Transaction Support over Redis: An Overview

0.45 MB·

by  Yuqing Zhu

Transaction Support over Redis: An Overview
YuqingZhu,JianxunLiu,MengyingGuo,WenlongMa, YungangBao
Instituteof ComputingTechnology,ChineseAcademyofSciences
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This document serves as an overview for describing we propose to implement concurrency control through
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how to support cross-node transactions over a Redis consensus reduction [3]; or, if the read-committed
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cluster. isolationlevelisallowed,wecansimplyadoptthewrite-
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Redis is a key-value in-memory store. It supports on-commit mechanism. To guarantee high availability,

] the common interface for data access. Besides, it many replica control methods [2, 5] can be employed
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supportsthetransaction-likeinterfacesofMGET/MSET while the master-slave replication of Redis is also a
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and MULTI/EXEC locally on a Redis node. The feasible choice given an optimistic assumption on the
s. two transaction-like interfaces enable useful and handy deployment. The consistency property is generally
c implementationsofapplications. Butunfortunatelythey specified through legal rules. We leave the support of
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arenotsupportedintheclustermodeofRedis. legalrule specificationsand consistencychoicesfor the

1 futureversionofACIAtransactionsystems.
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0 Figure2:Thearchitectureforthecross-nodetransaction
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: With the above implementation choices, the overall
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system architecture is depicted in Figure 2. The
i Figure1:Asix-nodeRediscluster.
X communication protocol between transaction managers
r The cluster mode of Redis guarantees scalability are the atomic commit protocol HACommit. The
a through data partition and high availability through the storageengineistheRedissystem.Thecommunications
master-slave replication. A typical minimum Redis betweenstorageenginesfollowthepatternimplemented
cluster setup is to have a three Master Redis nodes by the cluster-mode Redis. In our architecture, the
with each master node replicated with a single Redis storage engine is one guaranteeing high availability, as
slave instance node, as illustrated in Figure 1. The demonstrated in Figure 3. Replication is an inevitable
keys stored in a Redis cluster are typically partitioned componentinthehighly-availablestorageengine,while
into orthogonal segments, each of which is stored giventhe master-slavereplicationof Redis, HACommit
by a Mater node. To support the transaction-like isthefastestatomiccommitprotocoltochoose.
accessesonarbitrarykeys,cross-nodetransactionsmust
besupportedoveraRedisCluster.
As high availability is widely demanded by online
applications,wethereforeproposetoimplementtransac-
tionswith ACIA (Atomicity,Consistency, Isolationand
Availability)properties[1]inthecurrentRedisdistribu-
tion. To guarantee atomicity, we adopt the HACommit
Figure 3: The typical architecture of a highly-available
atomic commit protocol [4]. To guarantee isolation,
storageengine.
Notethatthehighly-availablestorageenginecanalso Researchof China(GrantNo. 2014CB340402)andthe
bereplacedbythedurablestorageenginein Figure4if National Natural Science Foundation of China (Grant
needed. In implementations, we need only to remove No. 61303054).
thecommunicationswithreplicasandassumethewrite-
ahead logging in the critical path of writes involved in References
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[4] ZHU, Y., YU, P. S., BAO, Y., YI, G., MA, W., GUO, M.,
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Acknowledgments This work is supported in part
by the State Key Development Program for Basic 1https://sites.google.com/site/zhuyuqing/acia
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