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Pre-GA release notes

/docs/dev/releases/release-pre-ga/

/docs/dev/releases/prega/

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