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From Jeremy Hanna <>
Subject Re: Migrating all rows from 0.6.13 to 0.7.5 over thrift?
Date Fri, 06 May 2011 22:35:19 GMT
If you're able, go into the #cassandra channel on freenode (IRC) and talk to driftx or jbellis
or aaron_morton about your problem.  It could be that you don't have to do all of this based
on a conversation there.

On May 6, 2011, at 5:04 AM, Henrik Schröder wrote:

> I'll see if I can make some example broken files this weekend.
> /Henrik Schröder
> On Fri, May 6, 2011 at 02:10, aaron morton <> wrote:
> The difficulty is the different thrift clients between 0.6 and 0.7.
> If you want to roll your own solution I would consider:
> - write an app to talk to 0.6 and pull out the data using keys from the other system
(so you know can check referential integrity while you are at it). Dump the data to flat file.
> - write an app to talk to 0.7 to load the data back in.
> I've not given up digging on your migration problem, having to manually dump and reload
if you've done nothing wrong is not the best solution. I'll try to find some time this weekend
to test with:
> - 0.6 server, random paritioner, standard CF's, byte column
> - load with python or the cli on osx or ubuntu (dont have a window machine any more)
> - migrate and see whats going on.
> If you can spare some sample data to load please send it over in the user group or my
email address.
> Cheers
> -----------------
> Aaron Morton
> Freelance Cassandra Developer
> @aaronmorton
> On 6 May 2011, at 05:52, Henrik Schröder wrote:
> > We can't do a straight upgrade from 0.6.13 to 0.7.5 because we have rows stored
that have unicode keys, and Cassandra 0.7.5 thinks those rows in the sstables are corrupt,
and it seems impossible to clean it up without losing data.
> >
> > However, we can still read all rows perfectly via thrift so we are now looking at
building a simple tool that will copy all rows from our 0.6.3 cluster to a parallell 0.7.5
cluster. Our question is now how to do that and ensure that we actually get all rows migrated?
It's a pretty small cluster, 3 machines, a single keyspace, a singke columnfamily, ~2 million
rows, a few GB of data, and a replication factor of 3.
> >
> > So what's the best way? Call get_range_slices and move through the entire token
space? We also have all row keys in a secondary system, would it be better to use that and
make calls to get_multi or get_multi_slices instead? Are we correct in assuming that if we
use the consistencylevel ALL we'll get all rows?
> >
> >
> > /Henrik Schröder

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