Seems reasonable. If you want the earliest duplicate message to win instead of the latest one, you can store a processed flag in the database instead of storing a nonce, but otherwise it sounds fine.
On Mon, Nov 3, 2014 at 10:46 AM, Kevin Burton <bur...@spinn3r.com> wrote: > I have a database with activemq where I use AMQ to execute items in the > database. > > The problem is how do I keep AMQ and my DB in sync so that there’s only > once entry in AMQ for a given database entry. > > So I think this is a simple solution to that problem and wanted feedback. > > Each logical unit of work is given a work-id which is a nonce. > > So if you have a “foo” table in your db record, it would have a work-id. > > When you enqueue it you give the message a work id. > > The consumer of the AMQ message reads the work ID for the message, and > reads the db table, and if they aren’t identical, it just acks the message, > and returns, doing nothing. > > This way the appropriate AMQ message, which is scheduled later, will > process the message only once. > > This means: > > - if your DB and AMQ become out of sync you can just repair the AMQ > instance from the DB by doing a table scan of your DB and re-enqueueing > everything. > > - if you accidentally request something to be processed twice, the earlier > message will be discarded and only the later one will win. > > I think this is a simple/elegant way of solving this problem. > > thoughts? > > -- > > 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> > <http://spinn3r.com> >
