Require lockless backup

[MikeG]

It would be nice to have an option where you require that the backup fail if it can not be completed without locking. There are cases where I would rather have no backup for the night than downtime.

An example would be a database which is pure innodb having a new table accidentally created as MyISAM. Ordinarily this would just downgrade from --single-transaction to --lock-tables but it would be nice to have an option where instead the backup refuses to start until the table is converted to a transactional engine.

[Andrew Garner (muzazzi)]

I added a lockless-only = yes|no option to mysqldump in my amsterdam (holland1.1) tree here:

https://github.com/abg/holland/blob/amsterdam/plugins/holland.backup.mysqldump/holland/backup/mysqldump/spec.py

This will abort the backup if holland-mysqldump would use --lock-tables (i.e. a table in some non-excluded database is non-transactional). This will output something like:

[ERROR] Database 'test' has one or more non-transactional tables:
[ERROR] * test.foo is non-transactional (engine=MyISAM)
[INFO] Backup 'mysqldump' failed: One or more databases had non-transactional tables that would result in a locking backup but lockless-only was requested. Aborting backup.

[Andrew Garner (muzazzi)]

Merged into amsterdam branch here:

https://github.com/holland-backup/holland/tree/98feea3930159bdee5fa2ddbae7dc79f1530212b