Addendum: In the interest of completeness, it's worth noting that the Erlang builtins are here:
https://github.com/basho/riak_kv/blob/master/src/riak_kv_mapreduce.erl Mark On Sun, Sep 16, 2012 at 5:08 PM, Mark Phillips <[email protected]> wrote: > Hi Deepak, > > I can answer one of two questions here... > > On Fri, Sep 14, 2012 at 9:42 AM, Deepak Balasubramanyam > <[email protected]> wrote: >> Thanks for the tip Russell. I managed to get this done. >> >> I have one more question and a suggestion. >> >> Is the name keyData a misnomer in the mapping function -> function(value, >> keyData, arg) ? keyData is a String that carries the bucket name. The value >> object carries more information. value[0].data represents the data itself >> among other properties that represent user metadata; riak links; indexes; >> key; etc etc. >> If mapValuesJson: function(value, keyData, arg) can take an input argument >> and use it to add a json property whose value is the riak key, a custom >> function would not be necessary. It would be a neat little system feature >> which I take would need amendments to mapred_builtins.js. >> >> Is riak_kv the repo to make contributions to system built functions ? There >> are quite a few open pull requests on that repo, so I'm not sure where this >> change should go. >> > > The riak_kv repo is indeed the repo you want for this. Specifically, > you'll want to start here: > > https://github.com/basho/riak_kv/blob/master/priv/mapred_builtins.js > > As far as the large queue of pull requests go, we're working on > merging/addressing the backlog (for this and a few other repos). Send > yours our way. It'll get some love when time allows. > > Thanks. > > Mark > > >> >> Thanks >> Deepak Bala >> >> On Fri, Sep 14, 2012 at 7:16 PM, Russell Brown <[email protected]> wrote: >>> >>> >>> On 14 Sep 2012, at 14:24, Deepak Balasubramanyam wrote: >>> >>> > Hi, >>> > >>> > I've written a map reduce query on the riak java client like so... >>> > >>> > client.mapReduce(BUCKET).addKeyFilter(keyFilter) >>> > .addLinkPhase(BUCKET, "_", false) >>> > .addMapPhase(new >>> > NamedJSFunction("Riak.mapValuesJson"), false) >>> > .addReducePhase(phaseFunction).execute(); >>> > Collection<MyType> types = result.getResult(MyType.class); >>> > >>> > This is the class definition for MyType >>> > >>> > public class MyType >>> > { >>> > @RiakKey >>> > private String myKey; >>> > private String property1; >>> > private String property2; >>> > >>> > /* Getters / Setters go here */ >>> > } >>> > >>> > When the object mapper deserializes the results into Collection<MyType>, >>> > none of the types have the myKey property populated in them. When I >>> > debugged >>> > the calls made by riak I realized that the result of the /mapred call does >>> > not contain any key information in the body. It only contains the value >>> > that >>> > each key represents. So that explains why the keys are null in the result. >>> >>> The Java client doesn't add the value of the @RiakKey field to the value >>> stored in riak. >>> >>> > >>> > On the contrary, a link walk in riak returns the Location header for >>> > each multipart form entry in the response (Location: /riak/bucket/key). >>> > So I >>> > guess there is at least some way to tweak a client to parse the location >>> > to >>> > get the keys, but you lose out on the map-reduce goodness. >>> > >>> > Is there some way a map-reduce query can be formed to allow the >>> > resulting type's RiakKey to be populated ? What are my options ? >>> >>> A custom Map function may do what you want. Get the Key from the Key Data >>> passed to the Map function and add it to the JSON value returned. Jackson >>> should then take care of de-serialising it into your values. >>> >>> Cheers >>> >>> Russell >>> >>> > >>> > Thanks >>> > Deepak Bala >>> > _______________________________________________ >>> > riak-users mailing list >>> > [email protected] >>> > http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com >>> >> >> >> _______________________________________________ >> riak-users mailing list >> [email protected] >> http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com >> _______________________________________________ riak-users mailing list [email protected] http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com
