Weekly update in TiDB

Last week, we landed 30 PRs in the TiDB repositories.

Added

• Refactor the optimizer:
  • Refactor ranger/statistic: calculate the range and row count of non pk column.
• JSON type:
  • Support generated column:](https://github.com/pingcap/tidb/pull/3431)
  • Support the JSON type in the cast expression.
• Generated column:
  • Support basic generated column.
  • Prevent modifying generated column.
  • Add GeneratedExpr in ColumnInfo.
• Support using clause in join statement.
• Use GetTSAsync api from pd-client.
• Support SubTime.

Fixed

• Fix a bug in alter table statement.
• Fix a bug in cast.
• Fix a bug about parsing Duration literal.
• Fix a divide zero bug in statistic.
• Fix a protobuf unmarshal related bug in coprocessor.
• Fix a bug about auto_increment column conflict after renaming table.

Improved

• Add some columns in mysql.user: compatiable with MySQL.
• Use multiple grpc connnections for each store: improve performance.
• Refactor expression evaluation:
  • Consider unsigned flag in cast expression.
• Speed up DDL process:
  • Revoke the etcd-session when ddl worker is closed.

Weekly update in TiKV

Last week, We landed 14 PRs in the TiKV repositories.

Added

• Coprocessor supports index scan executor.
• Add MySQL JSON type.
• Support comparison for mySQL JSON type.

Fixed

• Fix a bug caused by GC with stale command.

Improved

• Increase initialized window size to 2MB for gRPC stream.
• Using prefix_same_as_start to optimize seek for Write CF.
• Use multiple connections to speed up Raft message sending.
• Update Dockerfile, see 1915 and 1919.

New contributor

• AkihiroSuda