So this rings odd to me. If you can accomplish the same thing by using a CAS operation, why not fix create table if not exist so that if your are writing an application that creates the table on startup, that the application is safe to run on multiple nodes and uses CAS to safeguard multiple concurrent creations?
On Tue, Jan 26, 2016 at 12:32 PM, Eric Stevens <migh...@gmail.com> wrote: > There's still a race condition there, because two clients could SELECT at > the same time as each other, then both INSERT. > > You'd be better served with a CAS operation, and let Paxos guarantee > at-most-once execution. > > On Tue, Jan 26, 2016 at 9:06 AM Francisco Reyes <li...@natserv.net> wrote: > >> On 01/22/2016 10:29 PM, Kevin Burton wrote: >> >> I sort of agree.. but we are also considering migrating to hourly >> tables.. and what if the single script doesn't run. >> >> I like having N nodes make changes like this because in my experience >> that central / single box will usually fail at the wrong time :-/ >> >> >> >> On Fri, Jan 22, 2016 at 6:47 PM, Jonathan Haddad <j...@jonhaddad.com> >> wrote: >> >>> Instead of using ZK, why not solve your concurrency problem by removing >>> it? By that, I mean simply have 1 process that creates all your tables >>> instead of creating a race condition intentionally? >>> >>> On Fri, Jan 22, 2016 at 6:16 PM Kevin Burton <bur...@spinn3r.com> wrote: >>> >>>> Not sure if this is a bug or not or kind of a *fuzzy* area. >>>> >>>> In 2.0 this worked fine. >>>> >>>> We have a bunch of automated scripts that go through and create >>>> tables... one per day. >>>> >>>> at midnight UTC our entire CQL went offline.. .took down our whole app. >>>> ;-/ >>>> >>>> The resolution was a full CQL shut down and then a drop table to remove >>>> the bad tables... >>>> >>>> pretty sure the issue was with schema disagreement. >>>> >>>> All our CREATE TABLE use IF NOT EXISTS.... but I think the IF NOT >>>> EXISTS only checks locally? >>>> >>>> My work around is going to be to use zookeeper to create a mutex lock >>>> during this operation. >>>> >>>> Any other things I should avoid? >>>> >>>> >>>> -- >>>> We’re hiring if you know of any awesome Java Devops or Linux Operations >>>> Engineers! >>>> >>>> Founder/CEO Spinn3r.com >>>> Location: *San Francisco, CA* >>>> blog: <http://burtonator.wordpress.com>http://burtonator.wordpress.com >>>> … or check out my Google+ profile >>>> <https://plus.google.com/102718274791889610666/posts> >>>> >>>> >> >> >> -- >> We’re hiring if you know of any awesome Java Devops or Linux Operations >> Engineers! >> >> Founder/CEO Spinn3r.com >> Location: *San Francisco, CA* >> blog: <http://burtonator.wordpress.com>http://burtonator.wordpress.com >> … or check out my Google+ profile >> <https://plus.google.com/102718274791889610666/posts> >> >> >> One way to accomplish both, a single process doing the work and having >> multiple machines be able to do it, is to have a control table. >> >> You can have a table that lists what tables have been created and force >> concistency all. In this table you list the names of tables created. If a >> table name is in there, it doesn't need to be created again. >> > -- *Ken Hancock *| System Architect, Advanced Advertising SeaChange International 50 Nagog Park Acton, Massachusetts 01720 ken.hanc...@schange.com | www.schange.com | NASDAQ:SEAC <http://www.schange.com/en-US/Company/InvestorRelations.aspx> Office: +1 (978) 889-3329 | [image: Google Talk:] ken.hanc...@schange.com | [image: Skype:]hancockks | [image: Yahoo IM:]hancockks [image: LinkedIn] <http://www.linkedin.com/in/kenhancock> [image: SeaChange International] <http://www.schange.com/> This e-mail and any attachments may contain information which is SeaChange International confidential. The information enclosed is intended only for the addressees herein and may not be copied or forwarded without permission from SeaChange International.
