TiDB 2.0.4 Release Notes

On June 15, 2018, TiDB 2.0.4 is released. Compared with TiDB 2.0.3, this release has great improvement in system compatibility and stability.

TiDB

• Support the ALTER TABLE t DROP COLUMN a CASCADE syntax
• Support configuring the value of tidb_snapshot to TSO
• Refine the display of statement types in monitoring items
• Optimize the accuracy of query cost estimation
• Configure the backoff max delay parameter of gRPC
• Support configuring the memory threshold of a single statement in the configuration file
• Refactor the error of Optimizer
• Fix the side effects of the Cast Decimal data
• Fix the wrong result issue of the Merge Join operator in specific scenarios
• Fix the issue of converting the Null object to String
• Fix the issue of casting the JSON type of data to the JSON type
• Fix the issue that the result order is not consistent with MySQL in the condition of Union + OrderBy
• Fix the compliance rules issue when the Union statement checks the Limit/OrderBy clause
• Fix the compatibility issue of the Union All result
• Fix a bug in predicate pushdown
• Fix the compatibility issue of the Union statement with the For Update clause
• Fix the issue that the concat_ws function mistakenly truncates the result

PD

• Improve the behavior of the unset scheduling argument max-pending-peer-count by changing it to no limit for the maximum number of PendingPeers

TiKV

• Add the RocksDB PerfContext interface for debugging
• Remove the import-mode parameter
• Add the region-properties command for tikv-ctl
• Fix the issue that reverse-seek is slow when many RocksDB tombstones exist
• Fix the crash issue caused by do_sub
• Make GC record the log when GC encounters many versions of data