are Siblings ordered?

Russell Brown russell.brown at mac.com
Tue Oct 8 03:24:31 EDT 2013


I'd very much like to see the same thing.

I have a working branch and test here https://github.com/basho/riak_kv/pull/688 and https://github.com/basho/riak_test/tree/feature/rdb-sib-ex

This isn't using the DVVSets but a sort of rough hack, where we store the event dot for each write in the metadata dictionary for that value. As you can see from the test it works. There is some work to be done to productionise it, I really hope I get time for that. Feel free to pitch in (the riak_object tests that are broken would be the first place to help.)

My only concern is with client id vclocks (which are still supported in Riak.)

Cheers

Russell

On 8 Oct 2013, at 05:40, Pedram Nimreezi <mc at majorcomputing.com> wrote:

> I'd like to see the dotted version vectors get launched, even with merging siblings high concurrency = high amount of unnecessary siblings,
> Which wastes space and impacts performance. Dotted version vectors helps improve this. Proof of concept and paper available...
> 
> On Oct 7, 2013 3:06 PM, "Sam Elliott" <sam.elliott at basho.com> wrote:
> Each sibling has it's own last-modified date, which you should be able to use to sort them when you get them back.
> 
> However, I'd suggest the following: if they're siblings, they were created from concurrent edits. Thus, create a merge function that is entirely deterministic without using the timestamp. This should save you from any clock skew issues, and also from the fact that an edit may not have been performed with the most up-to-date information.
> 
> I guess people can't wait for our CRDTs to launch.
> 
> Sam
> 
> --
> Sam Elliott
> Engineer
> sam.elliott at basho.com
> --
> 
> 
> On Monday, 7 October 2013 at 2:47PM, Alex Rice wrote:
> 
> > Yes, exactly that's what I'm working on. By knowing which sibling is
> > the oldest and which is the newest it seems like I can usually figure
> > out how to marge/apply the modifications. Things like Player profiles,
> > friends lists, etc.
> >
> > On Mon, Oct 7, 2013 at 12:43 PM, Jeremiah Peschka
> > <jeremiah.peschka at gmail.com (mailto:jeremiah.peschka at gmail.com)> wrote:
> > > There's no guarantee of return order as far as I know. Since you can't count
> > > on clocks anyway...
> > >
> > > Are you trying to determine which data modifications to apply from multiple
> > > siblings?
> > >
> > > ---
> > > sent from a tiny portion of the hive mind...
> > > in this case, a phone
> > >
> > > On Oct 7, 2013 11:40 AM, "Alex Rice" <alex at mindlube.com (mailto:alex at mindlube.com)> wrote:
> > > >
> > > > Are they ordered by timestamp, and is the ordering guaranteed? (within
> > > > the clock accuracy of course). Using the C# client Thanks,
> > > > Alex
> > > >
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