TiDB 6.5.6 Release Notes
Release date: December 7, 2023
TiDB version: 6.5.6
Quick access: Quick start | Production deployment
Compatibility changes
- Prohibit setting
require_secure_transport
toON
in Security Enhanced Mode (SEM) to prevent potential connectivity issues for users #47665 @tiancaiamao - Introduce the
tidb_opt_enable_hash_join
system variable to control whether the optimizer selects hash joins for tables #46695 @coderplay - After further testing, the default value of the TiCDC Changefeed configuration item
case-sensitive
is changed fromtrue
tofalse
. This means that by default, table and database names in the TiCDC configuration file are case-insensitive #10047 @sdojjy - TiCDC Changefeed introduces the following new configuration items:
sql-mode
: enables you to set the SQL mode used by TiCDC to parse DDL statements when TiCDC replicates data #9876 @asddongmenencoding-worker-num
andflush-worker-num
: enables you to set different concurrency parameters for the redo module based on specifications of different machines #10048 @CharlesCheung96compression
: enables you to configure the compression behavior of redo log files #10176 @sdojjychangefeed-error-stuck-duration
: enables you to set the duration for which the changefeed is allowed to automatically retry when internal errors or exceptions occur #9875 @asddongmensink.cloud-storage-config
: enables you to set the automatic cleanup of historical data when replicating data to object storage #10109 @CharlesCheung96
Improvements
TiDB
- Support the
FLASHBACK CLUSTER TO TSO
syntax #48372 @BornChanger
- Support the
TiKV
PD
Tools
Backup & Restore (BR)
- During restoring a snapshot backup, BR retries when it encounters certain network errors #48528 @Leavrth
- Introduce a new integration test for Point-In-Time Recovery (PITR) in the
delete range
scenario, enhancing PITR stability #47738 @Leavrth - Enable automatic retry of Region scatter during snapshot recovery when encountering timeout failures or cancellations of Region scatter #47236 @Leavrth
- BR can pause Region merging by setting the
merge-schedule-limit
configuration to0
#7148 @BornChanger
TiCDC
- Support making TiCDC Canal-JSON content format compatible with the content format of the official Canal output by setting
content-compatible=true
in thesink-uri
configuration #10106 @3AceShowHand - Optimize the execution logic of replicating the
ADD INDEX
DDL operations to avoid blocking subsequent DML statements #9644 @sdojjy - Reduce the impact of TiCDC incremental scanning on upstream TiKV #11390 @hicqu
- Support making TiCDC Canal-JSON content format compatible with the content format of the official Canal output by setting
Bug fixes
TiDB
- Fix the issue that the chunk cannot be reused when the HashJoin operator performs probe #48082 @wshwsh12
- Fix the issue that
Duplicate entry
might occur whenAUTO_ID_CACHE=1
is set #46444 @tiancaiamao - Fix the issue that the
TIDB_INLJ
hint does not take effect when joining two sub-queries #46160 @qw4990 - Fix the issue that DDL operations might get stuck after TiDB is restarted #46751 @wjhuang2016
- Fix the issue that DDL operations might get permanently blocked due to incorrect MDL handling #46920 @wjhuang2016
- Fix the issue that the results of
MERGE_JOIN
are incorrect #46580 @qw4990 - Fix the issue that the Sort operator might cause TiDB to crash during the spill process #47538 @windtalker
- Fix the issue that the
cast(col)=range
condition causes FullScan when CAST has no precision loss #45199 @AilinKid - Fix the panic issue of
batch-client
inclient-go
#47691 @crazycs520 - Prohibit split table operations on non-integer clustered indexes #47350 @tangenta
- Fix the incompatibility issue between the behavior of prepared plan cache and non-prepared plan cache during time conversion #42439 @qw4990
- Fix the issue that sometimes an index cannot be created for an empty table using ingest mode #39641 @tangenta
- Fix the issue of not being able to detect data that does not comply with partition definitions during partition exchange #46492 @mjonss
- Fix the issue that
GROUP_CONCAT
cannot parse theORDER BY
column #41986 @AilinKid - Fix the issue that HashCode is repeatedly calculated for deeply nested expressions, which causes high memory usage and OOM #42788 @AilinKid
- Fix the issue that when Aggregation is pushed down through Union in MPP execution plans, the results are incorrect #45850 @AilinKid
- Fix the issue of incorrect memory usage estimation in
INDEX_LOOKUP_HASH_JOIN
#47788 @SeaRise - Fix the issue that the zip file generated by
plan replayer
cannot be imported back into TiDB #46474 @YangKeao - Fix the incorrect cost estimation caused by an excessively large
N
inLIMIT N
#43285 @qw4990 - Fix the panic issue that might occur when constructing TopN structure for statistics #35948 @hi-rustin
- Fix the issue that the result of
COUNT(INT)
calculated by MPP might be incorrect #48643 @AilinKid - Fix the issue that panic might occur when
tidb_enable_ordered_result_mode
is enabled #45044 @qw4990 - Fix the issue that the optimizer mistakenly selects IndexFullScan to reduce sort introduced by window functions #46177 @qw4990
- Fix the issue that the result might be incorrect when predicates are pushed down to common table expressions #47881 @winoros
- Fix the issue that executing
UNION ALL
with the DUAL table as the first subnode might cause an error #48755 @winoros - Fix the issue that column pruning can cause panic in specific situations #47331 @hi-rustin
- Fix the issue of possible syntax error when a common table expression (CTE) containing aggregate or window functions is referenced by other recursive CTEs #47603 #47711 @elsa0520
- Fix the issue that an exception might occur when using the
QB_NAME
hint in a prepared statement #46817 @jackysp - Fix the issue of Goroutine leak when using
AUTO_ID_CACHE=1
#46324 @tiancaiamao - Fix the issue that TiDB might panic when shutting down #32110 @july2993
- Fix the issue of not handling locks in the MVCC interface when reading schema diff commit versions from the TiDB schema cache #48281 @cfzjywxk
- Fix the issue of duplicate rows in
information_schema.columns
caused by renaming a table #47064 @jiyfhust - Fix the bugs in the
LOAD DATA REPLACE INTO
statement #47995) @lance6716 - Fix the issue of
IMPORT INTO
task failure caused by PD leader malfunction for 1 minute #48307 @D3Hunter - Fix the issue of
ADMIN CHECK
failure caused by creating an index on a date type field #47426 @tangenta - Fix the issue of unsorted row data returned by
TABLESAMPLE
#48253 @tangenta - Fix the TiDB node panic issue that occurs when DDL
jobID
is restored to 0 #46296 @jiyfhust
TiKV
- Fix the issue that moving a peer might cause the performance of the Follower Read to deteriorate #15468 @YuJuncen
- Fix the data error of continuously increasing raftstore-applys #15371 @Connor1996
- Fix the issue that requests of the TiDB Lightning checksum coprocessor time out when there is online workload #15565 @lance6716
- Fix security issues by upgrading the version of
lz4-sys
to 1.9.4 #15621 @SpadeA-Tang - Fix security issues by upgrading the version of
tokio
to 6.5 #15621 @LykxSassinator - Fix security issues by removing the
flatbuffer
#15621 @tonyxuqqi - Fix the issue that resolved-ts lag increases when TiKV stores are partitioned #15679 @hicqu
- Fix the TiKV OOM issue that occurs when restarting TiKV and there are a large number of Raft logs that are not applied #15770 @overvenus
- Fix the issue that stale peers are retained and block resolved-ts after Regions are merged #15919 @overvenus
- Fix the issue that the scheduler command variables are incorrect in Grafana on the cloud environment #15832 @Connor1996
- Fix the issue that
blob-run-mode
in Titan cannot be updated online #15978 @tonyxuqqi - Fix the issue that TiKV panics due to inconsistent metadata between Regions #13311 @cfzjywxk
- Fix the issue that TiKV panics when the leader is forced to exit during Online Unsafe Recovery #15629 @Connor1996
- Fix the issue that the joint state of DR Auto-Sync might time out when scaling out #15817 @Connor1996
- Fix the issue that TiKV coprocessor might return stale data when removing a Raft peer #16069 @overvenus
- Fix the issue that resolved-ts might be blocked for 2 hours #39130 @overvenus
- Fix the issue that Flashback might get stuck when encountering
notLeader
orregionNotFound
#15712 @HuSharp
PD
- Fix potential security risks of the plugin directory and files #7094 @HuSharp
- Fix the issue that modified isolation levels are not synchronized to the default placement rules #7121 @rleungx
- Fix the issue that
evict-leader-scheduler
might lose configuration #6897 @HuSharp - Fix the issue that the method for counting empty Regions might cause Regions to be unbalanced during the recovery process of BR #7148 @Cabinfever
- Fix the issue that
canSync
andhasMajority
might be calculated incorrectly for clusters adopting the Data Replication Auto Synchronous (DR Auto-Sync) mode when the configuration of Placement Rules is complex #7201 @disksing - Fix the issue that
available_stores
is calculated incorrectly for clusters adopting the Data Replication Auto Synchronous (DR Auto-Sync) mode #7221 @disksing - Fix the issue that the primary AZ cannot add TiKV nodes when the secondary AZ is down for clusters adopting the Data Replication Auto Synchronous (DR Auto-Sync) mode #7218 @disksing
- Fix the issue that adding multiple TiKV nodes to a large cluster might cause TiKV heartbeat reporting to become slow or stuck #7248 @rleungx
- Fix the issue that PD might delete normal Peers when TiKV nodes are unavailable #7249 @lhy1024
- Fix the issue that it takes a long time to switch the leader in DR Auto-Sync mode #6988 @HuSharp
- Upgrade the version of Gin Web Framework from v1.8.1 to v1.9.1 to fix some security issues #7438 @niubell
TiFlash
- Fix the issue that the
max_snapshot_lifetime
metric is displayed incorrectly on Grafana #7713 @JaySon-Huang - Fix the issue that executing the
ALTER TABLE ... EXCHANGE PARTITION ...
statement causes panic #8372 @JaySon-Huang - Fix the issue that the memory usage reported by MemoryTracker is inaccurate #8128 @JinheLin
- Fix the issue that the
Tools
Backup & Restore (BR)
- Fix the issue that the log backup might get stuck in some scenarios when backing up large wide tables #15714 @YuJuncen
- Fix the issue that frequent flushes cause log backup to get stuck #15602 @3pointer
- Fix the issue that the retry after an EC2 metadata connection reset cause degraded backup and restore performance #46750 @Leavrth
- Fix the issue that running PITR multiple times within 1 minute might cause data loss #15483 @YuJuncen
- Fix the issue that the default values for BR SQL commands and CLI are different, which might cause OOM issues #48000 @YuJuncen
- Fix the issue that log backup might panic when the PD owner is transferred #47533 @YuJuncen
- Fix the issue that BR generates incorrect URIs for external storage files #48452 @3AceShowHand
TiCDC
- Fix the issue that TiCDC server might panic when executing lossy DDL statements in upstream #9739 @hicqu
- Fix the issue that the replication task reports an error when executing
RESUME
with the redo log feature enabled #9769 @hicqu - Fix the issue that replication lag becomes longer when the TiKV node crashes #9741 @sdojjy
- Fix the issue that the
WHERE
statement does not use the primary key as the condition when replicating data to TiDB or MySQL #9988 @asddongmen - Fix the issue that the workload of a replication task is not distributed evenly across TiCDC nodes #9839 @3AceShowHand
- Fix the issue that the interval between replicating DDL statements is too long when redo log is enabled #9960 @CharlesCheung96
- Fix the issue that the changefeed cannot replicate DML events in bidirectional replication mode if the target table is dropped and then recreated in upstream #10079 @asddongmen
- Fix the issue that the replication lag becomes longer due to too many NFS files when replicating data to an object storage service #10041 @CharlesCheung96
- Fix the issue that the TiCDC server might panic when replicating data to an object storage service #10137 @sdojjy
- Fix the issue that TiCDC accesses the invalid old address during PD scaling up and down #9584 @fubinzh @asddongmen
- Fix the issue that fetching wrong memory information might cause OOM issues in some operating systems #9762 @sdojjy
TiDB Data Migration (DM)
- Fix the issue that DM skips partition DDLs in optimistic mode #9788 @GMHDBJD
- Fix the issue that DM cannot properly track upstream table schemas when skipping online DDLs #9587 @GMHDBJD
- Fix the issue that replication lag returned by DM keeps growing when a failed DDL is skipped and no subsequent DDLs are executed #9605 @D3Hunter
- Fix the issue that DM skips all DMLs when resuming a task in optimistic mode #9588 @GMHDBJD
TiDB Lightning
- Fix the issue that data import fails when encountering the
write to tikv with no leader returned
error #45673 @lance6716 - Fix the issue that data import fails because HTTP retry requests do not use the current request content #47930 @lance6716
- Fix the issue that TiDB Lightning gets stuck during
writeToTiKV
#46321 @lance6716 - Remove unnecessary
get_regions
calls in physical import mode #45507 @mittalrishabh
- Fix the issue that data import fails when encountering the
TiDB Binlog