Hi fxmy,
> The return value is just Bucket/Key/link-tag pairs, without ObjectValue or
> other metadata.
> {ok,[{0,[[<<"people">>,<<"timoreilly">>,<<"friend">>]]},
> {1,[[<<"people">>,<<"dhh">>,<<"friend">>]]}]}
>
> Is this intended or not?
This is intended. You are running a map reduce job with one “link” stage,
which does the link walking for you.
Link stages only return a list of key/value/relation tuples.
> If so, what's the best way to get these ObjectValues through one single pass
> of link-walking?
If you want to grab everything in one shot you would have to feed the link
stage’s output into a map stage to grab the actual objects:
{ok, RiakObj} = riakc_pb_socket:mapred(Pid,[{<<"people">>, <<"timoreilly">>}],
[{link, <<"people">>, <<"friend">>, false},
{link, <<"people">>, <<"friend">>, false},
{map, {modfun, riak_kv_mapreduce, map_identity}, none, true}]).
This should give you the entire object for the results of the last link phase,
namely Dave Thomas’s.
I should warn you thought that while link walking and map reduce let you do
things like this in one shot, you should be cautious about using them in
production since a bad query can kill performance.
Thanks,
Alex
On Mar 14, 2014, at 6:49 AM, fxmy wang <fxm...@gmail.com> wrote:
>
> Hi, list,
>
> This should be a trivial question and I think I'm definitely missing
> something( and feeling stupid :\).
>
> So when I am doing a chained link-walking through HTTP interface like
> this(copied from link walking docs):
> curl -v localhost:8091/riak/people/davethomas/_,friend,1/_,friend,_/
>
> The output is quite verbose, including Bucket/Key/Value etc.etc.
> --JCgqdOHsL4BdXPCb0cuQDnLTxOH
> Content-Type: multipart/mixed; boundary=LpfqXc9urbAJJNFH7aGGPBiAtnX
>
> --LpfqXc9urbAJJNFH7aGGPBiAtnX
> X-Riak-Vclock: a85hYGBgzGDKBVIcc+04TgWFOj/NYEpkzGNlyNCadoYvCwA=
> Location: /riak/people/timoreilly
> Content-Type: text/plain
> Link: </riak/people/dhh>; riaktag="friend", </riak/people>; rel="up"
> Etag: 3DmGNeyDj2hUlLR2UhJvMr
> Last-Modified: Thu, 13 Mar 2014 13:11:04 GMT
>
> I am an excellent public speaker.
> --LpfqXc9urbAJJNFH7aGGPBiAtnX--
>
> --JCgqdOHsL4BdXPCb0cuQDnLTxOH
> Content-Type: multipart/mixed; boundary=IcBLyeIFObvJlJGyXuhTty5cRSs
>
> --IcBLyeIFObvJlJGyXuhTty5cRSs
> X-Riak-Vclock: a85hYGBgzGDKBVIcR4M2cgeFOkdkMCUy5rEyzNSadoYvCwA=
> Location: /riak/people/dhh
> Content-Type: text/plain
> Link: </riak/people>; rel="up"
> Etag: 4qbA2ZufXNgzFRb8PlSLUO
> Last-Modified: Thu, 13 Mar 2014 13:11:53 GMT
>
> I drive a Zonda.
> --IcBLyeIFObvJlJGyXuhTty5cRSs--
>
> --JCgqdOHsL4BdXPCb0cuQDnLTxOH--
>
>
> But when I retried it through the erlang_pb_client
> riakc_pb_socket:mapred(Pid,[{<<"people">>, <<"davethomas">>}],[{link,
> <<"people">>, <<"friend">>, true},{link, <<"people">>, <<"friend">>, true}]).
>
> The return value is just Bucket/Key/link-tag pairs, without ObjectValue or
> other metadata.
> {ok,[{0,[[<<"people">>,<<"timoreilly">>,<<"friend">>]]},
> {1,[[<<"people">>,<<"dhh">>,<<"friend">>]]}]}
>
> Is this intended or not?
> If so, what's the best way to get these ObjectValues through one single pass
> of link-walking?
>
>
> Cheers,
> _______________________________________________
> riak-users mailing list
> riak-users@lists.basho.com
> http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com
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