In mariadb-backup --backup there are multiple mechanisms for ensuring that
a sufficient amount of the InnoDB write-ahead log (ib_logfile0) is being
copied at the end of the backup. The backup needs to include the latest
committed transaction. While further transaction commits are blocked by
BACKUP STAGE BLOCK_COMMIT, ongoing transactions may modify the database
contents and write log records. We were unnecessarily copying such log,
which would also cause further effort of rolling back incomplete
transactions after the backup is restored.
backup_wait_for_lsn(): Declare as static, and refactor some code
to separate functions backup_wait_for_lsn_low() and
backup_wait_timeout().
backup_wait_for_commit_lsn(): A new function to determine the current
LSN (within BACKUP STAGE BLOCK_COMMIT) and to wait for the log to be
copied until that. Invoked by BackupStages::stage_block_commit().
xtrabackup_backup_func(): Remove a condition that had already been
checked by a caller of backup_wait_timeout().
server_lsn_after_lock: Declare as a local variable in
BackupStages::stage_block_ddl().
log_copying_thread(), io_watching_thread(): Use metadata_last_lsn
instead of metadata_to_lsn as the stop condition.
BackupStages::stage_block_commit(): Ensure that the log tables
(in particular, mysql.general_log) will have been copied before
the BACKUP STAGE BLOCK_COMMIT is being followed by any further
SQL statements.
Reviewed by: Debarun Banerjee
Tested by: Matthias Leich
Added support to BACKUP STAGE to maria-backup
This is a port of the code from ES 10.6
See MDEV-5336 for backup stages description.
The following old options are not supported by the new code:
--rsync ; This is because rsync will not work on tables
that are in used.
--no-backup-locks ; This is disabled as mariadb-backup will always
use backup locks for better performance.
