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.

TiDB

• 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

TiKV

• 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