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TiDB RC3 Release Notes

On June 20, 2017, TiDB RC4 is released!This release is focused on MySQL compatibility, SQL optimization, stability, and performance.


  • The privilege management is refined to enable users to manage the data access privileges using the same way as in MySQL.
  • DDL is accelerated.
  • The load balancing policy and process are optimized for performance.
  • TiDB Ansible is open sourced. By using TiDB-Ansilbe, you can deploy, upgrade, start and shutdown a TiDB cluster with one click.

Detailed updates


  • The following features are added or improved in the SQL query optimizer:
    • Support incremental statistics
    • Support the Merge Sort Join operator
    • Support the Index Lookup Join operator
    • Support the Optimizer Hint Syntax
    • Optimize the memory consumption of the Scan, Join, Aggregation operators
    • Optimize the Cost Based Optimizer (CBO) framework
    • Refactor Expression
  • Support more complete privilege management
  • DDL acceleration
  • Support using HTTP API to get the data distribution information of tables
  • Support using system variables to control the query concurrency
  • Add more MySQL built-in functions
  • Support using system variables to automatically split a big transaction into smaller ones to commit

Placement Driver (PD)

  • Support gRPC
  • Provide the Disaster Recovery Toolkit
  • Use Garbage Collection to clear stale data automatically
  • Support more efficient data balance
  • Support hot Region scheduling to enable load balancing and speed up the data importing
  • Performance
    • Accelerate getting Client TSO
    • Improve the efficiency of Region Heartbeat processing
  • Improve the pd-ctl function
    • Update the Replica configuration dynamically
    • Get the Timestamp Oracle (TSO)
    • Use ID to get the Region information


  • Support gRPC
  • Support the Sorted String Table (SST) format snapshot to improve the load balancing speed of a cluster
  • Support using the Heap Profile to uncover memory leaks
  • Support Streaming SIMD Extensions (SSE) and speed up the CRC32 calculation
  • Accelerate transferring leader for faster load balancing
  • Use Batch Apply to reduce CPU usage and improve the write performance
  • Support parallel Prewrite to improve the transaction write speed
  • Optimize the scheduling of the coprocessor thread pool to reduce the impact of big queries on point get
  • The new Loader supports data importing at the table level, as well as splitting a big table into smaller logical blocks to import concurrently to improve the data importing speed.
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