riak mapreduce with limit on response size in java

Vote count:

0

I'm trying to run a mapReduce query on Riak 1.4 that queries by secondary index, sorts the records by date, and then limits the results to the first record.

I've got the secondary index query working. The sort doesn't seem to do anything. No errors on the sort, just returns the results unsorted. The limit on the number of records returned yields a 'bad_json' error returned by the server.

Here's what I have. It is suppose to query the "cars" bucket for the most recent car owned by "john_doe". (some names have been changed to protect the innocent;) :

JSSourceFunction dateSortFunction = new JSSourceFunction(
    "function(v) {" +
        "return v.sort(function(a, b) {" +
            "return a.issueDate - b.issueDate ;" +
        "}" +
    ");" +
"}");

IndexQuery iq = new BinValueQuery(BinIndex.named("person"), "cars", "john_doe");

MapReduceResult response = session.mapReduce(iq)
   .addMapPhase(NamedErlangFunction.MAP_OBJECT_VALUE)
   .addReducePhase(dateSortFunction)
   .addReducePhase(new NamedJSFunction("Riak.reduceLimit"), 1)
   .execute();

I've seen a number of posts on sorting and am hoping to figure it out eventually. However, I haven't seen any help on how the LIMIT function might work.

Thanks in advance!

asked 1 min ago

user3179263

6