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

2015-02-12 Thread Attila Fazekas
: Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera - Original Message - From: Jay Pipes jaypi...@gmail.com To: Attila Fazekas afaze...@redhat.com Cc: OpenStack Development Mailing List (not for usage questions) openstack-dev

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

2015-02-12 Thread Attila Fazekas
Subject: Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera On 02/11/2015 06:34 AM, Attila Fazekas wrote: - Original Message - From: Jay Pipes jaypi...@gmail.com To: Attila Fazekas afaze...@redhat.com Cc: OpenStack Development Mailing List

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

2015-02-11 Thread Jay Pipes
: Tuesday, February 10, 2015 7:32:11 PM Subject: Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera On 02/10/2015 06:28 AM, Attila Fazekas wrote: - Original Message - From: Jay Pipes jaypi...@gmail.com To: Attila Fazekas afaze...@redhat.com, OpenStack

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

2015-02-11 Thread Jay Pipes
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

2015-02-11 Thread Attila Fazekas
Subject: Re: [openstack-dev] [all][oslo.db][nova] TL; DR Things everybody should know about Galera On 02/10/2015 06:28 AM, Attila Fazekas wrote: - Original Message - From: Jay Pipes jaypi...@gmail.com To: Attila Fazekas afaze...@redhat.com, OpenStack Development Mailing List

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

2015-02-11 Thread Matthew Booth
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. snip Am I

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

2015-02-10 Thread Matthew Booth
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. snip 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

2015-02-10 Thread Attila Fazekas
- Original Message - From: Jay Pipes jaypi...@gmail.com 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 02/09/2015 03:10 PM, Clint Byrum wrote

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

2015-02-10 Thread Attila Fazekas
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 the retry/swap way really solves anything here. snip Am I missed something

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

2015-02-10 Thread Jay Pipes
: 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 the retry/swap way really solves anything here

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

2015-02-10 Thread Jay Pipes
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. snip Am I missed something ? Yes. Galera does

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

2015-02-09 Thread Attila Fazekas
- Original Message - From: Jay Pipes jaypi...@gmail.com To: openstack-dev@lists.openstack.org, Pavel Kholkin pkhol...@mirantis.com 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

2015-02-09 Thread Jay Pipes
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. snip Am I missed something ? Yes. Galera does not replicate the (internal to InnnoDB) row-level locks that are needed to

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

2015-02-09 Thread Jay Pipes
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. snip Am I missed

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

2015-02-09 Thread Clint Byrum
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

2015-02-09 Thread Clint Byrum
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. snip Am I missed something ? Yes. Galera does not replicate

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

2015-02-09 Thread Jay Pipes
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

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

2015-02-07 Thread Peter Boros
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

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

2015-02-06 Thread Angus Lees
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 peter.bo...@percona.com wrote: - Like many others said it before me, consistent reads can be achieved with

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

2015-02-06 Thread Peter Boros
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

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

2015-02-05 Thread Rushi Agrawal
On 5 February 2015 at 23:07, Clint Byrum cl...@fewbar.com 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 harlo...@outlook.com

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

2015-02-05 Thread Attila Fazekas
- Original Message - From: Matthew Booth mbo...@redhat.com 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 05/02/15 11:01, Attila Fazekas

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

2015-02-05 Thread Matthew Booth
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 synchronous'

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

2015-02-05 Thread Matthew Booth
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

2015-02-05 Thread Clint Byrum
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 robe...@robertcollins.net wrote: On 5 February 2015 at 10:24, Joshua Harlow harlo...@outlook.com wrote: How interesting, Why are people using galera if it behaves like

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

2015-02-05 Thread Clint Byrum
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 harlo...@outlook.com wrote: How interesting, Why are people using galera if it behaves

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

2015-02-05 Thread Mike Bayer
...@redhat.com 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 everybody should know about Galera On 04/02/15 17:05, Sahid Orentino Ferdjaoui wrote: * Commit will fail if there is a replication

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

2015-02-05 Thread Angus Lees
On Fri Feb 06 2015 at 4:25:43 AM Clint Byrum 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 to hear this clarification - thanks.

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

2015-02-05 Thread Joshua Harlow
Angus Lees wrote: On Fri Feb 06 2015 at 4:25:43 AM Clint Byrum cl...@fewbar.com 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.

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

2015-02-05 Thread Gregory Haynes
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 cl...@fewbar.com mailto:cl...@fewbar.com wrote: I'd also like to see consideration given to systems that handle distributed consistency in a more

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

2015-02-05 Thread Sahid Orentino Ferdjaoui
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 solution

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

2015-02-05 Thread Matthew Booth
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 consecutive

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

2015-02-05 Thread Attila Fazekas
][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

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

2015-02-05 Thread Matthew Booth
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 are

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

2015-02-05 Thread Matthew Booth
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); -- 'regular' DB

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

2015-02-05 Thread Angus Lees
On Fri Feb 06 2015 at 12:59:13 PM Gregory Haynes g...@greghaynes.net 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 cl...@fewbar.com mailto:cl...@fewbar.com wrote: I'd also like to see

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

2015-02-05 Thread Gregory Haynes
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 g...@greghaynes.net 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

2015-02-05 Thread Mathieu Gagné
On 2015-02-05 9:36 PM, Angus Lees wrote: On Fri Feb 06 2015 at 12:59:13 PM Gregory Haynes g...@greghaynes.net 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

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

2015-02-05 Thread Joshua Harlow
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

2015-02-04 Thread Sahid Orentino Ferdjaoui
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 read

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

2015-02-04 Thread Mike Bayer
Matthew Booth mbo...@redhat.com 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.

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

2015-02-04 Thread Jay Pipes
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

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

2015-02-04 Thread Mike Bayer
Matthew Booth mbo...@redhat.com 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

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

2015-02-04 Thread Clint Byrum
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 committed

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

2015-02-04 Thread Joshua Harlow
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 Boothmbo...@redhat.com wrote: A: start transaction; A: insert into foo values(1) A: commit; B: select * from

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

2015-02-04 Thread Clint Byrum
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. Galera

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

2015-02-04 Thread Robert Collins
On 5 February 2015 at 10:24, Joshua Harlow harlo...@outlook.com 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

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

2015-02-04 Thread Mike Bayer
Matthew Booth mbo...@redhat.com 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

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

2015-02-04 Thread Jay Pipes
On 02/04/2015 07:59 PM, Angus Lees wrote: On Thu Feb 05 2015 at 9:02:49 AM Robert Collins robe...@robertcollins.net mailto:robe...@robertcollins.net wrote: On 5 February 2015 at 10:24, Joshua Harlow harlo...@outlook.com mailto:harlo...@outlook.com wrote: How interesting,

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

2015-02-04 Thread Avishay Traeger
On Wed, Feb 4, 2015 at 11:00 PM, Robert Collins robe...@robertcollins.net wrote: On 5 February 2015 at 10:24, Joshua Harlow harlo...@outlook.com wrote: How interesting, Why are people using galera if it behaves like this? :-/ Because its actually fairly normal. In fact its an instance of

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

2015-02-04 Thread Angus Lees
On Thu Feb 05 2015 at 9:02:49 AM Robert Collins robe...@robertcollins.net wrote: On 5 February 2015 at 10:24, Joshua Harlow harlo...@outlook.com wrote: How interesting, Why are people using galera if it behaves like this? :-/ Because its actually fairly normal. In fact its an instance of

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

2015-02-04 Thread Mike Bayer
Jay Pipes jaypi...@gmail.com 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,