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release-rc.4.md

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TiDB RC4 Release Notes
/docs/dev/releases/release-rc.4/
/docs/dev/releases/rc4/

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