pd-server v2.1.0

• Optimize availability

  • Introduce the version control mechanism and support rolling update of the cluster compatibly
  • Enable Raft PreVote among PD nodes to avoid leader reelection when network recovers after network isolation
  • Enable raft learner by default to lower the risk of unavailable data caused by machine failure during scheduling
  • TSO allocation is no longer affected by the system clock going backwards
  • Support the Region merge feature to reduce the overhead brought by metadata

• Optimize the scheduler

  • Optimize the processing of Down Store to speed up making up replicas
  • Optimize the hotspot scheduler to improve its adaptability when traffic statistics information jitters
  • Optimize the start of Coordinator to reduce the unnecessary scheduling caused by restarting PD
  • Optimize the issue that Balance Scheduler schedules small Regions frequently
  • Optimize Region merge to consider the number of rows within the Region
  • Add more commands to control the scheduling policy
  • Improve PD simulator to simulate the scheduling scenarios

• API and operation tools

  • Add the GetPrevRegion interface to support the TiDB reverse scan feature
  • Add the BatchSplitRegion interface to speed up TiKV Region splitting
  • Add the GCSafePoint interface to support distributed GC in TiDB
  • Add the GetAllStores interface, to support distributed GC in TiDB
  • pd-ctl supports:
    • using statistics for Region split
    • calling jq to format the JSON output
    • checking the Region information of the specified store
    • checking topN Region list sorted by versions
    • checking topN Region list sorted by size
    • more precise TSO encoding
  • pd-recover doesn't need to provide the max-replica parameter

• Metrics

  • Add related metrics for Filter
  • Add metrics about etcd Raft state machine

• Performance

  • Optimize the performance of Region heartbeat to reduce the memory overhead brought by heartbeats
  • Optimize the Region tree performance
  • Optimize the performance of computing hotspot statistics