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From Eric van Orsouw <eric.van.ors...@eventis.nl>
Subject RE: iteration does not yield all data with consistency ONE
Date Wed, 10 Nov 2010 14:58:37 GMT
No, all nodes were up and running while the single key was inserted.
The insert however was with consistency One. I assume however that the replicas are still
written in this case.
It is btw also very reproducible.

-----Original Message-----
From: Jonathan Ellis [mailto:jbellis@gmail.com] 
Sent: woensdag 10 november 2010 15:44
To: user
Subject: Re: iteration does not yield all data with consistency ONE

Was the node that should have the other replica of this row down when
it was inserted?

On Wed, Nov 10, 2010 at 6:08 AM, Eric van Orsouw
<eric.van.orsouw@eventis.nl> wrote:
>
> Hello,
>
>
>
> We have a cluster of 4 nodes (0.6.6) and use the random partitioner and a replication
of 2.
>
> When I insert a number of rows I can always retrieve them by their explicit id (get_range_slices("<key>","",
1).
>
> Playing with consistency levels and temporarily shutting down a Cassandra node all yields
the expected result.
>
>
>
> However when I use get_range_slices("","", n) to iterate over all rows, I sometimes don't
get anything (depending on the node).
>
>
>
> I then reduced the problem to inserting just a single row.
>
> Specifically, the 'iteration' only seems to succeed when I issue the request to the node
that contains the first copy.
>
> I Discovered that when I iterate using a consistency level of Quorum/All the iteration
always succeeds and I properly get the one row.
>
>
>
> So a solution would be to always use consistency level One/All but that has a performance
penalty.
>
>
>
> Can anyone explain why iterating using get_range_slices("","",n) does not always function
with consistency level One on all nodes?
>
>
>
> Thanks,
>
> Eric
>
>
>
> P.S. To rule out any discussion on whether or not to use iteration in the first place,
we only plan to use it for backup and periodic cleanup cycles.


--
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of Riptano, the source for professional Cassandra support
http://riptano.com

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