2018-04-23-tidb-weekly.md

title	date	summary	tags
Weekly update (April 16 ~ April 22, 2018)	2018-04-23	Last week, we landed 36 PRs in the TiDB repositories, 8 PRs in the TiSpark repositories, and 29 PRs in the TiKV and PD repositories.	TiDB TiKV PD TiSpark

Weekly update in TiDB

Last week, we landed 36 PRs in the TiDB repositories.

Added

• Add TiDB HTTP API to query the DDL history information
• Add the session variable tidb_optimizer_selectivity_level to control the selectivity estimation level
• Add table partition information in SHOW CREATE TABLE
• Analyze the table automatically when the modified row count of a table is too large

Fixed

• Check if the column name already exists before renaming a column
• Fix a problem when parallel executing CREATE TABLE IF NOT EXISTS
• Fix pseudo selectivity estimation for the primary key
• Eliminate Projection when the schema length is 0
• Set the hash join concurrency in NewSessionVars

Improved

• Refactor scalarFuncToPBExpr
• Improve the cost estimation for physical aggregate operators
• Improve the execution performance of the UnionScanExec operator
• Cache global variables

Weekly update in TiSpark

Last week, we landed 8 PRs in the TiSpark repositories.

Fixed

• Fix the binary test and delete redundant issue tests
• Fix Protobuf definition according to TiKV changes

Weekly update in TiKV and PD

Last week, we landed 29 PRs in the TiKV and PD repositories.

Added

• Support specifying ColumnFamily in the rawkv APIs
• Add a new Region score function for balance that considers the free space of TiKV
• Support ScatterRegion

Fixed

• Fix the issue of reloading without persisted schedulers
• Fix wrongly collected Coprocessor statistics
• Bump the recursion limit to 200

Improved

• Upgrade the Rust and Clippy versions
• Add metrics to FuturePool
• Reduce the lock contention in WORKER