Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

Attila Fazekas" > >> Cc: "OpenStack Development Mailing List (not for usage questions)" > >> , "Pavel > >> Kholkin" > >> Sent: Tuesday, February 10, 2015 7:32:11 PM > >> Subject: Re: [openstack-dev] [all][oslo.db][nova] TL;

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

enStack Development Mailing List (not for usage questions)" > >> , "Pavel > >> Kholkin" > >> Sent: Tuesday, February 10, 2015 7:32:11 PM > >> Subject: Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody > >> should

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

" Cc: "Pavel Kholkin" Sent: Monday, February 9, 2015 7:15:10 PM Subject: Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera On 02/09/2015 01:02 PM, Attila Fazekas wrote: I do not see why not to use `FOR UPDATE` even with multi-writer or Is

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

On 02/11/2015 07:58 AM, Matthew Booth wrote: On 10/02/15 18:29, Jay Pipes wrote: On 02/10/2015 09:47 AM, Matthew Booth wrote: On 09/02/15 18:15, Jay Pipes wrote: On 02/09/2015 01:02 PM, Attila Fazekas wrote: I do not see why not to use `FOR UPDATE` even with multi-writer or Is the retry/swap

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

On 10/02/15 18:29, Jay Pipes wrote: > On 02/10/2015 09:47 AM, Matthew Booth wrote: >> On 09/02/15 18:15, Jay Pipes wrote: >>> On 02/09/2015 01:02 PM, Attila Fazekas wrote: I do not see why not to use `FOR UPDATE` even with multi-writer or Is the retry/swap way really solves anything here.

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

t Mailing > >> List (not for usage questions)" > >> > >> Cc: "Pavel Kholkin" > >> Sent: Monday, February 9, 2015 7:15:10 PM > >> Subject: Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody > >> should know about Gal

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera On 02/09/2015 01:02 PM, Attila Fazekas wrote: I do not see why not to use `FOR UPDATE` even with multi-writer or Is the retry/swap way really solves anything here. Am I missed something ? Yes. Galera doe

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

On 02/10/2015 09:47 AM, Matthew Booth wrote: On 09/02/15 18:15, Jay Pipes wrote: On 02/09/2015 01:02 PM, Attila Fazekas wrote: I do not see why not to use `FOR UPDATE` even with multi-writer or Is the retry/swap way really solves anything here. Am I missed something ? Yes. Galera does not

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

On 09/02/15 18:15, Jay Pipes wrote: > On 02/09/2015 01:02 PM, Attila Fazekas wrote: >> I do not see why not to use `FOR UPDATE` even with multi-writer or >> Is the retry/swap way really solves anything here. > >> Am I missed something ? > > Yes. Galera does not replicate the (internal to InnnoDB)

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

- Original Message - > From: "Jay Pipes" > To: "Attila Fazekas" , "OpenStack Development Mailing > List (not for usage questions)" > > Cc: "Pavel Kholkin" > Sent: Monday, February 9, 2015 7:15:10 PM > Subject: Re:

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

- Original Message - > From: "Jay Pipes" > To: openstack-dev@lists.openstack.org > Sent: Monday, February 9, 2015 9:36:45 PM > Subject: Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody > should know about Galera > > On 02/09/2

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

On 02/09/2015 05:02 PM, Clint Byrum wrote: Excerpts from Jay Pipes's message of 2015-02-09 12:36:45 -0800: CAS is preferred because it is measurably faster and more obstruction-free than SELECT FOR UPDATE. A colleague of mine is almost ready to publish documentation showing a benchmark of this t

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

Excerpts from Jay Pipes's message of 2015-02-09 12:36:45 -0800: > CAS is preferred because it is measurably faster and more > obstruction-free than SELECT FOR UPDATE. A colleague of mine is almost > ready to publish documentation showing a benchmark of this that shows > nearly a 100% decrease in

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

On 02/09/2015 03:10 PM, Clint Byrum wrote: Excerpts from Jay Pipes's message of 2015-02-09 10:15:10 -0800: On 02/09/2015 01:02 PM, Attila Fazekas wrote: I do not see why not to use `FOR UPDATE` even with multi-writer or Is the retry/swap way really solves anything here. Am I missed something

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

Excerpts from Jay Pipes's message of 2015-02-09 10:15:10 -0800: > On 02/09/2015 01:02 PM, Attila Fazekas wrote: > > I do not see why not to use `FOR UPDATE` even with multi-writer or > > Is the retry/swap way really solves anything here. > > > Am I missed something ? > > Yes. Galera does not repl

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

On 02/09/2015 01:02 PM, Attila Fazekas wrote: I do not see why not to use `FOR UPDATE` even with multi-writer or Is the retry/swap way really solves anything here. Am I missed something ? Yes. Galera does not replicate the (internal to InnnoDB) row-level locks that are needed to support SEL

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

- Original Message - > From: "Jay Pipes" > To: openstack-dev@lists.openstack.org, "Pavel Kholkin" > Sent: Wednesday, February 4, 2015 8:04:10 PM > Subject: Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody > should know about Galera

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

Hi Angus, If causal reads is set in a session, it won't delay all reads, just that specific read that you set if for. Let's say you have 4 sessions, in one of them you set causal reads, the other 3 won't wait on anything. The read in the one session that you set this in will be delayed, in the oth

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

Thanks for the additional details Peter. This confirms the parts I'd deduced from the docs I could find, and is useful knowledge. On Sat Feb 07 2015 at 2:24:23 AM Peter Boros wrote: > > - Like many others said it before me, consistent reads can be achieved > with wsrep_causal_reads set on in the

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

Hi Angus and everyone, I would like to reply for a couple of things: - The behavior of overlapping transactions is dependent on the transaction isolation level, even in the case of the single server, for any database. This was pointed out by others earlier as well. - The deadlock error from Galer

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

On 5 February 2015 at 23:07, Clint Byrum wrote: > Excerpts from Avishay Traeger's message of 2015-02-04 22:19:53 -0800: > > On Wed, Feb 4, 2015 at 11:00 PM, Robert Collins < > robe...@robertcollins.net> > > wrote: > > > > > On 5 February 2015 at 10:24, Joshua Harlow > wrote: > > > > How interest

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

On 2015-02-05 9:36 PM, Angus Lees wrote: On Fri Feb 06 2015 at 12:59:13 PM Gregory Haynes mailto:g...@greghaynes.net>> wrote: Along those lines and in an effort to be a bit less doom-and-gloom, I spent my lunch break trying to find non-marketing documentation on the Galera replication protocol a

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

Excerpts from Angus Lees's message of 2015-02-06 02:36:32 +: > On Fri Feb 06 2015 at 12:59:13 PM Gregory Haynes > wrote: > > > Excerpts from Joshua Harlow's message of 2015-02-06 01:26:25 +: > > > Angus Lees wrote: > > > > On Fri Feb 06 2015 at 4:25:43 AM Clint Byrum > > >

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

On Fri Feb 06 2015 at 12:59:13 PM Gregory Haynes wrote: > Excerpts from Joshua Harlow's message of 2015-02-06 01:26:25 +: > > Angus Lees wrote: > > > On Fri Feb 06 2015 at 4:25:43 AM Clint Byrum > > > wrote: > > > I'd also like to see consideration given to syste

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

Excerpts from Joshua Harlow's message of 2015-02-06 01:26:25 +: > Angus Lees wrote: > > On Fri Feb 06 2015 at 4:25:43 AM Clint Byrum > > wrote: > > I'd also like to see consideration given to systems that handle > > distributed consistency in a more active mann

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

Angus Lees wrote: On Fri Feb 06 2015 at 4:25:43 AM Clint Byrum mailto:cl...@fewbar.com>> wrote: In a single thread, using a single database session, then a read after successful commit is guaranteed to read a version of the database that existed after that commit. Ah, I'm relieved

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

On Fri Feb 06 2015 at 4:25:43 AM Clint Byrum wrote: > > In a single thread, using a single database session, then a read after > successful commit is guaranteed to read a version of the database > that existed after that commit. > Ah, I'm relieved to hear this clarification - thanks. I'd like to

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

Hey now you forgot a site in that list ;-) -Josh Clint Byrum wrote: You may want to have a chat with the people running MySQL at Google, Facebook, and a long tail of not quite as big sites but still massively bigger than most clouds. ___

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

Excerpts from Avishay Traeger's message of 2015-02-04 22:19:53 -0800: > On Wed, Feb 4, 2015 at 11:00 PM, Robert Collins > wrote: > > > On 5 February 2015 at 10:24, Joshua Harlow wrote: > > > How interesting, > > > > > > Why are people using galera if it behaves like this? :-/ > > > > Because its

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

Excerpts from Angus Lees's message of 2015-02-04 16:59:31 -0800: > On Thu Feb 05 2015 at 9:02:49 AM Robert Collins > wrote: > > > On 5 February 2015 at 10:24, Joshua Harlow wrote: > > > How interesting, > > > > > > Why are people using galera if it behaves like this? :-/ > > > > Because its actu

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

/refman/5.0/en/innodb-deadlocks.html > > - Original Message - >> From: "Matthew Booth" >> To: openstack-dev@lists.openstack.org >> Sent: Thursday, February 5, 2015 10:36:55 AM >> Subject: Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everyb

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

- Original Message - > From: "Matthew Booth" > To: openstack-dev@lists.openstack.org > Sent: Thursday, February 5, 2015 12:32:33 PM > Subject: Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody > should know about Galera > > On 05/02

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

On 05/02/15 11:11, Sahid Orentino Ferdjaoui wrote: >> I'm still confused as to how this code got there, though. We shouldn't >> be hitting Galera lock contention (reported as deadlocks) if we're using >> a single master, which I thought we were. Does this mean either: > > I guess we can hit a lock

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

On 05/02/15 11:01, Attila Fazekas wrote: > I have a question related to deadlock handling as well. > > Why the DBDeadlock exception is not caught generally for all api/rpc request ? > > The mysql recommendation regarding to Deadlocks [1]: > "Normally, you must write your applications so that they

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

On Thu, Feb 05, 2015 at 09:56:21AM +, Matthew Booth wrote: > On 04/02/15 19:04, Jay Pipes wrote: > > On 02/04/2015 12:05 PM, Sahid Orentino Ferdjaoui wrote: > >> On Wed, Feb 04, 2015 at 04:30:32PM +, Matthew Booth wrote: > >>> I've spent a few hours today reading about Galera, a clustering

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

enstack-dev] [all][oslo.db][nova] TL; DR Things everybody > should know about Galera > > On 04/02/15 17:05, Sahid Orentino Ferdjaoui wrote: > >> * Commit will fail if there is a replication conflict > >> > >> foo is a table with a single field, which is its pr

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

On 05/02/15 04:30, Mike Bayer wrote: >> Galera doesn't change anything here. I'm really not sure what the >> fuss is about, frankly. > > because we’re trying to get Galera to actually work as a load > balanced cluster to some degree, at least for reads. Yeah, the use case of concern here is conse

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

On 04/02/15 19:04, Jay Pipes wrote: > On 02/04/2015 12:05 PM, Sahid Orentino Ferdjaoui wrote: >> On Wed, Feb 04, 2015 at 04:30:32PM +, Matthew Booth wrote: >>> I've spent a few hours today reading about Galera, a clustering solution >>> for MySQL. Galera provides multi-master 'virtually synchro

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

On 04/02/15 17:05, Sahid Orentino Ferdjaoui wrote: >> * Commit will fail if there is a replication conflict >> >> foo is a table with a single field, which is its primary key. >> >> A: start transaction; >> B: start transaction; >> A: insert into foo values(1); >> B: insert into foo values(1); <--

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

On Wed, Feb 4, 2015 at 11:00 PM, Robert Collins wrote: > On 5 February 2015 at 10:24, Joshua Harlow wrote: > > How interesting, > > > > Why are people using galera if it behaves like this? :-/ > > Because its actually fairly normal. In fact its an instance of point 7 > on https://wiki.openstack.

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

Jay Pipes wrote: > No, this is not correct. There is nothing different about Galera here versus > any asynchronously replicated database. A single thread, issuing statements > in two entirely *separate sessions*, load-balanced across an entire set of > database cluster nodes, may indeed see

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

On 02/04/2015 07:59 PM, Angus Lees wrote: On Thu Feb 05 2015 at 9:02:49 AM Robert Collins mailto:robe...@robertcollins.net>> wrote: On 5 February 2015 at 10:24, Joshua Harlow mailto:harlo...@outlook.com>> wrote: > How interesting, > > Why are people using galera if it behave

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

On Thu Feb 05 2015 at 9:02:49 AM Robert Collins wrote: > On 5 February 2015 at 10:24, Joshua Harlow wrote: > > How interesting, > > > > Why are people using galera if it behaves like this? :-/ > > Because its actually fairly normal. In fact its an instance of point 7 > on https://wiki.openstack.

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

Excerpts from Joshua Harlow's message of 2015-02-04 13:24:20 -0800: > How interesting, > > Why are people using galera if it behaves like this? :-/ > Note that any true MVCC database will roll back transactions on conflicts. One must always have a deadlock detection algorithm of some kind. Gale

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

On 5 February 2015 at 10:24, Joshua Harlow wrote: > How interesting, > > Why are people using galera if it behaves like this? :-/ Because its actually fairly normal. In fact its an instance of point 7 on https://wiki.openstack.org/wiki/BasicDesignTenets - one of our oldest wiki pages :). In more

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

Excerpts from Matthew Booth's message of 2015-02-04 08:30:32 -0800: > * Write followed by read on a different node can return stale data > > During a commit, Galera replicates a transaction out to all other db > nodes. Due to its design, Galera knows these transactions will be > successfully commi

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

How interesting, Why are people using galera if it behaves like this? :-/ Are the people that are using it know/aware that this happens? :-/ Scary Mike Bayer wrote: Matthew Booth wrote: A: start transaction; A: insert into foo values(1) A: commit; B: select * from foo;<-- May not cont

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

Matthew Booth wrote: > A: start transaction; > A: insert into foo values(1) > A: commit; > B: select * from foo; <-- May not contain the value we inserted above[3] I’ve confirmed in my own testing that this is accurate. the wsrep_causal_reads flag does resolve this, and it is settable on a per

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

On 02/04/2015 12:05 PM, Sahid Orentino Ferdjaoui wrote: On Wed, Feb 04, 2015 at 04:30:32PM +, Matthew Booth wrote: I've spent a few hours today reading about Galera, a clustering solution for MySQL. Galera provides multi-master 'virtually synchronous' replication between multiple mysql nodes

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

Matthew Booth wrote: > This means that even for 'synchronous' slaves, if a client makes an RPC > call which writes a row to write master A, then another RPC call which > expects to read that row from synchronous slave node B, there's no > default guarantee that it'll be there. Can I get some

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

Matthew Booth wrote: > A: start transaction; > B: start transaction; > A: insert into foo values(1); > B: insert into foo values(1); <-- 'regular' DB would block here, and > report an error on A's commit > A: commit; <-- success > B: commit; <-- KABOOM > > Conf

Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

On Wed, Feb 04, 2015 at 04:30:32PM +, Matthew Booth wrote: > I've spent a few hours today reading about Galera, a clustering solution > for MySQL. Galera provides multi-master 'virtually synchronous' > replication between multiple mysql nodes. i.e. I can create a cluster of > 3 mysql dbs and re

[openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera

I've spent a few hours today reading about Galera, a clustering solution for MySQL. Galera provides multi-master 'virtually synchronous' replication between multiple mysql nodes. i.e. I can create a cluster of 3 mysql dbs and read and write from any of them with certain consistency guarantees. I a