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