TiDB 3.1.1 Release Notes

Release date: April 30, 2020

TiDB version: 3.1.1

TiDB Ansible version: 3.1.1

New Features

TiDB
- Add the table option for auto_rand_base #16812
- Add the Feature ID comment: In the special comments of SQL statements, only the registered statement fragment can be parsed by the parser; otherwise, the statement is ignored #16155
TiFlash
- Cache the handle and version columns to reduce the disk I/O for a single read request
- Add in Grafana the graphics related to the read and write workloads of DeltaTree engine
- Optimize the decimal data encoding in the Chunk codec
- Reduce the number of open file descriptors when TiFlash is in low workload

TiDB
- Fix the issue that the isolation read setting at the instance level does not take effect, and that the isolation read setting is incorrectly retained after TiDB is upgraded #16482 #16802
- Fix the partition selection syntax on the hash partitioned table so that an error is not reported for syntaxes such as partition (P0) #16076
- Fix the issue that when an UPDATE SQL statement only queries from a view but does not update the view, the update statement still reports an error #16789
- Fix the issue of wrong results caused by removing the not not from the nested query #16423
TiFlash
- Fix the issue that an error occurs when reading data from a Region that is in the abnormal state
- Modify the mapping of table names in TiFlash to correctly support recover table/flashback table
- Modify the storage path to fix the potential data loss issue that occurs when renaming a table
- Modify the read mode in the online update scenario to improve the read performance
- Fix the issue that TiFlash fails to start normally after upgrade if the database/table name contains special characters
Tools
- Backup & Restore (BR)
  - Fix the issue that after BR restores a table with the auto_random attribute, inserting data might trigger the duplicate entry error #241