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POLARDB: A database architecture for the cloud
- 1. POLARDB: A database architecturefor the cloud
- 2. ØYSTEIN GRØVLEN Sr. StaffEngineer @ Alibaba Cloud Bio: Before joining Alibaba, Øystein worked for 10 years in the MySQL optimizer team at Sun/Oracle. At Sun Microsystems, he was also a contributor on the Apache Derby project and Sun's Architectural Lead on Java DB. Prior to that, he worked for 10 years on development of Clustra, a highly available DBMS.
- 3. POLARDB：a Cloud NativeDatabase Emerging Hardware • NVM • RDMA • FPGA Serverless • Auto Scaling • Paid by Usage • Zero Downtime Security • Encryption • Audit • Access Control Intelligence • Self-configuration • Self-optimization • Self-diagnosis • Self-healing CLOUD NATIVE User Oriented
- 4. Database Architecture Revolution: Separation of Storage and Computation Transaction Architecture: Separation of Storage and Computation Database Storage Engine Computation OffloadingStorage Compatibility SecurityHTAPMulti-Model Usability Self-Driving Manageability
- 5. Cloud Native Architecture •Scale compute and storage independently • Shared storage • Across AZ fail-over without data loss • Optimize division of functionality between storage and compute • Tight integration with other cloud components like metering, monitoring, control plan • Optimize for hardware in the data centers • Compatible with MySQL/PG etc • Security PolarProxy PolarStore POLARDB Intelligent proxy 100% Compatible Storage Optimized For Database PolarFS
- 6. PolarStore: Architecture overview -Design for Emerging Hardware - Low Latency Oriented - Active R/W – Active RO - High Availability libpfs Host1 POLARDB libpfs POLARDB Host2 volume 1 Volume 2 chunk1 chunk2 chunk1 chunk2 PolarSwitch libpfs POLARDB volume 1 PolarSwitch chunk1 chunk2 ChunkServer ChunkServer ChunkServer ChunkServer chunk chunk chunk chunk ParallelRaft PolarCtrl metadata Key Components: 1. libpfs 2. PolarSwitch 3. ChunksServer 4. PolarCtrl data route control route
- 7. PolarStore: Design forEmerging Hardware - No Context Switch - OS-bypass & zero-copy RDMA-NIC Network Over RDMA libpfs POLARDB Memory - Parallel Random I/O absorbed by Optane - Excellent performance with less long tail latency issue - No need of Over Provisioning WAL Log in 3Dxpoint optane RDMA Network RDMA RDMA-NIC Optane NVMe SSDs Memory Chunkserver 1 RDMA-NIC Optane NVMe SSDs Memory Chunkserver 3 RDMA-NIC Optane NVMe SSDs Memory Chunkserver 2 PolarDB write to shm
- 8. PolarFS: posix distributedfile system closely with DB Pure User Space For Extra-low Latency - No Sys call - No Context Switch - Zero Data Copy Posix Semantics - Easy Porting Node 1 libpfs POLARDB Journal file Paxos file Low Latency Oriented libpfs POLARDB libpfs POLARDB Node 2 Node 3 1 2 3 4 5 6 head pending tail tail POLARDB Cluster File System Metadata Cache Directory Tree File Mapping Table root FileBlk VolBlk 0 1 2 … 348 1500 0 201 … 6 Database Volume Chunks … Block Mapping Table FileID FileBlk 489 478 … 16 0 201 … VolBlk 200 201 202 0 2010 316 … 3 PolarFS: An Ultra-low Latency and Failure Resilient Distributed File System for Shared Storage Cloud Database （VLDB 2018）
- 9. Dynamic Scaling Local Storage Fast Scaling MySQL POLARDB Master Local Storage Replica Local Storage Replica MasterReplica Replica Shared Storage Upgrade 2vCPU to 32vCPU， only in 5 minutes Add more Replicas, only in 5 minutes. 数值轴 1 Replica 2 Replica 3 Replica 4 Replica 5 Replica 10 Replica 20,949 11,349 9,749 8,149 6,549 4,949 39,844 20,102 16,811 13,521 10,230 6,940 RDS MySQL POLARDB Lower Cost: 30%~50% OFF Total costs of 4vCPU 32G Memory 500G Storage with different replica numbers 0 10000 20000 30000 40000
- 10. Shared Nothing LogicalReplication vs. Shared Storage Physical Replication Local Storage Local Storage Master POLARSTORE Slave Master Slave Data Binlog Redo log Data Master Binlog Slave Binlog Redo log Data Redo log Data Redo log Binlog Physical Replication is much more reliable than Logical Replication
- 11. Shared Nothing LogicalReplication vs. Shared Storage Physical Replication Non-blocking low-latency DDL synchronization Master Slave Timeline Add Column Running 1 Hour Add Column Blocked 1 Hour Applying DDL will block following events Add Column Update data files Update metadata Need not modify data files MySQL POLARDB Shared Storage Master Slave
- 12. Physical Replication byRedo Log Commit Async Flush Data File Redo Log DATA LOG & MEMORY Primary Shared Storage Log Parse Hash Table Redo Buffer Pool Buffer Pool Write Memory Query Snapshot of T4 T2 T4 T5 T1 T3 T3T2T1 T4 T5 T3T2T1 T4 T3T2T1 T4 T5 RO Node T4 Transactions Buffer Pool Shared Storage Continuous Recovery Consistent Snapshot Read T1
- 13. Physical Replication -Page from Past Oldest read view Control purge Avoid Data Gap Checkpoint LSN (T1) Primary Shared Storage Log Parse Hash Table Redo Buffer Pool Snapshot of T4 T2 T4 T5 T1 T3 T3T2T1 T4 T5 T3T2T1 T4 T1 T4Buffer Pool Data Redo Log Checkpoint T1 T3T2T1 T4 Purgeable Unpurgeable RO Node Primary RO Node
- 14. Physical Replication -Page from Future Avoid Data Overstep Control flush datafile Primary Shared Storage Log Parse Hash Table Redo Buffer Pool Snapshot of T4 T2 T4 T5 T1 T3 T3T2T1 T4 T5 T3T2T1 T4 T1 T4Buffer Pool Data Redo Log Snapshot Version T4 Unflushable T5 T3T2T1 T4 Flushable T4T3T2Primary Snapshot Version T4 LSN of the latest applied redolog RO Node RO Node
- 15. Single Master Single EndpointTransparent Failover Attacks Protection Causal Consist Read Proxy Cluster Master Replica Replica Shared Storage Application Replica Read/Write Split High Availability Load Balance Security
- 16. Read and WriteSeparation - Session Consistent Problem Can’t read latest data Solved! connection.query { UPDATE user SET name=‘Jimmy’ WHERE id=1; COMMIT; SELECT name FROM user WHERE id=1; // name is Jimmy } SELECT can always get the latest data POLARDB Cluster LSN 30 LSN 35 1. UPDATE 2. SELECT Log Serial Number LSN 35 1. UPDATE 3. SELECT Require LSN>=35) 2. Return LSN=35 M R1 R2 Application Smart Proxy Read & Write Separation Load Balance Module
- 17. Multi-master Storage Monitoring Segment Servers DB ServersDB ServersDB Servers AZ1 AZ2 AZ3 segment 1 Segment Servers Segment Servers CS1 CS2 CS3 CS4 CS5 CS6 Database Cluster (Compute) Storage Service 3-AZ Persistent Core (append-only) TCPTCP Storage Cluster Page read RDMA RDMA RDMA redo segment 1 segment 1
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