Hi Kevin Have you looked at Cassandra's lightweight transactions? It sounds like they might work for you http://www.datastax.com/documentation/cassandra/2.0/cassandra/dml/dml_ltwt_transaction_c.html.
-- Daniel > On 17/11/2014, at 1:51 pm, Kevin Burton <bur...@spinn3r.com> wrote: > > I’m trying to have some code acquire a lock by first at performing a table > mutation, and then if it wins, performing a second table insert. > > I don’t think this is possible with batches though. > > I don’t think I can say “update this table, and if you are able to set the > value, and the value doesn’t already exist, then insert into this other table” > > I can do this in Java code, but it’s not transactional. Which is fine of > course, I can work around some code to make it safe. > > My plan B is to perform a conditional update by doing an IF NOT EXISTS and if > I win then I can do the insert but only for a limited time while I hold the > lock. > > But I don’t know if even this is possible without a write then read because > the datastax driver doesn’t allow me to read the values that were written. > I’d have to do another SELECT to read them back out. > > -- > Founder/CEO Spinn3r.com > Location: San Francisco, CA > blog: http://burtonator.wordpress.com > … or check out my Google+ profile >
