SST mysqldump --single-transaction

[Hoggins!]

Hi !

First post here, I've browsed the archives, and I'm not sure this hasn't
been discussed before :

I read that the only way to have an SST that does not block the DONOR
node is to use Xtrabackup.
Couldn't we imagine using mysqldump, but with the --single-transaction
argument addition, that would avoid locking ? Is there any way to
specify command-line arguments in the wsrep_sst_method config option ?

Thanks for your inputs.

Hoggins!

[Philip Stoev]

> I read that the only way to have an SST that does not block the DONOR
> node is to use Xtrabackup.
> Couldn't we imagine using mysqldump, but with the --single-transaction
> argument addition, that would avoid locking ? Is there any way to
> specify command-line arguments in the wsrep_sst_method config option ?

Hello,

Your suggestion is theoretically possible, however the following
considerations would apply:
* mysqldump --single-transaction does not provide a fully consistent
snapshot of the database. It can be disrupted by DDL statements that are
executed concurrently with it.
* mysqldump in general is not scalable as an SST mechanism, as loading the
dump onto the joiner node is slow. Switching from xtrabackup to a
non-donor-blocking mysqldump will trade more availability time on the donor
for less availability time on the joiner due to the longer joining time.

Philip Stoev


-----Original Message-----
From: Hoggins!
Sent: Wednesday, July 22, 2015 15:07
To: Codership
Subject: [codership-team] SST mysqldump --single-transaction

[Hoggins!]

Hello Philip,

Thanks for the explanation ! Now I'm trying to get Xtrabackup working on
Fedora machines.

Cheers !

Hoggins!

[James Wang]

Hi Nicolas,

Did you have performance issue with rsync which the default recommended (by Galera) for SST please?

Why do you want to change please?

Thanks in advance