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Pre-GA Release Notes

On August 30, 2017, TiDB Pre-GA is released! This release is focused on MySQL compatibility, SQL optimization, stability, and performance.


  • The SQL query optimizer:
    • Adjust the cost model
    • Use index scan to handle the where clause with the compare expression which has different types on each side
    • Support the Greedy algorithm based Join Reorder
  • Many enhancements have been introduced to be more compatible with MySQL
  • Support Natural Join
  • Support the JSON type (Experimental), including the query, update and index of the JSON fields
  • Prune the useless data to reduce the consumption of the executor memory
  • Support configuring prioritization in the SQL statements and automatically set the prioritization for some of the statements according to the query type
  • Completed the expression refactor and the speed is increased by about 30%

Placement Driver (PD)

  • Support manually changing the leader of the PD cluster


  • Use dedicated Rocksdb instance to store Raft log
  • Use DeleteRange to speed up the deleting of replicas
  • Coprocessor now supports more pushdown operators
  • Improve the performance and stability

TiDB Connector for Spark Beta Release

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