TiDB 2.0 RC5 Release Notes

On April 17, 2018, TiDB 2.0 RC5 is released. This release has great improvement in MySQL compatibility, SQL optimization and stability.

TiDB

Fix the issue about applying the Top-N pushdown rule
Fix the estimation of the number of rows for the columns that contain NULL values
Fix the zero value of the Binary type
Fix the BatchGet issue within a transaction
Clean up the written data while rolling back the Add Index operation, to reduce consumed space
Optimize the insert on duplicate key update statement to improve the performance by 10 times
Fix the issue about the type of the results returned by the UNIX_TIMESTAMP function
Fix the issue that the NULL value is inserted while adding NOT NULL columns
Support showing memory usage of the executing statements in the Show Process List statement
Fix the issue that Alter Table Modify Column reports an error in extreme conditions
Support setting the table comment using the Alter statement

Support the Region specified by compact in tikv-ctl
Support Batch Put, Batch Get, Batch Delete and Batch Scan in the RawKVClient
Fix the OOM issue caused by too many snapshots
Return more detailed error information in Coprocessor
Support dynamically modifying the block-cache-size in TiKV through tikv-ctl
Further improve importer
Simplify the ImportSST::Upload interface
Configure the keepalive property of gRPC
Split tikv-importer from TiKV as an independent binary
Provide statistics about the number of rows scanned by each scan range in Coprocessor
Fix the compilation issue on the macOS system
Fix the issue of misusing a RocksDB metric
Support the overflow as warning option in Coprocessor