tidb v3.0.0-rc.2 Release Notes
Release Date: 2019-05-28 // almost 5 years ago-
โก๏ธ SQL Optimizer
- ๐ Support Index Join in more scenarios #10540
- ๐ Support exporting historical statistics #10291
- ๐ Support the incremental
Analyze
operation on monotonically increasing index columns #10355 - Neglect the NULL value in the
Order By
clause #10488 - ๐ 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 - ๐ Support the
dump
/load
correlation of histograms #10573 ### Execution Engine - ๐ Handle virtual columns with a unique index properly when fetching duplicate rows in
batchChecker
#10370 - ๐ Fix the scanning range calculation issue for the
CHAR
column #10124 - ๐ Fix the issue of
PointGet
incorrectly processing negative numbers #10113 - ๐ Merge
Window
functions with the same name to improve execution efficiency #9866 - ๐ Allow the
RANGE
frame in aWindow
function to contain noOrderBy
clause #10496
Server
๐ 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 ๐ Allow DDL statements without parameters to be executed usingprepare
/execute
#10144 Add thetidb_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 oftidb_disable_txn_auto_retry
toon
#10266 ๐ Fix the database privilege judgment ofrole
inRBAC
#10261 ๐ Support the pessimistic transaction model (experimental) #10297 ๐ Reduce the wait time for handling lock conflicts in some cases #10006 ๐ Make the Region cache able to visit follower nodes when a fault occurs in the leader node #10256 Add thetidb_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 #10428DDL
๐ Fix the uppercase issue of the charset name in the storage of the old version of TiDB #10272 ๐ Support
preSplit
of table partition, which pre-allocates table Regions when creating a table to avoid write hotspots after the table is created #10221 ๐ Fix the issue that TiDB incorrectly updates the version information in PD in some cases #10324 ๐ Support modifying the charset and collation using theALTER DATABASE
statement #10393 ๐ 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 thealter table
statement #10433 ๐ Fix the restriction for expressions and functions in hash partition #10273 ๐ 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๏ธโฃ Enable hash partition by default; and enable range columns partition when there is only one column in the partition definition #9936