TiDB 5.2.4 Release Notes
Release Date: April 26, 2022
TiDB version: 5.2.4
Compatibility changes
TiDB
- Change the default value of the system variable
tidb_analyze_version
from2
to1
#31748
- Change the default value of the system variable
TiKV
- Add
raft-log-compact-sync-interval
to control the time interval ("2s"
by default) to compact unnecessary Raft logs #11404 - Change the default value of
raft-log-gc-tick-interval
from"10s"
to"3s"
#11404 - When
storage.flow-control.enable
is set totrue
, the value ofstorage.flow-control.hard-pending-compaction-bytes-limit
overwrites that ofrocksdb.(defaultcf|writecf|lockcf).hard-pending-compaction-bytes-limit
#11424
- Add
Tools
TiDB Lightning
- Change the default value of
regionMaxKeyCount
from 1_440_000 to 1_280_000, to avoid too many empty Regions after data import #30018
- Change the default value of
Improvements
TiKV
- Transfer the leadership to CDC observer to reduce latency jitter #12111
- Reduce the TiCDC recovery time by reducing the number of the Regions that require the Resolve Locks step #11993
- Update the proc filesystem (procfs) to v0.12.0 #11702
- Speed up the Garbage Collection (GC) process by increasing the write batch size when performing GC to Raft logs #11404
- Increase the speed of inserting SST files by moving the verification process to the
Import
thread pool from theApply
thread pool #11239
Tools
TiCDC
- Change the default value of Kafka Sink
partition-num
to 3 so that TiCDC distributes messages across Kafka partitions more evenly #3337 - Reduce the time for the KV client to recover when a TiKV store is down #3191
- Add a
Lag analyze
panel in Grafana #4891 - Expose configuration parameters of the Kafka producer to make them configurable in TiCDC #4385
- Add the exponential backoff mechanism for restarting a changefeed #3329
- Reduce the count of "EventFeed retry rate limited" logs #4006
- Set the default value of
max-message-bytes
to 10M #4041 - Add more Prometheus and Grafana monitoring metrics and alerts, including
no owner alert
,mounter row
,table sink total row
, andbuffer sink total row
#4054 #1606 - Support multiple Kubernetes clusters in Grafana dashboards #4665
- Add catch-up ETA (Estimated Time of Arrival) to the
changefeed checkpoint
monitoring metric #5232
- Change the default value of Kafka Sink
Bug fixes
TiDB
- Fix wrong range calculation results for Nulleq function on Enum values #32428
- Fix the issue that INDEX HASH JOIN returns the
send on closed channel
error #31129 - Fix the issue that concurrent column type change causes inconsistency between the schema and the data #31048
- Fix the issue of potential data index inconsistency in optimistic transaction mode #30410
- Fix the issue that a SQL operation is canceled when its JSON type column joins its
CHAR
type column #29401 - Fix the issue that window functions might return different results when using a transaction or not #29947
- Fix the issue that the
Column 'col_name' in field list is ambiguous
error is reported unexpectedly when a SQL statement contains natural join #25041 - Fix the issue that the length information is wrong when casting
Decimal
toString
#29417 - Fix the issue that the
GREATEST
function returns inconsistent results due to different values oftidb_enable_vectorized_expression
(set toon
oroff
) #29434 - Fix wrong results of deleting data of multiple tables using
left join
#31321 - Fix a bug that TiDB may dispatch duplicate tasks to TiFlash #32814
- Fix the MPP task list empty error when executing a query #31636
- Fix wrong results of index join caused by an innerWorker panic #31494
- Fix the issue that executing the
INSERT ... SELECT ... ON DUPLICATE KEY UPDATE
statement gets panic #28078 - Fix wrong query results due to the optimization of
Order By
#30271 - Fix the wrong result that might occur when performing
JOIN
onENUM
type columns #27831 - Fix the panic when using the
CASE WHEN
function on theENUM
data type #29357 - Fix wrong results of the
microsecond
function in vectorized expressions #29244 - Fix the issue that the window function causes TiDB to panic instead of reporting an error #30326
- Fix the issue that the Merge Join operator gets wrong results in certain cases #33042
- Fix the issue that TiDB gets a wrong result when a correlated subquery returns a constant #32089
- Fix the issue that TiDB writes wrong data due to the wrong encoding of the
ENUM
orSET
column #32302 - Fix the issue that the
MAX
orMIN
function on theENUM
orSET
column returns a wrong result when the new collation is enabled in TiDB #31638 - Fix the issue that the IndexHashJoin operator does not exit successfully #31062
- Fix the issue that TiDB might read wrong data when a table has a virtual column #30965
- Fix the issue that the setting of the log level does not take effect on the slow query log #30309
- Fix the issue that partitioned tables cannot fully use indexes to scan data in some cases #33966
- Fix the issue that the background HTTP service of TiDB might not exit successfully and makes the cluster in an abnormal state #30571
- Fix the issue that TiDB might unexpectedly output many logs of failed authentication #29709
- Fix the issue that the system variable
max_allowed_packet
does not take effect #31422 - Fix the issue that the
REPLACE
statement incorrectly changes other rows when the auto ID is out of range #29483 - Fix the issue that the slow query log cannot output log normally and might consume too much memory #32656
- Fix the issue that the result of NATURAL JOIN might include unexpected columns #24981
- Fix the issue that using
ORDER BY
andLIMIT
together in one statement might output wrong results if a prefix-column index is used to query data #29711 - Fix the issue that the DOUBLE type auto-increment column might be changed when the optimistic transaction retries #29892
- Fix the issue that the STR_TO_DATE function cannot handle the preceding zero of the microsecond part correctly #30078
- Fix the issue that TiDB gets the wrong result when using TiFlash to scan tables with empty range although TiFlash does not support reading tables with empty range yet #33083
TiKV
- Fix a bug that stale messages cause TiKV to panic #12023
- Fix the issue of intermittent packet loss and out of memory (OOM) caused by the overflow of memory metrics #12160
- Fix the potential panic issue that occurs when TiKV performs profiling on Ubuntu 18.04 #9765
- Fix the issue that tikv-ctl returns an incorrect result due to its wrong string match #12329
- Fix a bug that replica reads might violate the linearizability #12109
- Fix a bug that TiKV might panic if it has been running for 2 years or more #11940
- Fix the issue of QPS drop when flow control is enabled and
level0_slowdown_trigger
is set explicitly #11424 - Fix the panic issue that occurs when the cgroup controller is not mounted #11569
- Fix possible metadata corruption caused by Region merge on a lagging Region peer #11526
- Fix the issue that the latency of Resolved TS increases after TiKV stops operating #11351
- Fix a panic issue that occurs when Region merge, ConfChange, and Snapshot happen at the same time in extreme conditions #11475
- Fix a bug that tikv-ctl cannot return the correct Region-related information #11393
- Fix the issue of negative sign when the decimal divide result is zero #29586
- Fix the issue that retrying prewrite requests in the pessimistic transaction mode might cause the risk of data inconsistency in rare cases #11187
- Fix a memory leak caused by monitoring data of statistics threads #11195
- Fix the issue that the average latency of the by-instance gRPC requests is inaccurate in TiKV metrics #11299
- Fix the panic issue caused by deleting snapshot files when the peer status is
Applying
#11746 - Fix a bug that TiKV cannot delete a range of data (which means the internal command
unsafe_destroy_range
is executed) when the GC worker is busy #11903 - Fix the issue that deleting an uninitialized replica might cause an old replica to be recreated #10533
- Fix the issue that TiKV cannot detect the memory lock when TiKV performs a reverse table scan #11440
- Fix the deadlock issue that happens occasionally when coroutines run too fast #11549
- Fix the issue that destroying a peer might cause high latency #10210
- Fix the issue that TiKV panics and destroys peers unexpectedly because the target Region to be merged is invalid #12232
- Fix the TiKV panic issue that occurs when the target peer is replaced with the peer that is destroyed without being initialized when merging a Region #12048
- Fix the TiKV panic issue that occurs when applying snapshot is aborted #11618
- Fix a bug that TiKV cannot correctly calculate the number of snapshots being sent when the operator execution fails #11341
PD
TiFlash
- Fix a bug that MPP tasks might leak threads forever #4238
- Fix the issue that the result of
IN
is incorrect in multi-value expressions #4016 - Fix the issue that the date format identifies
'\n'
as an invalid separator #4036 - Fix the potential query error after adding columns under heavy read workload #3967
- Fix the bug that invalid storage directory configurations lead to unexpected behaviors #4093
- Fix the bug that some exceptions are not handled properly #4101
- Fix the bug that the
STR_TO_DATE()
function incorrectly handles leading zeros when parsing microseconds #3557 - Fix the issue that casting
INT
toDECIMAL
might cause overflow #3920 - Fix the wrong result that occurs when casting
DATETIME
toDECIMAL
#4151 - Fix the overflow that occurs when casting
FLOAT
toDECIMAL
#3998 - Fix the issue that the
CastStringAsReal
behavior is inconsistent in TiFlash and in TiDB or TiKV #3475 - Fix the issue that the
CastStringAsDecimal
behavior is inconsistent in TiFlash and in TiDB or TiKV #3619 - Fix the issue that TiFlash might return the
EstablishMPPConnection
error after it is restarted #3615 - Fix the issue that obsolete data cannot be reclaimed after setting the number of TiFlash replicas to 0 #3659
- Fix potential data inconsistency when widening the primary key column with the primary key being
handle
#3569 - Fix possible parsing errors when an SQL statement contains extremely long nested expressions #3354
- Fix possible wrong results when a query contains the
where <string>
clause #3447 - Fix possible wrong results when
new_collations_enabled_on_first_bootstrap
is enabled #3388, #3391 - Fix the panic issue that occurs when TLS is enabled #4196
- Fix the panic issue that occurs when the memory limit is enabled #3902
- Fix the issue that TiFlash crashes occasionally when an MPP query is stopped #3401
- Fix the unexpected error of
Unexpected type of column: Nullable(Nothing)
#3351 - Fix possible metadata corruption caused by Region merge on a lagging Region peer #4437
- Fix the issue that a query containing
JOIN
might be hung if an error occurs #4195 - Fix possible wrong results returned for MPP queries due to incorrect execution plans #3389
Tools
Backup & Restore (BR)
- Fix the issue that BR fails to back up RawKV #32607
TiCDC
- Fix the issue that default values cannot be replicated #3793
- Fix a bug that sequence is incorrectly replicated in some cases #4563
- Fix a bug that a TiCDC node exits abnormally when a PD leader is killed #4248
- Fix a bug that MySQL sink generates duplicated
replace
SQL statements whenbatch-replace-enable
is disabled #4501 - Fix the issue of panic and data inconsistency that occurs when outputting the default column value #3929
- Fix the issue that
mq sink write row
does not have monitoring data #3431 - Fix the issue that replication cannot be performed when
min.insync.replicas
is smaller thanreplication-factor
#3994 - Fix the potential panic issue that occurs when a replication task is removed #3128
- Fix the bug that HTTP API panics when the required processor information does not exist #3840
- Fix the issue of potential data loss caused by inaccurate checkpoint #3545
- Fix the potential issue that the deadlock causes a replication task to get stuck #4055
- Fix the TiCDC panic issue that occurs when manually cleaning the task status in etcd #2980
- Fix the issue that special comments in DDL statements cause the replication task to stop #3755
- Fix the issue of replication stop caused by the incorrect configuration of
config.Metadata.Timeout
#3352 - Fix the issue that the service cannot be started because of a timezone issue in the RHEL release #3584
- Fix the issue that
stopped
changefeeds resume automatically after a cluster upgrade #3473 - Fix the issue of overly frequent warnings caused by MySQL sink deadlock #2706
- Fix the bug that the
enable-old-value
configuration item is not automatically set totrue
on Canal and Maxwell protocols #3676 - Fix the issue that Avro sink does not support parsing JSON type columns #3624
- Fix the negative value error in the changefeed checkpoint lag #3010
- Fix the OOM issue in the container environment #1798
- Fix the memory leak issue after processing DDLs #3174
- Fix the issue that changefeed gets stuck when tables are repeatedly scheduled in the same node #4464
- Fix a bug that querying status through open API may be blocked when the PD node is abnormal #4778
- Fix incorrect metrics caused by owner changes #4774
- Fix a stability problem in workerpool used by Unified Sorter #4447
- Fix the issue that the
cached region
monitoring metric is negative #4300
TiDB Lightning
- Fix the issue of wrong import result that occurs when TiDB Lightning does not have the privilege to access the
mysql.tidb
table #31088 - Fix the checksum error “GC life time is shorter than transaction duration” #32733
- Fix a bug that TiDB Lightning may not delete the metadata schema when some import tasks do not contain source files #28144
- Fix the issue that TiDB Lightning does not report errors when the S3 storage path does not exist #28031 #30709
- Fix an error that occurs when iterating more than 1000 keys on GCS #30377
- Fix the issue of wrong import result that occurs when TiDB Lightning does not have the privilege to access the