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带RIAK的MapReduce

riak mapreduce erlang

3

yazz.com · 技术社区 · 15 年前

是否有任何人具有可以在单个RIAK节点上运行的用于RIAK的MapReduce示例代码?

2 回复 | 直到 15 年前

1

5

Zed 15 年前

cd ~/riak
erl -name zed@127.0.0.1 -setcookie riak -pa apps/riak/ebin

壳牌:

# connect to the server
> {ok, Client} = riak:client_connect('riak@127.0.0.1').
{ok,{riak_client,'riak@127.0.0.1',<<6,201,208,64>>}}

# create and insert objects
> Client:put(riak_object:new(<<"groceries">>, <<"mine">>, ["eggs", "bacons"]), 1).
ok
> Client:put(riak_object:new(<<"groceries">>, <<"yours">>, ["eggs", "sausages"]), 1).
ok

# create Map and Reduce functions
> Count = fun(G, 'undefined', 'none') ->
            [dict:from_list([{I, 1} || I <- riak_object:get_value(G)])]
          end.
#Fun<erl_eval.18.105910772>
> Merge = fun(Gcounts, 'none') ->
            [lists:foldl(fun(G, Acc) ->
                           dict:merge(fun(_, X, Y) -> X+Y end, G, Acc)
                         end, dict:new(), Gcounts)] 
          end.
#Fun<erl_eval.12.113037538>

# do the map-reduce
> {ok, [R]} = Client:mapred([{<<"groceries">>, <<"mine">>},
                             {<<"groceries">>, <<"yours">>}],
                            [{'map', {'qfun', Count}, 'none', false},
                             {'reduce', {'qfun', Merge}, 'none', true}]).           
{ok,[{dict,...

> dict:to_list(R).
[{"eggs",2},{"susages",1},{"bacons",1}]

对于服务器,我使用了绝对默认的配置:

$ hg clone http://hg.basho.com/riak/
$ cd riak
$ ./rebar compile generate
$ cd rel
$ ./riak/bin/riak start

2

Augustus 15 年前

这里有一个 example 如何使用javascript函数执行mapreduce。