tidb v3.0.0-rc.2 Release Notes

Release Date: 2019-05-28 // almost 5 years ago
  • โšก๏ธ SQL Optimizer

    • ๐Ÿ‘Œ Support Index Join in more scenarios #10540
    • ๐Ÿ‘Œ Support exporting historical statistics #10291
    • ๐Ÿ‘Œ Support the incremental Analyze operation on monotonically increasing index columns #10355
    • Neglect the NULL value in the Order By clause #10488
    • ๐Ÿ›  Fix the wrong schema information calculation of the UnionAll logical operator when simplifying the column information #10384
    • Avoid modifying the original expression when pushing down the Not operator #10363
    • ๐Ÿ‘Œ Support the dump/load correlation of histograms #10573 ### Execution Engine
    • ๐Ÿ– Handle virtual columns with a unique index properly when fetching duplicate rows in batchChecker #10370
    • ๐Ÿ›  Fix the scanning range calculation issue for the CHAR column #10124
    • ๐Ÿ›  Fix the issue of PointGet incorrectly processing negative numbers #10113
    • ๐Ÿ”€ Merge Window functions with the same name to improve execution efficiency #9866
    • ๐Ÿ‘ Allow the RANGE frame in a Window function to contain no OrderBy clause #10496

    Server

    ๐Ÿ›  Fix the issue that TiDB continuously creates a new connection to TiKV when a fault occurs in TiKV #10301 Make tidb_disable_txn_auto_retry affect all retryable errors instead of only write conflict errors #10339 ๐Ÿ‘ Allow DDL statements without parameters to be executed using prepare/execute #10144 Add the tidb_back_off_weight variable to control the backoff time #10266 Prohibit TiDB retrying non-automatically committed transactions in default conditions by setting the default value of tidb_disable_txn_auto_retry to on #10266 ๐Ÿ›  Fix the database privilege judgment of role in RBAC #10261 ๐Ÿ‘Œ Support the pessimistic transaction model (experimental) #10297 ๐Ÿ”’ Reduce the wait time for handling lock conflicts in some cases #10006 ๐Ÿ‘‰ Make the Region cache able to visit follower nodes when a fault occurs in the leader node #10256 Add the tidb_low_resolution_tso variable to control the number of TSOs obtained in batches and reduce the times of transactions obtaining TSO to adapt for scenarios where data consistency is not so strictly required #10428

    DDL

    ๐Ÿ›  Fix the uppercase issue of the charset name in the storage of the old version of TiDB #10272 ๐Ÿ‘Œ Support preSplit of table partition, which pre-allocates table Regions when creating a table to avoid write hotspots after the table is created #10221 ๐Ÿ›  Fix the issue that TiDB incorrectly updates the version information in PD in some cases #10324 ๐Ÿ‘Œ Support modifying the charset and collation using the ALTER DATABASE statement #10393 ๐Ÿ‘Œ Support splitting Regions based on the index and range of the specified table to relieve hotspot issues #10203 Prohibit modifying the precision of the decimal column using the alter table statement #10433 ๐Ÿ›  Fix the restriction for expressions and functions in hash partition #10273 ๐Ÿ›  Fix the issue that adding indexes in a table that contains partitions will in some cases cause TiDB panic #10475 Validate table information before executing the DDL to avoid invalid table schemas #10464 0๏ธโƒฃ Enable hash partition by default; and enable range columns partition when there is only one column in the partition definition #9936