNC|ASYNC

• <backup_path> are optional path to store current backup (e.g. /tmp/backup etc.) If backup are exists, it will be destroy before perform a new.
• SYNC|ASYNC is an option flag (default are ASYNC) for creating backup using sync/async method (see BackupableDBOptions::sync

Are you willing to submit a PR?

• I'm willing to submit a PR!

[aleksraiden]

A some internal discussion are here - #483

[git-hulk]

Hi @aleksraiden

I think it's a good proposal, I even think if possible to backup and restore from the remote storage directly. https://github.com/orgs/apache/projects/199?pane=issue&itemId=23218575