Incremental prepare with LSN

[Raghavendra D Prabhu]

For lp:1182094, specifically https://bugs.launchpad.net/percona-xtradb-cluster/+bug/1182094/comments/6, it helps if incremental prepare took incremental-lsn similar to incremental backup. From what I see, it only requires the 'to_lsn' of the basedir instance, also the last_lsn for consistency check.
If to_lsn is provided through incremental-lsn option (when
added), it would help in automatation of incremental SST.

[Alexey Kopytov (akopytov)]

I'm not sure I understand this. Is this to let users provide to_lsn manually when xtrabackup_checkpoints is not available?

If yes, then I'm inclined to close this as not a bug. xtrabackup_checkpoint is a part of the backup metadata. If there are use cases when it isn't available, perhaps we should reconsider when and it is created or change its format?

[Raghavendra D Prabhu (raghavendra-prabhu)]

xtrabackup_checkpoints file is not updated after it is once written on
the donor; from_lsn sure but to_lsn won't be the same after the joiner
server starts (joiner or any receiver of this incremental backup). Hence
providing this to_lsn will result in a failed incremental prepare.

Currently, the lsn needs to be manually obtained like:
        lsn=$(/pxc/bin/mysqld --defaults-file=$WSREP_SST_OPT_CONF --basedir=/pxc --wsrep-recover 2>&1 | grep -o 'log sequence number .*' | cut -d " " -f 4 | head -1)

        (or something equivalent)

and xtrabackup_checkpoints file's to_lsn needs to be manually
obtained with lsn obtained from previous step.

So, if instead lsn can be directly provided to
innobackupex/xtrabackup it would be better.

(It would also be better if xtrabackup can directly get the lsn,
but that is outside the scope of this bug)

[Alexey Kopytov (akopytov)]

Raghu,

I still don't understand the issue here. That's how I read it: so we have a full backup and a number of incremental ones on some host (is it a donor or a receiver?). Then we want to apply incremental ones to the full one (where?). But xtrabackup_checkpoints is not up-to-date (why?), so we need to have a way to specify it manually?

[Launchpad Janitor (janitor)]

[Expired for Percona XtraBackup because there has been no activity for 60 days.]

[Shahriyar Rzayev (rzayev-sehriyar)]

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PXB-1239