TiDB強(qiáng)一致分布式數(shù)據(jù)庫(kù)介紹

1、技術(shù)創(chuàng)新，變革未來TiDB強(qiáng)一致分布式數(shù)據(jù)庫(kù)介紹錄What is TiDB?How to test?What is TiDB?Single PointSingle Point of FailureAsynchronous ReplicationA = 1B = 2A = 1MasterSlaveAsynchronous ReplicationA = 1B = 2A = 1 B = ?MasterSlaveSynchronous ReplicationA = 1B = 2A = 1B = 2MasterSlaveSynchronous ReplicationA = 1B = 2A = 1B =

2、2MasterSlaveServing?Slave - Master?Huge Amounts of DataMasterSlaveMasterSlaveMasterSlaveOpen-source NewSQL databaseHigh availabilityStrong consistencyHorizontal scalabilitySupport the MySQL wire protocol/pingcap/tidbTiDBOverviewMySQLwired protocolSQLNoSQLtidb-servertikv-serverNo single point of fail

3、ureAutomatic failoverHigh Availability at ScaleSnapshot isolation TiDBLinearizability TiKVStrong Consistency at ScaleRaftClientA = 1B = 2State MachineA = 1B = 2LogRaft ModuleA = 1B = 2State MachineA = 1B = 2LogRaft ModuleA = 1B = 2State MachineA = 1B = 2LogRaft ModuleLeader electionVoting for leader

4、Network isolation/node failure tiggers electionLog replicationLeader handles client requests, append logsReplicate logs to followersConstraintsQuorum: log replication, leader electionUp to date: leader electionRaft: Key PointsLazy PeerCross DC, cross regions deploymentLearnerCross DC, cross regions

5、backupJoint consensusSafe membership changingRaft: New FeaturesRaft: Lazy Peer3-DC in 2 regions deploymentRaft: LearnerFollowerFollowerLeaderLearnerReplace nodes?Node1Node2Node3Node2Node1Node3Node4Node1Node2Node4Raft: Joint consensusNode1Node2Node3Node1Node2Node4How to test?DistributedMultiple Compo

6、nentsStrong guarantee on weak foundation2-4% of disk drives fail each year N x 2-4%Broken optic cableIts complicated!Unit testsIntegration testsFuzz testinglibFuzzerAFLFault injectionFailpoint, https:/cgi/man.cgi?query=failJepsen, /jepsen-io/jepsenTestsA framework for distributed systems verificatio

7、n, with fault injectionFound bugsRedisetcdCassandraJepsenJepsen: How does it work?N1N2N3N4N5TiDB ClusterRequests &NemesisControlNetworkClockProcessNemesisNetwork: Partition OneN1N2N3N4N5Network: Partition RingN1N2N3N4N2N3N4N5N3N4N5N1N2N5N1Clock: Bump & Strobekill -9kill -SIGSTOPProcess: Kill & Pause

8、SI, the default isolation level for TiDBBank testCREATE TABLE accounts (id INT NOT NULL,balanceBIGINTNOT NULL);UPDATEaccountsSETbalance=balance-5WHEREid=1000;UPDATEaccountsSETbalance=balance+5WHEREid=2000;SI: Bank TestVerificationSELECT SUM(balance)FROMaccounts;SI: Bank TestSI: Bank TestWrite skew i

9、s valid in Snapshot IsolationSolution?SELECT FOR UPDATESI Write skew?Append unique numbers to key 0 and key 1Example:SELECTvalFROM tbWHERE id = 0;UPDATEtbSET val= 1,3,5,6,7 WHEREid =1;Write skew: Append TestWrite skew w/o read-lockT1:f :txn,:value:append 028:r 1 1 37 5611122 10817181915162223242521 28,:process 22T2:f :txn,:value:append 129:append 130:r 0 1 78 912131415161723192122182024274,:process 6Write skew w/o read-lockAppend unique numbers to key 0 and key 1Ex