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From Jeremy Hanna <jeremy.hanna1...@gmail.com>
Subject Re: cassandra + pig
Date Thu, 11 Oct 2012 17:03:32 GMT
For our use case, we had a lot of narrow column families and the couple of column families
that had wide rows, we did our own paging through them.  I don't recall if we did paging in
pig or mapreduce but you should be able to do that in both since pig allows you to specify
the slice start.

On Oct 11, 2012, at 11:28 AM, William Oberman <oberman@civicscience.com> wrote:

> If you don't mind me asking, how are you handling the fact that pre-widerow you are only
getting a static number of columns per key (default 1024)?  Or am I not understanding the
"limit" concept?  
> 
> On Thu, Oct 11, 2012 at 11:25 AM, Jeremy Hanna <jeremy.hanna1234@gmail.com> wrote:
> The Dachis Group (where I just came from, now at DataStax) uses pig with cassandra for
a lot of things.  However, we weren't using the widerow implementation yet since wide row
support is new to 1.1.x and we were on 0.7, then 0.8, then 1.0.x.
> 
> I think since it's new to 1.1's hadoop support, it sounds like there are some rough edges
like you say.  But issues that are reproducible on tickets for any problems are much appreciated
and they will get addressed.
> 
> On Oct 11, 2012, at 10:43 AM, William Oberman <oberman@civicscience.com> wrote:
> 
> > I'm wondering how many people are using cassandra + pig out there?  I recently went
through the effort of validating things at a much higher level than I previously did(*), and
found a few issues:
> > https://issues.apache.org/jira/browse/CASSANDRA-4748
> > https://issues.apache.org/jira/browse/CASSANDRA-4749
> > https://issues.apache.org/jira/browse/CASSANDRA-4789
> >
> > In general, it seems like the widerow implementation still has rough edges.  I'm
concerned I'm not understanding why other people aren't using the feature, and thus finding
these problems.  Is everyone else just setting a high static limit?  E.g.  LOAD 'cassandra://KEYSPACE/CF?limit=X"
where X >= the max size of any key?  Is everyone else using data models that result in
keys with # columns always less than 1024?  Do newer version of hadoop consume the cassandra
API in a way that work around these issues?  I'm using CDH3 == hadoop 0.20.2, pig 0.8.1.
> >
> > (*) I took a random subsample of 50,000 keys of my production data (approx 1M total
key/value pairs, some keys having only a single value and some having 1000's).  I then wrote
both a pig script and simple procedural version of the pig script.  Then I compared the results.
 Obviously I started with differences, though after locally patching my code to fix the above
3 bugs (though, really only two issues), I now (finally) get the same results.
> 
> 
> 


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