I've looked at the archives of this mailing list to find a way to implement
a "multi-get" using Riak, for the very common case where there are multiple
keys to look up. Making a separate round-trip to the server for each key
seems inefficient, after all.
I came across the suggestion to use MapReduce, so I tried implementing it
this way (using riak-python-client):
def multi_get(self, bucket_name, ids):
if len(ids) == 0:
return []
mr = RiakMapReduce(self.riak)
for uid in ids:
mr.add(bucket_name, uid)
query = mr.map_values_json()
return query.run()
After this I noticed significant load on the Riak servers, and the client
code would sometimes stall for a long time, even on a multi_get that was
only returning 6 documents. Is this actually an inappropriate use of
MapReduce? (And are there appropriate uses of MapReduce in NoSQL databases
besides stress-testing them?)
Is it better to make a separate request for each ID, to use MapReduce, or
to use some other method I haven't thought of?
-- Rob
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