Thinking about a migration, practically speaking this would be doable:

- Flush and compact everything.  Get rid of reference files from region
splits.
- Take each mapfile (ignore the index files), read the file in, write an
equivalent hfile out.
- Done!

This can't be done while the cluster is online however.

Any other suggestions?

On Thu, Apr 2, 2009 at 12:09 AM, stack <[email protected]> wrote:

> I made HBASE-1215 as issue to cover migration from 0.19.x to 0.20.0.
>
> We have a migration 'system' already.  You run ./bin/hbase migrate. Going
> from 0.19.0 to 0.20.0, we'll need to add a mapreduce job that rewrites all
> hbase data to new format.  It needs to be MR for those cases where data is
> large.
>
> I thought at first that we could do lazy migration but after looking at it,
> keeping up two key types in the one context looked too complex.
>
> St.Ack
>
> On Thu, Apr 2, 2009 at 8:51 AM, Ryan Rawson <[email protected]> wrote:
>
> > hi all,
> >
> > it's been a long road, but it's time to start thinking about what will
> > conclusively be in 0.20.
> >
> > I'll let you fight that out a bit... personally I'd be happy with hfile +
> > KeyValue.
> >
> > But, one last thing, what is our migration story going to be?
> >
> > -ryan
> >
>

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