A Riak Query Tale - Speaker Deck

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A Riak Query Tale Mathias Meyer, @roidrage NoSQL Cologne

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http://riakhandbook.com

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Riak Distributed Database Fault-Tolerant Content-Agnostic Scalable on Demand

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Querying Data

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Key-Value $ curl localhost:8098/riak/users/roidrage

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Links $ curl -‐v localhost:8098/riak/users/roidrage < HTTP/1.1 200 OK < Link: ; riaktag="friend"

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Links $ curl .../riak/users/roidrage/users,friend,_/

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Listing Keys $ curl .../riak/users?keys=true

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Don’t do that!

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Streaming Keys $ curl .../riak/users?keys=stream

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Avoid that!

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Loads all the keys.

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MapReduce

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MapReduce Transform (Map) Aggregate (Reduce)

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Warning: JavaScript

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MapReduce riak.add("users"). map("Riak.mapValues"). run()

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MapReduce var nameLength = function(value) { var doc = Riak.mapValues(value)[0]; return [doc.length]; }

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MapReduce riak.add("users"). map(nameLength). run()

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MapReduce riak.add("users"). map(nameLength). reduce("Riak.reduceSum"). run()

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MapReduce var average = function(values) { var avg = values.reduce(function(n, sum) { return sum += n; }, 0); return [(avg / values.length)]; }

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MapReduce riak.add("users"). map(nameLength). reduce(average). run()

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MapReduce riak.add("users"). map(nameLength). reduce(average). run() Uh-Oh!

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MapReduce riak.add(["users", "roidrage"]). map(nameLength). reduce(average). run() Better!

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JavaScript M/R Breaks with Millions of Objects Uses External Libraries Serializes Data for JavaScript

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Warning: Erlang

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MapReduce riak.add('tweets'). map({language: 'erlang', module: 'riak_kv_mapreduce', function: 'map_object_value'}).run()

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MapReduce $ riak attach > {ok, C} = riak:local_client().

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MapReduce C:mapred([{<<"users">>, <<"roidrage">>}], [{map, {modfun, riak_kv_mapreduce, map_object_value}, none, false}, {reduce, {modfun, riak_kv_mapreduce, reduce_count_inputs}, none, true}]).

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MapReduce ExtractFirstName1 = fun(RObject, _, _) -‐> Value = riak_object:get_value(RObject), [FirstName, _] = re:split(Value, " "), [FirstName] end.

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MapReduce C:mapred([{<<"users">>, <<"roidrage">>}], [{map, {qfun, ExtractFirstName}, none, true}]).

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Erlang M/R Much more efficient than JavaScript No serialization No ad-hoc functions through HTTP

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Key-Filters Reduce MapReduce input Based on key matches

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Key-Filters riak.add({bucket: 'users', key_filters: [["matches", "^roid"]]})

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Key-Filters riak.add({bucket: 'users', key_filters: [["to_upper"], ["matches", "^ROID"]]})

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Key-Filters riak.add({bucket: 'users', key_filters: [["to_upper"], ["to_lower"], ["matches", "^roid"]]})

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Key-Filters riak.add({bucket: 'users', key_filters: [["to_upper"], ["ends_with", "RAGE"]]})

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Key-Filters riak.add({bucket: 'users', key_filters: [["and", [["string_to_int"], ["less_than", 10]], [["string_to_int"], ["greater_than", 5]]]]})

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Don't use key filters.

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Riak 2i Sorted Secondary Indexes Simple Reverse Lookups Maintained Manually Requires LevelDB

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Riak 2i curl -‐X PUT .../riak/users/roidrage -‐d @-‐ \ -‐H "Content-‐Type: text/plain" \ -‐H "X-‐Riak-‐Index-‐firstname_bin: mathias" \ -‐H "X-‐Riak-‐Index-‐lastname_bin: meyer"

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Riak 2i X-‐Riak-‐Index-‐firstname_bin: Mathias X-‐Riak-‐Index-‐lastname_bin: Meyer

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Riak 2i X-‐Riak-‐Index-‐firstname_bin: Mathias X-‐Riak-‐Index-‐lastname_bin: Meyer X-‐Riak-‐Index-‐age_int: 34

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Riak 2i X-‐Riak-‐Index-‐firstname_bin: Mathias X-‐Riak-‐Index-‐lastname_bin: Meyer X-‐Riak-‐Index-‐age_int: 34 X-‐Riak-‐Index-‐topics_bin: nosql,cloud,operations

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Riak 2i # Match $ curl .../buckets/users/index/firstname_bin/Mathias

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Riak 2i # Range $ curl .../buckets/users/index/firstname_bin/Mathias/Till

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Riak 2i # Key $ curl .../buckets/users/index/$key/roidrage

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Ordered Keys! (sort of)

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MapReduce riak.add({bucket: 'users', index: 'lastname_bin', key: 'mathias'}). map('Riak.mapValuesJson').run()

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Riak 2i No Multi-Index Queries Requires Extra Work in the App Returns only keys Document-partitioned

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Riak Search Full-Text Search Solr-ish Interface Integrates with Riak

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Riak Search curl -‐X PUT localhost:8098/riak/users -‐d @-‐ \ -‐H "Content-‐Type: application/json" {"props":{"precommit": [{"mod":"riak_search_kv_hook","fun":"precommit"} ]}}

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Indexing Riak Objects curl -‐X PUT .../riak/users/roidrage \ -‐d "Mathias Meyer" -‐H "Content-‐Type: text/plain"

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Solr-ish Interface curl .../solr/users/select?q=value:Mathias

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Riak Search value:Mathias OR value:Till value:Mathias AND value:Meyer value:Mat* value:[Mathias TO Till]

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MapReduce riak.addSearch("users", "value:Mathias"). map("Riak.mapValues").run()

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Riak Search Full text search of structured data Term-partitioned Efficient for one term queries Multiple Interfaces No Anti-Entropy