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.
This is a non-functional change.
simplifying the code logic:
- removing global variables ds_data and ds_meta
- passing these variables as parameters to functions instead
- adding helper classes: Datasink_free_list and Backup_datasinks
- moving some function accepting a ds_ctxt parameter
as methods to ds_ctxt.
trx_sys_t::undo_log_nonempty: Set to true if there are undo logs
to rollback and purge.
The algorithm for re-creating the undo tablespace when
trx_sys_t::undo_log_nonempty is disabled:
1) trx_sys_t::reset_page(): Reset the TRX_SYS page and assign all
rollback segment slots from 1..127 to FIL_NULL
2) Free the rollback segment header page of system tablespace
for the slots 1..127
3) Update the binlog and WSREP information in system tablespace
rollback segment header
Step (1), (2) and Step (3) should happen atomically within a
single mini-transaction.
4) srv_undo_delete_old_tablespaces(): Delete the old undo tablespaces
present in the undo log directory
5) Make checkpoint to get rid of old undo log tablespaces redo logs
6) Assign new start space id for the undo log tablespaces
7) Re-create the specified undo log tablespaces. InnoDB uses same
mtr for this one and step (6)
8) Make checkpoint again, so that server or mariabackup
can read the undo log tablespace page0 before applying
the redo logs
srv_undo_tablespaces_reinit(): Recreate the undo log tablespaces.
It does reset trx_sys page, delete the old undo tablespaces,
update the binlog offset, write set replication checkpoint
in system rollback segment page
trx_rseg_update_binlog_offset(): Added 2 new parameters to pass
binlog file name and binlog offset
trx_rseg_array_init(): Return error if the rollback segment
slot points to non-existent tablespace
srv_undo_tablespaces_init(): Added new parameter mtr
to initialize all undo tablespaces
trx_assign_rseg_low(): Allow the transaction to use the rollback
segment slots(1..127) even if InnoDB failed to change to the
requested innodb_undo_tablespaces=0
srv_start(): Override the user specified value of
innodb_undo_tablespaces variable with already existing actual
undo tablespaces
wf_incremental_process(): Detects whether TRX_SYS page has been
modified since last backup. If it is then incremental backup
fails and throws the information about taking full backup again
xb_assign_undo_space_start(): Removed the function. Because
undo001 has first undo space id value in page0
Added test case to test the scenario during startup and mariabackup
incremental process too.
Reviewed-by : Marko Mäkelä
Tested-by : Matthias Leich
In the InnoDB data files, we allocate 32 bits for tablespace identifiers
and page numbers as well as tablespace flags. But, in main memory
data structures we allocate 32 or 64 bits, depending on the register
width of the processor. Let us always use 32-bit fields to eliminate
a mismatch and reduce the memory footprint on 64-bit systems.
The new option --log-innodb-page-corruption is introduced.
When this option is set, backup is not interrupted if innodb corrupted
page is detected. Instead it logs all found corrupted pages in
innodb_corrupted_pages file in backup directory and finishes with error.
For incremental backup corrupted pages are also copied to .delta file,
because we can't do LSN check for such pages during backup,
innodb_corrupted_pages will also be created in incremental backup
directory.
During --prepare, corrupted pages list is read from the file just after
redo log is applied, and each page from the list is checked if it is allocated
in it's tablespace or not. If it is not allocated, then it is zeroed out,
flushed to the tablespace and removed from the list. If all pages are removed
from the list, then --prepare is finished successfully and
innodb_corrupted_pages file is removed from backup directory. Otherwise
--prepare is finished with error message and innodb_corrupted_pages contains
the list of the pages, which are detected as corrupted during backup, and are
allocated in their tablespaces, what means backup directory contains corrupted
innodb pages, and backup can not be considered as consistent.
For incremental --prepare corrupted pages from .delta files are applied
to the base backup, innodb_corrupted_pages is read from both base in
incremental directories, and the same action is proceded for corrupted
pages list as for full --prepare. innodb_corrupted_pages file is
modified or removed only in base directory.
If DDL happens during backup, it is also processed at the end of backup
to have correct tablespace names in innodb_corrupted_pages.
MySQL 5.7 introduced the class page_size_t and increased the size of
buffer pool page descriptors by introducing this object to them.
Maybe the intention of this exercise was to prepare for a future
where the buffer pool could accommodate multiple page sizes.
But that future never arrived, not even in MySQL 8.0. It is much
easier to manage a pool of a single page size, and typically all
storage devices of an InnoDB instance benefit from using the same
page size.
Let us remove page_size_t from MariaDB Server. This will make it
easier to remove support for ROW_FORMAT=COMPRESSED (or make it a
compile-time option) in the future, just by removing various
occurrences of zip_size.
Some innobase/xtrabackup changes around from 10.1 are null merged
, in partucular using os_set_file_size to extend tablespaces in server
or mariabackup.
They require non-trivial amount of additional work in 10.2, due to
innobase differences between 10.1 and 10.2
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.
