申砾 -TiDB一种混合OLTP和OLAP数据库

ShenLi@ShenLi@PingCAPAboutme•TechLeadofTiDB,VPofNetease/PingCAP•InfrastructuresoftwareengineerWHYDOWENEEDANEW•StandaloneRDBMS•NoSQL••StandaloneRDBMS•NoSQL•Middleware&Proxy•NewSQLNoSQLNewSQLMySQLPostgreSQLOracleDB2...RedisHBaseCassandraMongoDB...RDBMSRDBMSPPresent1970s20152010GGoogleSpannerGoogleF1TiDB•HorizontalScalability•ACIDTransaction•HighAvailability•Auto-Failover•SQLs•Complexquerylogic•Transaction&IsolationlevelHOWDOWEBUILDANEWSQL•Scalabilityasthefirstclassfeature•SQLisnecessary•CompatiblewithMySQL,inmostcases•OLTP+OLAP=HTAP(HybridTransactional/AnalyticalProcessing)•24/7availability,evenincaseofdatacenteroutages•Opensource,ofcourseTiDBTiDBTiKVTiKVTiKVTiDBTiDBTiKVTiKVTiKVDistributedStorageLayerStatelessSQLLayerTiDTiDBgRPCTTiKVRaftRaftRaftRaftMetadata/TimestamprequestPlacemegRPCntDriver(PD)gRPCBalance/FailovergRPCBalance/Failover•HashBasedPartitionoBadforscan•RangeBasedPartitionenoughAPITransactionTiKVMVCCRaft(gRPC)APITransactionTiKVMVCCRaft(gRPC)enchraw/main.go)•TiKVistheunderlyingstoragel•Physically,dataisstoredinRoc•WebuildaRaftlayerontopofoWhatisRaft?•WritteninRust!(gRPC)KV(gRPC)KVAPI/pingcap/tidb/blob/(https:///pingcap/tidb/blob/API(https://github.cokv/API(https://github.cokv/main.go)RocksDBob/master/cmd/b(gRPC)TransactionMVCCRaftRocksDBf-j]RocksDBInstance(gRPC)TransactionMVCCRaftRocksDBf-j]RocksDBInstanceRocksDBInstancef-j]RocksDBInstance···Raftgroup•DataisorganizedbyRegions•Region:asetofcontinuouskey-valuepairsf-jf-j]Instance•What’sDynamicMulti-Raft?oDynamicsplit/merge•Safesplit/mergesplit splitsplitRRegionRRegionRegionTiKV1RegionTiKV3RegionTiKV1RegionTiKV3raftraftRaftRaftgroupRegRegionTiKV2erererRegionTiKV3RegionTiKV2ionRegionTiKV3RegionTiKV2iontionV1ererTiKRegerTiKV1RegionTiKVTiKV1RegionTiKV3RegionTiKV2plitlogreplicatedbyRafterererRegionacRegiond-e]TiKV1RegionacRegiond-e]TiKV1RegionacRegiond-e]TiKV3raftraftraftraftRegionRegionacRegiond-e]TiKV2erererNodeRegion1Region2RegionNodeRegion1Region2RegionRegionRegion1*Region2 RegionNodeARegRegion13Region 3NodeCNodeDRegion1Region3Region1*Region2Region3NodeAScale-out(addnewnode)Region1Region3Region1*Region2Region3NodeA•AddanewnodeERegion1Region1^Region2RegionRegion2Region3NodeCfromNodeAtoNodeBNodeCfromNodeAtoNodeBNodeD1NodeRegion1*Region2Region2Region3Region1NodeRegion1*Region2Region2Region3Region1RegionRegion1Region2Region3NodeAERegionRegion1Region3NodeNode2)NodeNodeAddReplica2)NodeENodeDNodeRegion1*Region2Region2RegionNodeRegion1*Region2Region2Region3Region1RegionRegion2Region3NodeAENodeRegionRegion1Region3NodeNodeRemoveReplicafromRemoveReplicafromANodeD•BasedonGooglePercolator•‘Almost’decentralized2-phasecommit•Optimistictransactionmodel•Defaultisolationlevel:RepeatableRead•Externalconsistency:SnapshotIsolation+Lock•Full-featuredSQLlayer•Predicatepushdown•Cost-basedoptimizer•ParallelOperators•MultipleJoinOperators•Hash/StreamingOperatorsCREATETABLEt(c1INT,c2TEXT,KEYidx_c1(c1));SELECTCOUNT(c1)FROMtWHEREc1>10ANDc2=‘golang’;PhysicalPlanTiDBPhysicalPlanTiKV(indexscan)PartialAggregateCOUNT(c1)RowCOUNT(c1)FPhysicalPlanTiDBPhysicalPlanTiKV(indexscan)PartialAggregateCOUNT(c1)RowCOUNT(c1)Filterc2=“golang”RowReadRowDatayRowIDCOUNT(c1)COUNT(c1)RowIDTiKVReadIndexidx1:(10,+∞)TiKVTiKVCOUNT(c1)bFinalAggregateDistSQLScanSUM(COUNT(c1))Scheduler•Priority•JobSizeScheduler•Priority•JobSizeJobJobJobQueueSQLISNOTENOUGHSparkMasterSparkExecSparkExec SparkExec TiKVConnectorTiKVConnector TiKVConnectorTiKVSparkMasterSparkExecSparkExec SparkExec TiKVConnectorTiKVConnector TiKVConnectorTiKVTiKVTiKVTiKVTiKVTTiDBTiDBTiDBStorageStorage&CoprocessorTiSpark2/3•TiKVConnectorisbetterthanJDBCconnector•ComplexCalculationPushdown•CBO–PickuprightAccessPath–JoinReorderTiSpark3/3•Analytical/Transactionalsupportallonone–NoneedforETL–Real-timequeryw