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From Whitney Sorenson <wsoren...@hubspot.com>
Subject Re: ZooKeeper transaction properties (partial read)
Date Fri, 05 Feb 2016 21:35:14 GMT
I filed:

https://issues.apache.org/jira/browse/ZOOKEEPER-2362

On Tue, Feb 2, 2016 at 10:18 PM, Alexander Shraer <shralex@gmail.com> wrote:

> Hi,
>
> I think this situation shouldn't happen - the result of step 3 implies that
> the multi happened, so 4 should see it (multi should be atomic). Could you
> please open a high priority bug for this ?
>
> Thanks,
> Alex
>
> On Mon, Feb 1, 2016 at 2:40 PM, Whitney Sorenson <wsorenson@hubspot.com>
> wrote:
>
> > 1. Starting state : { /foo = <does not exist>, /bar = <does not exist>
}
> > 2. In a multi, write: { /foo = A, /bar = B}
> > 3. Read /foo as A
> > 4. Read /bar as <does not exist>
> >
> > #3 and #4 are issued 100% sequentially.
> >
> > It is not known at what point during #2, #3 starts.
> >
> > - Whitney
> >
> >
> > On Mon, Feb 1, 2016 at 5:08 PM, Jared Cantwell <jared.cantwell@gmail.com
> >
> > wrote:
> >
> > > Am I understanding you correctly that you are observing the following?
> > >
> > >    1. Starting state {/foo = A , /bar = B}
> > >    2. In a multi, write {/foo->A', /bar = B'}
> > >    3. Read /foo as A'
> > >    4. Read /bar as B
> > >
> > > #3 & #4 start after #2 completes entirely, right?  And #3 & #4 are
> issued
> > > 100% sequentially?
> > >
> > > ~Jared
> > >
> > > On Mon, Feb 1, 2016 at 2:54 PM, Alexander Shraer <shralex@gmail.com>
> > > wrote:
> > >
> > > > Reading the 965 JIRA what you're describing sounds like a bug.
> > > >
> > > > Alex
> > > >
> > > > On Mon, Feb 1, 2016 at 10:41 AM, Whitney Sorenson <
> > wsorenson@hubspot.com
> > > >
> > > > wrote:
> > > >
> > > > > Hi,
> > > > >
> > > > > In searching through the ZK documentation, this list,
> > > > > https://issues.apache.org/jira/browse/ZOOKEEPER-965, and curator
> > > > > documentation (which we're using to talk to ZK) I can't find
> anything
> > > > > definitive explaining the guarantees around using transactions.
> > > > >
> > > > > I am now beginning to wonder if I wrongly assumed that partial
> reads
> > > were
> > > > > not possible during transactions, because I have now observed this
> > > > behavior
> > > > > twice.
> > > > >
> > > > > I'd just like to confirm that this is the expected behavior:
> > > > >
> > > > > ZK 3.4.6
> > > > > Curator 2.8.0
> > > > >
> > > > > I write 2 nodes in a transaction, however, I am able to see one of
> > the
> > > > > nodes without seeing the other in 2 subsequent reads.
> > > > >
> > > > > Eventually, I am able to see both nodes. When I am talking about
> > seeing
> > > > the
> > > > > nodes I am talking about reads from the same client which issued
> the
> > > > > transaction talking to the same ZK server.
> > > > >
> > > > > - Whitney
> > > > >
> > > >
> > >
> >
>

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