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 >>> … 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 > … 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. >
