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From Eric van Orsouw <eric.van.ors...@eventis.nl>
Subject iteration does not yield all data with consistency ONE
Date Wed, 10 Nov 2010 12:08:17 GMT
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.

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