• Marko Mäkelä's avatar
    MDEV-12548 Initial implementation of Mariabackup for MariaDB 10.2 · 8c71c6aa
    Marko Mäkelä authored
    InnoDB I/O and buffer pool interfaces and the redo log format
    have been changed between MariaDB 10.1 and 10.2, and the backup
    code has to be adjusted accordingly.
    
    The code has been simplified, and many memory leaks have been fixed.
    Instead of the file name xtrabackup_logfile, the file name ib_logfile0
    is being used for the copy of the redo log. Unnecessary InnoDB startup and
    shutdown and some unnecessary threads have been removed.
    
    Some help was provided by Vladislav Vaintroub.
    
    Parameters have been cleaned up and aligned with those of MariaDB 10.2.
    
    The --dbug option has been added, so that in debug builds,
    --dbug=d,ib_log can be specified to enable diagnostic messages
    for processing redo log entries.
    
    By default, innodb_doublewrite=OFF, so that --prepare works faster.
    If more crash-safety for --prepare is needed, double buffering
    can be enabled.
    
    The parameter innodb_log_checksums=OFF can be used to ignore redo log
    checksums in --backup.
    
    Some messages have been cleaned up.
    Unless --export is specified, Mariabackup will not deal with undo log.
    The InnoDB mini-transaction redo log is not only about user-level
    transactions; it is actually about mini-transactions. To avoid confusion,
    call it the redo log, not transaction log.
    
    We disable any undo log processing in --prepare.
    
    Because MariaDB 10.2 supports indexed virtual columns, the
    undo log processing would need to be able to evaluate virtual column
    expressions. To reduce the amount of code dependencies, we will not
    process any undo log in prepare.
    
    This means that the --export option must be disabled for now.
    
    This also means that the following options are redundant
    and have been removed:
    	xtrabackup --apply-log-only
    	innobackupex --redo-only
    
    In addition to disabling any undo log processing, we will disable any
    further changes to data pages during --prepare, including the change
    buffer merge. This means that restoring incremental backups should
    reliably work even when change buffering is being used on the server.
    Because of this, preparing a backup will not generate any further
    redo log, and the redo log file can be safely deleted. (If the
    --export option is enabled in the future, it must generate redo log
    when processing undo logs and buffered changes.)
    
    In --prepare, we cannot easily know if a partial backup was used,
    especially when restoring a series of incremental backups. So, we
    simply warn about any missing files, and ignore the redo log for them.
    
    FIXME: Enable the --export option.
    
    FIXME: Improve the handling of the MLOG_INDEX_LOAD record, and write
    a test that initiates a backup while an ALGORITHM=INPLACE operation
    is creating indexes or rebuilding a table. An error should be detected
    when preparing the backup.
    
    FIXME: In --incremental --prepare, xtrabackup_apply_delta() should
    ensure that if FSP_SIZE is modified, the file size will be adjusted
    accordingly.
    8c71c6aa
xb0xb.h 1011 Bytes