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TiDB 4.0.8 Release Notes
Release date: October 30, 2020
TiDB version: 4.0.8
New Features
TiDB
- Support the new aggregate function
APPROX_PERCENTILE
#20197
- Support the new aggregate function
TiFlash
- Support pushing down
CAST
functions
- Support pushing down
Tools
TiCDC
- Support snapshot-level consistent replication #932
Improvements
TiDB
- Prioritize low-selectivity indexes in the greedy search procedure of
Selectivity()
#20154 - Record more RPC runtime information in Coprocessor runtime statistics #19264
- Speed up parsing the slow log to improve query performance #20556
- Wait for timeout execution plans during the plan binding stage to record more debug information when the SQL optimizer is verifying potential new plans #20530
- Add the execution retry time in the slow log and the slow query result #20495 #20494
- Add the
table_storage_stats
system table #20431 - Add the RPC runtime statistical information for the
INSERT
/UPDATE
/REPLACE
statement #20430 - Add the operator information in the result of
EXPLAIN FOR CONNECTION
#20384 - Adjust the TiDB error log to the
DEBUG
level for the client connection/disconnection activities #20321 - Add monitoring metrics for Coprocessor Cache #20293
- Add the runtime information of pessimistic lock keys #20199
- Add two extra sections of time consumption information in the runtime information and
trace
span #20187 - Add the runtime information of transaction commit in the slow log #20185
- Disable the index merge join #20599
- Add the ISO 8601 and timezone supports for temporal string literals #20670
- Prioritize low-selectivity indexes in the greedy search procedure of
TiKV
- Add the Fast-Tune panel page to assist performance diagnostics #8804
- Add the
security.redact-info-log
configuration item, which redacts user data from logs #8746 - Reformat the metafile of error codes #8877
- Enable dynamically changing the
pessimistic-txn.pipelined
configuration #8853 - Enable the memory profiling features by default #8801
PD
TiFlash
- Add monitoring metrics of Raft logs
- Add monitoring metrics of memory usage for
cop
tasks - Make the
min
/max
index more accurate when data is deleted - Improve query performance in the case of a small data volume
- Add the
errors.toml
file to support the standard error code
Tools
Backup and Restore (BR)
TiCDC
- Print statistics in MySQL sink periodically #1023
Dumpling
TiDB Lightning
Bug Fixes
TiDB
- Fix the unexpected panic that occurs when using partitioned tables #20565
- Fix the wrong result of outer join when filtering the outer side using index merge join #20427
- Fix the issue that the
NULL
value is returned when converting data to theBIT
type if the data is too long #20363 - Fix the corrupted default value for the
BIT
type column #20340 - Fix the overflow error that might occur when converting the
BIT
type to theINT64
type #20312 - Fix the possible wrong result of the propagate column optimization for the hybrid type column #20297
- Fix the panic that might occur when storing outdated plans from the plan cache #20246
- Fix the bug that the returned result is mistakenly truncated if
FROM_UNIXTIME
andUNION ALL
are used together #20240 - Fix the issue that wrong results might be returned when the
Enum
type value is converted to theFloat
type #20235 - Fix the possible panic of
RegionStore.accessStore
#20210 - Fix the wrong result returned when sorting the maximum unsigned integer in
BatchPointGet
#20205 - Fix the bug that the coercibilities of
Enum
andSet
are wrong #20364 - Fix an issue of ambiguous
YEAR
conversion #20292 - Fix the issue of wrong reported result that occurs when the KV duration panel contains
store0
#20260 - Fix the issue that the
Float
type data is mistakenly inserted regardless of theout of range
error #20252 - Fix the bug that the generated column does not handle bad
NULL
values #20216 - Fix the inaccurate error information for the
YEAR
type data that is out of range #20170 - Fix the unexpected
invalid auto-id
error that might occur during the pessimistic transaction retry #20134 - Fix the issue that the constraint is not checked when using
ALTER TABLE
to change theEnum
/Set
type #20046 - Fix the wrong runtime information of
cop
tasks recorded when multiple operators are used for concurrency #19947 - Fix the issue that read-only system variables cannot be explicitly selected as the session variables #19944
- Fix the issue that the duplicate
ORDER BY
condition might cause sub-optimal execution plans #20333 - Fix the issue that the generated metric profile might fail if the font size exceeds the maximum allowable value #20637
TiKV
- Fix the bug that the mutex conflict in encryption causes pd-worker to process heartbeats slowly #8869
- Fix the issue that the memory profile is mistakenly generated #8790
- Fix the failure to back up databases on GCS when the storage class is specified #8763
- Fix the bug that a learner cannot find a leader when the Region is restarted or newly split #8864
PD
TiFlash
- Fix the issue of wrong timestamp in the log message
- Fix the issue that during the multi-disk TiFlash deployment, the wrong capacity causes the creation of TiFlash replicas to fail
- Fix the bug that TiFlash might throw errors about broken data files after restart
- Fix the issue that broken files might be left on disk after TiFlash crashes
- Fix the bug that it might take a long time to wait for index during learner reads if the proxy cannot catch up with the latest Raft lease information
- Fix the bug that the proxy writes too much Region state information to the key-value engine while replaying the outdated Raft log
Tools
Backup and Restore (BR)
- Fix the
send on closed channel
panic during restore #559
- Fix the
TiCDC
TiDB Lightning
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