I have a similar requirement as that presented by the original poster, i.e
updating a totals count without having to push the entire data set through
the Mapper again.
Are you advising against calling incrementColumnValue on a mapper's HTable
instance because the operation is not idempotent or are there other
reasons? It is even suggested in the docs:
http://hbase.apache.org/book/mapreduce.example.html (section 7.2.6).
Do you know of any "count-exactly-once" implementations on top of Hadoop
On Tue, Jun 19, 2012 at 6:55 PM, Jean-Daniel Cryans <[EMAIL PROTECTED]>wrote:
> This question was answered here already:
> http://mail-archives.apache.org/mod_mbox/hbase-user/201101.mbox/%[EMAIL PROTECTED]%3E
> Counters are not idempotent, this can be hard to manage.
> On Mon, Jun 18, 2012 at 5:49 PM, Sid Kumar <[EMAIL PROTECTED]> wrote:
> > Hi everyone,
> > I have a use case in HBase that I was wondering if someone may have
> > stumbled upon. I am maintaining an ad impressions table with columns that
> > are counters for certain metrics. I started using the
> > method part of the HTable API to update these metrics and that works
> > I was wondering if this function could be used from a MapReduce job.
> > The TableOutputFormat supports only Delete and Put operations. Using the
> > Incremental counters saves me from doing any aggregations in my Map
> > code. Ideally i would like to just call this function in my mapper and
> > wouldn't even need a Reducer.
> > Has anyone run into this use case? I would also love to know if there
> > are any better alternatives of solving this too. Any info would be great.
> > Thanks
> > Sid