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TiDB RC4 Release Notes
/docs/dev/releases/release-rc.4/
/docs/dev/releases/rc4/
TiDB RC4 is released with a focus on MySQL compatibility, SQL optimization, stability, and performance. Highlights include improved write performance, better query cost estimating, and support for TiSpark to access data in TiKV. Detailed updates include refactoring of the SQL query optimizer, support for JSON type and operations, and optimization of the scheduler in Placement Driver. TiKV now supports RC isolation level, Document Store, and more pushdown functions in Coprocessor. TiSpark beta release includes prediction pushdown, aggregation pushdown, and range pruning, capable of running a full set of TPC-H queries.

TiDB RC4 Release Notes

On August 4, 2017, TiDB RC4 is released! This release is focused on MySQL compatibility, SQL optimization, stability, and performance.

Highlight

  • For performance, the write performance is improved significantly, and the computing task scheduling supports prioritizing to avoid the impact of OLAP on OLTP.
  • The optimizer is revised for a more accurate query cost estimating and for an automatic choice of the Join physical operator based on the cost.
  • Many enhancements have been introduced to be more compatible with MySQL.
  • TiSpark is now released to better support the OLAP business scenarios. You can now use Spark to access the data in TiKV.

Detailed updates

TiDB

  • The SQL query optimizer refactoring:
    • Better support for TopN queries
    • Support the automatic choice of the of the Join physical operator based on the cost
    • Improved Projection Elimination
  • The version check of schema is based on Table to avoid the impact of DDL on the ongoing transactions
  • Support BatchIndexJoin
  • Improve the Explain statement
  • Improve the Index Scan performance
  • Many enhancements have been introduced to be more compatible with MySQL
  • Support the JSON type and operations
  • Support the configuration of query prioritizing and isolation level

Placement Driver (PD)

  • Support using PD to set the TiKV location labels
  • Optimize the scheduler
    • PD is now supported to initialize the scheduling commands to TiKV.
    • Accelerate the response speed of the region heartbeat.
    • Optimize the balance algorithm
  • Optimize data loading to speed up failover

TiKV

  • Support the configuration of query prioritizing
  • Support the RC isolation level
  • Improve Jepsen test results and the stability
  • Support Document Store
  • Coprocessor now supports more pushdown functions
  • Improve the performance and stability

TiSpark Beta Release

  • Implement the prediction pushdown
  • Implement the aggregation pushdown
  • Implement range pruning
  • Capable of running full set of TPC-H except one query that needs view support