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TiDB 2.1 RC1 Release Notes
On August 24, 2018, TiDB 2.1 RC1 is released! Compared with TiDB 2.1 Beta, this release has great improvement in stability, SQL optimizer, statistics information, and execution engine.
TiDB
- SQL Optimizer
- Fix the issue that a wrong result is returned after the correlated subquery is decorrelated in some cases #6972
- Optimize the output result of
Explain
#7011#7041 - Optimize the choosing strategy of the outer table for
IndexJoin
#7019 - Remove the Plan Cache of the non-
PREPARE
statement #7040 - Fix the issue that the
INSERT
statement is not parsed and executed correctly in some cases #7068 - Fix the issue that the
IndexJoin
result is not correct in some cases #7150 - Fix the issue that the
NULL
value cannot be found using the unique index in some cases #7163 - Fix the range computing issue of the prefix index in UTF-8 #7194
- Fix the issue that result is not correct caused by eliminating the
Project
operator in some cases #7257 - Fix the issue that
USE INDEX(PRIMARY)
cannot be used when the primary key is an integer #7316 - Fix the issue that the index range cannot be computed using the correlated column in some cases #7357
- SQL Execution Engine
- Fix the issue that the daylight saving time is not computed correctly in some cases #6823
- Refactor the aggregation function framework to improve the execution efficiency of the
Stream
andHash
aggregation operators #6852 - Fix the issue that the
Hash
aggregation operator cannot exit normally in some cases #6982 - Fix the issue that
BIT_AND
/BIT_OR
/BIT_XOR
does not handle the non-integer data correctly #6994 - Optimize the execution speed of the
REPLACE INTO
statement and increase the performance nearly 10 times #7027 - Optimize the memory usage of time type data and decrease the memory usage of the time type data by fifty percent #7043
- Fix the issue that the returned result is mixed with signed and unsigned integers in the
UNION
statement is not compatible with MySQL #7112 - Fix the panic issue caused by the too much memory applied by
LPAD
/RPAD
/TO_BASE64
/FROM_BASE64
/REPEAT
#7171 #7266 #7409 #7431 - Fix the incorrect result when
MergeJoin
/IndexJoin
handles theNULL
value #7255 - Fix the incorrect result of
Outer Join
in some cases #7288 - Improve the error message of
Data Truncated
to facilitate locating the wrong data and the corresponding field in the table #7401 - Fix the incorrect result for
decimal
in some cases #7001 #7113 #7202 #7208 - Optimize the point select performance #6937
- Prohibit the isolation level of
Read Committed
to avoid the underlying problem #7211 - Fix the incorrect result of
LTRIM
/RTRIM
/TRIM
in some cases #7291 - Fix the issue that the
MaxOneRow
operator cannot guarantee that the returned result does not exceed one row #7375 - Divide the Coprocessor requests with too many ranges #7454
- Statistics
- Optimize the mechanism of statistics dynamic collection #6796
- Fix the issue that
Auto Analyze
does not work when data is updated frequently #7022 - Decrease the Write conflicts during the statistics dynamic update process #7124
- Optimize the cost estimation when the statistics is incorrect #7175
- Optimize the
AccessPath
cost estimation strategy #7233
- Server
- Fix the bug in loading privilege information #6976
- Fix the issue that the
Kill
command is too strict with privilege check #6954 - Fix the issue of removing some binary numeric types #6922
- Shorten the output log #7029
- Handle the
mismatchClusterID
issue #7053 - Add the
advertise-address
configuration item #7078 - Add the
GrpcKeepAlive
option #7100 - Add the connection or
Token
time monitor #7110 - Optimize the data decoding performance #7149
- Add the
PROCESSLIST
table inINFORMMATION_SCHEMA
#7236 - Fix the order issue when multiple rules are hit in verifying the privilege #7211
- Change some default values of encoding related system variables to UTF-8 #7198
- Make the slow query log show more detailed information #7302
- Support registering tidb-server related information in PD and obtaining this information by HTTP API #7082
- Compatibility
- Support Session variables
warning_count
anderror_count
#6945 - Add
Scope
check when reading the system variables #6958 - Support the
MAX_EXECUTION_TIME
syntax #7012 - Support more statements of the
SET
syntax #7020 - Add validity check when setting system variables #7117
- Add the verification of the number of
PlaceHolder
s in thePrepare
statement #7162 - Support
set character_set_results = null
#7353 - Support the
flush status
syntax #7369 - Fix the column size of
SET
andENUM
types ininformation_schema
#7347 - Support the
NATIONAL CHARACTER
syntax of statements for creating a table #7378 - Support the
CHARACTER SET
syntax in theLOAD DATA
statement #7391 - Fix the column information of the
SET
andENUM
types #7417 - Support the
IDENTIFIED WITH
syntax in theCREATE USER
statement #7402 - Fix the precision losing issue during
TIMESTAMP
computing process #7418 - Support the validity verification of more
SYSTEM
variables #7196 - Fix the incorrect result when the
CHAR_LENGTH
function computes the binary string #7410 - Fix the incorrect
CONCAT
result in a statement involvingGROUP BY
#7448 - Fix the imprecise type length issue when casting the
DECIMAL
type to theSTRING
type #7451
- Support Session variables
- DML
- DDL
- Improve the method of DDL judging whether
Schema
is replicated to avoid misjudgement in some cases #7319 - Fix the
SHOW CREATE TABLE
result in adding index process #6993 - Allow the default value of
text
/blob
/json
to be NULL in non-restrictsql-mode
#7230 - Fix the
ADD INDEX
issue in some cases #7142 - Increase the speed of adding
UNIQUE-KEY
index operation largely #7132 - Fix the truncating issue of the prefix index in UTF-8 character set #7109
- Add the environment variable
tidb_ddl_reorg_priority
to control the priority of theadd-index
operation #7116 - Fix the display issue of
AUTO-INCREMENT
ininformation_schema.tables
#7037 - Support the
admin show ddl jobs <number>
command and support output specified number of DDL jobs #7028 - Support parallel DDL job execution #6955
- Improve the method of DDL judging whether
- Table Partition (Experimental)
- Support top level partition
- Support
Range Partition
PD
- Features
- Introduce the version control mechanism and support rolling update of the cluster with compatibility
- Enable the
region merge
feature - Support the
GetPrevRegion
interface - Support splitting Regions in batch
- Support storing the GC safepoint
- Improvements
- Optimize the issue that TSO allocation is affected by the system clock going backwards
- Optimize the performance of handling Region heartbeats
- Optimize the Region tree performance
- Optimize the performance of computing hotspot statistics
- Optimize returning the error code of API interface
- Add options of controlling scheduling strategies
- Prohibit using special characters in
label
- Improve the scheduling simulator
- Support splitting Regions using statistics in pd-ctl
- Support formatting JSON output by calling
jq
in pd-ctl - Add metrics about etcd Raft state machine
- Bug fixes
- Fix the issue that the namespace is not reloaded after switching Leader
- Fix the issue that namespace scheduling exceeds the schedule limit
- Fix the issue that hotspot scheduling exceeds the schedule limit
- Fix the issue that wrong logs are output when the PD client closes
- Fix the wrong statistics of Region heartbeat latency
TiKV
- Features
- Support
batch split
to avoid too large Regions caused by the Write operation on hot Regions - Support splitting Regions based on the number of rows to improve the index scan efficiency
- Support
- Performance
- Use
LocalReader
to separate the Read operation from the raftstore thread to lower the Read latency - Refactor the MVCC framework, optimize the memory usage and improve the scan Read performance
- Support splitting Regions based on statistics estimation to reduce the I/O usage
- Optimize the issue that the Read performance is affected by continuous Write operations on the rollback record
- Reduce the memory usage of pushdown aggregation computing
- Use
- Improvements
- Add the pushdown support for a large number of built-in functions and better charset support
- Optimize the GC workflow, improve the GC speed and decrease the impact of GC on the system
- Enable
prevote
to speed up service recovery when the network is abnormal - Add the related configuration items of RocksDB log files
- Adjust the default configuration of
scheduler_latch
- Support setting whether to compact the data in the bottom layer of RocksDB when using tikv-ctl to compact data manually
- Add the check for environment variables when starting TiKV
- Support dynamically configuring the
dynamic_level_bytes
parameter based on the existing data - Support customizing the log format
- Integrate tikv-fail in tikv-ctl
- Add I/O metrics of threads
- Bug fixes
- Fix decimal related issues
- Fix the issue that
gRPC max_send_message_len
is set mistakenly - Fix the issue caused by misconfiguration of
region_size
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