A map reduce job is a batch request. It takes in a list of {Bucket,Key}
pairs and returns the result. Though writing map reduce in the erlang PB
client is not exactly as nice as one would think. This is the function I
use:
% P = riak connection
% B = bucket
% LI = list of keys
mget_bin(P,B,LI) ->
case riakc_pb_socket:mapred(P,[{B,key(Key)} || Key <- LI],
[{reduce, {modfun, riak_kv_mapreduce, reduce_set_union}, none, false},
{map, {modfun, riak_kv_mapreduce, map_identity}, none, true}]) of
{ok,[{_,L}|_]} ->
{ok,[Val ||
{r_object,_Bucket,_Key,[{r_content,_Meta,Val}],_VClock,_UpdateMeta,_UpdateVal}
<- L]};
{error,notfound} ->
undefined;
X ->
X
end.
On Sat, Jul 28, 2012 at 6:26 PM, Parnell Springmeyer <ixma...@gmail.com>wrote:
> Hi everyone!
>
> I figured out what my bottleneck was - HTTP API + sequential (as opposed
> to concurrent) GET requests.
>
> I wrote a simple Erlange Cowboy handler that uses a worker pool OTP
> application I built to make concurrent GETs using the PBC api. My Python
> web app makes a call to the handler and it simulates "batched" requests.
>
> It would be a great feature in Riak to have batched GETs built in…it
> shouldn't be too difficult to add to the PBC or HTTP API's and it would be
> enormously useful, particularly in the event where the client KNOWS the key
> space and wants a batch of results.
>
> I might make an experimental fork of Riak to add that feature if Basho
> isn't working on something similar?
>
>
> _______________________________________________
> riak-users mailing list
> riak-users@lists.basho.com
> http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com
>
>
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