RICON West 2012: Bringing Consistency to Riak (Part 2)

Joseph Blomstedt (@jtuple) Basho Technologies Bringing Consistency To Riak (Part
2) Tuesday, October 29, 13

CAP Theorem 2 Tuesday, October 29, 13

3 Partition-tolerance Consistency Availability Tuesday, October 29, 13

4 Partition-tolerance Consistency Availability Tuesday, October 29, 13

5 Partition-tolerance Consistency Availability CP AP Tuesday, October 29, 13

8 C/P Strict Quorum A/P Sloppy Quorum A/P Tuesday, October
29, 13

29, 13

10 Node 1 Node 2 Node 3 Node 4 Node
5 client client client Tuesday, October 29, 13

29, 13

5 client client client client client Tuesday, October 29, 13

Eventual Consistency 25 Tuesday, October 29, 13

26 A A A Tuesday, October 29, 13

28 A A A B Tuesday, October 29, 13

29 A A A B Tuesday, October 29, 13

30 A A A B B B B Tuesday, October
29, 13

32 A A A B C Tuesday, October 29, 13

33 A A A B C Tuesday, October 29, 13

34 A A A B {B,C} {B,C} {B,C} C Tuesday,
October 29, 13

35 Write Once Immutable Last Write Wins Business Rules CRDTs/Monotonicity
Tuesday, October 29, 13

Strong Consistency 41 Tuesday, October 29, 13

Strong Consistency 42 Why? Tuesday, October 29, 13

Strong Consistency 43 Recency Tuesday, October 29, 13

Strong Consistency 44 Recency Partial Writes Tuesday, October 29, 13

Strong Consistency 45 Recency Partial Writes Atomicity Tuesday, October 29,
13

46 Recency Partial Writes Atomicity Tuesday, October 29, 13

48 Eventual consistency is great Tuesday, October 29, 13

49 But, when is eventual? Tuesday, October 29, 13

50 Do I have the most recent value? Tuesday, October
29, 13

51 CRDTs don’t help Tuesday, October 29, 13

52 (a,1) (a,1) (a,1) =1 Tuesday, October 29, 13

53 (a,1) (a,1) (a,1) Tuesday, October 29, 13

54 (a,1) +1 +3 (a,1) (a,1) (a,2) (a,1),(b,3) =2 =4

55 (a,1) +1 +3 (a,1) (a,1) (a,2) (a,1),(b,3) Tuesday, October
29, 13

56 (a,1) +1 +3 (a,1) (a,1) (a,2) (a,1),(b,3) (a,2),(b,3) (a,2),(b,3)
(a,2),(b,3) Tuesday, October 29, 13

57 (a,1) +1 +3 (a,1) (a,1) (a,2) (a,1),(b,3) (a,2),(b,3) (a,2),(b,3)
(a,2),(b,3) =5 Tuesday, October 29, 13

58 (a,1) +1 +3 (a,1) (a,1) (a,2) (a,1),(b,3) =2 =4

60 A write B (fail) A A B A A

61 B A A Tuesday, October 29, 13

62 B A A read A read A read A

read B Tuesday, October 29, 13

Strong Consistency 66 Tuesday, October 29, 13

Strong Consistency 67 What does mean for Riak 2.0? Tuesday,
October 29, 13

68 Conditional single key atomic operations Tuesday, October 29, 13

69 No siblings Tuesday, October 29, 13

70 get sees most recent put Tuesday, October 29, 13

71 get/modify/put fails if object changed Tuesday, October 29, 13

72 get/modify/put fails if object changed (eg. concurrent put) Tuesday,
October 29, 13

73 puts w/o vclock fails if object exists Tuesday, October
29, 13

74 partial writes resolved on read Tuesday, October 29, 13

75 Consensus Tuesday, October 29, 13

76 Paxos Tuesday, October 29, 13

77 1RGH 1RGH
1RGH 1 SUHSDUH 1 SURPLVH 1 9 % SURPLVH 1 9 & 9 1 I 9 $ 9 % 9 & FRPPLW 1 9 1 DFFHSW 1 Tuesday, October 29, 13

78 Rinse/repeat for each request Tuesday, October 29, 13

79 2 round trips/request Tuesday, October 29, 13

80 Multi-Paxos Tuesday, October 29, 13

81 First Request Tuesday, October 29, 13

82 1RGH 1RGH
1RGH 1 , SUHSDUH 1 , SURPLVH 1 , 9 % SURPLVH 1 , 9 & 9 1 I 9 $ 9 % 9 & FRPPLW 1 , 9 1 DFFHSW 1 , Tuesday, October 29, 13

83 Each Additional Request Tuesday, October 29, 13

84 1RGH 1RGH
1RGH , FRPPLW 1 , 9 DFFHSW 1 , Tuesday, October 29, 13

85 1 round trip/request (common case) Tuesday, October 29, 13

86 Problem Shipping entire state each request is expensive Tuesday,
October 29, 13

87 Solution Paxos + Replicated Log Tuesday, October 29, 13

88 Problem Now I have N problems Tuesday, October 29,
13

89 Log recovery Log trimming Rollup Snapshots Fault Recovery Tuesday,
October 29, 13

90 Choose your own adventure... Tuesday, October 29, 13

91 Better Solution Build log replication into protocol Tuesday, October
29, 13

92 Better Solution ZK Atomic Broadcast Raft Tuesday, October 29,
13

Zab 93 Tuesday, October 29, 13

94 Tuesday, October 29, 13

Raft 98 Tuesday, October 29, 13

100 raftconsensus.github.io Tuesday, October 29, 13

101 Text Tuesday, October 29, 13

Back to Riak 102 Tuesday, October 29, 13

103 Key/Value Keys are independent Active Anti-Entropy Tunable backends Tuesday,
October 29, 13

104 Each key is independent state Tuesday, October 29, 13

105 Simple multi-paxos per key Tuesday, October 29, 13

106 1B keys = 1B consensus groups? Tuesday, October 29,
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107 No Tuesday, October 29, 13

108 Consensus group per preﬂist (replica set) Tuesday, October 29,
13

109 Emulate paxos per key Tuesday, October 29, 13

Node 0 Node 1 Node 2 Tuesday, October 29, 13

111 1 2 3 4 5 6 7 123 Tuesday,
October 29, 13

112 1 2 3 4 5 6 7 123 234

113 1 2 3 4 5 6 7 123 234

114 1 2 3 4 5 6 7 123 234
345 456 Tuesday, October 29, 13

115 1 2 3 4 5 6 7 123 234
345 456 567 ... Tuesday, October 29, 13

116 1 2 3 4 5 6 7 123 234
345 456 567 Ensembles ... Tuesday, October 29, 13

117 64 partition ring = 64 ensembles Tuesday, October 29,
13

118 Each Ensemble Elects leader Establishes epoch Supports get/put ops

119 Establish a new epoch Tuesday, October 29, 13

120 1RGH 1RGH
1RGH 1 , SUHSDUH 1 , SURPLVH 1 , 9 % SURPLVH 1 , 9 & 9 1 I 9 $ 9 % 9 & FRPPLW 1 , 9 1 DFFHSW 1 , Tuesday, October 29, 13

121 consensus state epoch sequence membership leader Tuesday, October 29,
13

122 K/V objects epoch sequence key value Tuesday, October 29,
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123 GET leader reads local object if obj.epoch old: refresh
reply w/ val Tuesday, October 29, 13

124 1RGH 1RGH
1RGH REMHSRFK HSRFK JHW .H\ UHSO\ (SRFK % 6HT % 9DO % UHSO\ (SRFK & 6HT & 9DO & 9DO ODWHVW 9DO $ 9DO % 9DO & 9DOHSRFK HSRFK ZULWH (SRFK 6HT 9DO DFN (SRFK 6HT Tuesday, October 29, 13

125 1RGH 1RGH
1RGH REMHSRFK HSRFK 5HSO\ ORFDOBJHW .H\ Tuesday, October 29, 13

126 2 roundtrips/get (worst) 0 roundtrip/get (best) Tuesday, October 29,
13

127 PUT leader reads local object if obj.epoch old: refresh
if modify(obj) false: fail commit modiﬁed obj reply ok Tuesday, October 29, 13

128 1RGH 1RGH
1RGH REMHSRFK HSRFK JHW .H\ UHSO\ (SRFK % 6HT % 9DO % UHSO\ (SRFK & 6HT & 9DO & /DWHVW ODWHVW 9DO $ 9DO % 9DO & 9DO PRGLI\ /DWHVW ZULWH (SRFK 6HT 9DO DFN (SRFK 6HT Tuesday, October 29, 13

129 1RGH 1RGH
1RGH REMHSRFK HSRFK /DWHVW ORFDOBJHW .H\ 9DO PRGLI\ /DWHVW ZULWH (SRFK 6HT 9DO DFN (SRFK 6HT Tuesday, October 29, 13

130 2 roundtrips/put (worst) 1 roundtrip/put (best) Tuesday, October 29,
13

131 Leader abandons leadership if any quorum operation ever fails

132 Which forces new epoch to be established Tuesday, October
29, 13

133 Partial Writes Tuesday, October 29, 13

failed partial write X (2) X (2) X (2) X
(2) X (2) Y (2) epoch 2 epoch 3 Tuesday, October 29, 13

read / rewrite / reply X X (2) X (2)
Y (2) X (3) X (3) Y (2) epoch 3 epoch 3 Tuesday, October 29, 13

X (3) X (3) Y (2) X (3) X (3)
X (3) read / repair / reply X epoch 3 epoch 3 Tuesday, October 29, 13

Usage 137 Tuesday, October 29, 13

138 AP or CP per bucket type Tuesday, October 29,
13

139 consistent = true Tuesday, October 29, 13

140 $ riak-admin bucket-type create strong \ '{"props": {"consistent": true}}'
strong created Tuesday, October 29, 13

141 $ riak-admin bucket-type activate strong strong has been activated

142 > riakc_pb_socket:get(Socket, {<<"strong">>, <<"bucket">>}, <<"key">>). {error,notfound} Tuesday, October 29,
13

143 > Obj = riakc_obj:new({<<"strong">>, <<"bucket">>}, <<"key">>, <<"1">>)). > riakc_pb_socket:put(Socket,
Obj). ok Tuesday, October 29, 13

144 > Obj2 = riakc_obj:new({<<"strong">>, <<"bucket">>}, <<"key">>, <<"2">>)). > riakc_pb_socket:put(Socket,
Obj2). {error, failed} Tuesday, October 29, 13

145 {ok, Obj3} = riakc_pb_socket:get(Socket, {<<"strong">>, <<"bucket">>}, <<"key">>). Tuesday, October
29, 13

146 Obj4 = riakc_obj:update_value(Obj3, <<"2">>). Tuesday, October 29, 13

147 Obj5 = riakc_obj:update_value(Obj3, <<"22">>). Tuesday, October 29, 13

148 > riakc_pb_socket:put(Socket, Obj4). ok Tuesday, October 29, 13

149 > riakc_pb_socket:put(Socket, Obj5). {error,<<"failed">>} Tuesday, October 29, 13

150 Your client may vary Tuesday, October 29, 13

151 Your client may vary We’re working on it Tuesday,
October 29, 13

Tech Preview 152 Tuesday, October 29, 13

153 No AAE syncing No 2i No stats Tuesday, October
29, 13

154 Will be in 2.0 ﬁnal Tuesday, October 29, 13

Coming Soon 155 Tuesday, October 29, 13

156 Datatypes Multi-DC Lightweight Tx? Perf benchmarks Tuesday, October 29,
13

13

Questions? 161 Tuesday, October 29, 13

RICON West 2012: Bringing Consistency to Riak (...

RICON West 2012: Bringing Consistency to Riak (Part 2)

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