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TiDB 5.0.4 Release Notes
Release Date: September 27, 2021
TiDB version: 5.0.4
Compatibility changes
TiDB
- Fix the issue that executing
SHOW VARIABLES
in a new session is slow. This fix reverts some changes made in #19341 and might cause compatibility issues. #24326 - Change the default value of the
tidb_stmt_summary_max_stmt_count
variable from200
to3000
#25873
- The following bug fixes change execution results, which might cause upgrade incompatibilities:
- Fix the issue that TiDB returns wrong result when the children of
UNION
contain theNULL
value #26559 - Fix the issue that
greatest(datetime) union null
returns empty string #26532 - Fix the issue that the behavior of the
last_day
function is incompatible in SQL mode #26000 - Fix the issue that the
having
clause might not work correctly #26496 - Fix the wrong execution results that occur when the collations around the
between
expression are different #27146 - Fix the wrong execution results that occur when the column in the
group_concat
function has a non-bin collation #27429 - Fix an issue that using a
count(distinct)
expression on multiple columns returns wrong result when the new collation is enabled #27091 - Fix the result wrong that occurs when the argument of the
extract
function is a negative duration #27236 - Fix the issue that inserting an invalid date does not report an error when the
SQL_MODE
is 'STRICT_TRANS_TABLES' #26762 - Fix the issue that using an invalid default date does not report an error when the
SQL_MODE
is 'NO_ZERO_IN_DATE' #26766 - Fix a bug on the query range of prefix index #26029
- Fix the issue that the
LOAD DATA
statement might abnormally import non-utf8 data #25979 - Fix the issue that
insert ignore on duplicate update
might insert wrong data when the secondary index has the same column with the primary key #25809 - Fix the issue that
insert ignore duplicate update
might insert wrong data when a partitioned table has a clustered index #25846 - Fix the issue that the query result might be wrong when the key is the
ENUM
type in point get or batch point get #24562 - Fix the wrong result that occurs when dividing a
BIT
-type value #23479 - Fix the issue that the results of
prepared
statements and direct queries might be inconsistent #22949 - Fix the issue that the query result might be wrong when a
YEAR
type is compared with a string or an integer type #23262
- Fix the issue that TiDB returns wrong result when the children of
- Fix the issue that executing
Feature enhancements
TiDB
- Support setting
tidb_enforce_mpp=1
to ignore the optimizer estimation and forcibly use the MPP mode #26382
- Support setting
TiKV
- Support changing TiCDC configurations dynamically #10645
PD
- Add OIDC-based SSO support for TiDB Dashboard #3884
TiFlash
- Support the
HAVING()
function in DAG requests - Support the
DATE()
function - Add Grafana panels for write throughput per instance
- Support the
Improvements
TiDB
- Trigger auto-analyze based on the histogram row count #24237
- Stop sending requests to a TiFlash node for a period if the node has failed and restarted before #26757
- Increase the
split region
upper limit to makesplit table
andpresplit
more stable #26657 - Support retry for MPP queries #26483
- Check the availability of TiFlash before launching MPP queries #1807
- Support the stable result mode to make the query result more stable #26084
- Support the MySQL system variable
init_connect
and its associated features #18894 - Thoroughly push down the
COUNT(DISTINCT)
aggregation function in the MPP mode #25861 - Print log warnings when the aggregation function cannot be pushed down in
EXPLAIN
statements #25736 - Add error labels for
TiFlashQueryTotalCounter
in Grafana dashboard #25327 - Support getting the MVCC data of a clustered index table through a secondary index by HTTP API #24209
- Optimize the memory allocation of
prepared
statement in parser #24371
TiKV
- Handle read ready and write ready separately to reduce read latency #10475
- Reduce the size of Resolved TS messages to save network bandwidth #2448
- Drop log instead of blocking threads when the slogger thread is overloaded and the queue is filled up #10841
- Make the slow log of TiKV coprocessor only consider the time spent on processing requests #10841
- Make prewrite as idempotent as possible to reduce the chance of undetermined errors #10587
- Avoid the false "GC can not work" alert under low write flow #10662
- Make the database to be restored always match the original cluster size during backup. #10643
- Ensure that the panic output is flushed to the log #9955
PD
- Improve the performance of synchronizing Region information between PDs #3993
Tools
Dumpling
- Support backing up MySQL-compatible databases that do not support the
START TRANSACTION ... WITH CONSISTENT SNAPSHOT
or theSHOW CREATE TABLE
syntax #309
- Support backing up MySQL-compatible databases that do not support the
TiCDC
- Optimize memory management when Unified Sorter is using memory to sort #2553
- Prohibit operating TiCDC clusters across major or minor versions #2598
- Reduce the goroutine usage when a table's Regions are all transferred away from a TiKV node #2284
- Remove
file sorter
#2326 - Always pull the old values from TiKV and the output is adjusted according to
enable-old-value
#2301 - Improve the error message returned when a PD endpoint misses the certificate #1973
- Optimize workerpool for fewer goroutines when concurrency is high #2211
- Add a global gRPC connection pool and share gRPC connections among KV clients #2533
Bug Fixes
TiDB
- Fix the issue that TiDB might panic when querying a partitioned table and the partition key has the
IS NULL
condition #23802 - Fix the issue that the overflow check of the
FLOAT64
type is different with that of MySQL #23897 - Fix the wrong character set and collation for the
case when
expression #26662 - Fix the issue that committing pessimistic transactions might cause write conflicts #25964
- Fix a bug that the index keys in a pessimistic transaction might be repeatedly committed #26359 #10600
- Fix the issue that TiDB might panic when resolving the async commit locks #25778
- Fix a bug that a column might not be found when using
INDEX MERGE
#25045 - Fix a bug that
ALTER USER REQUIRE SSL
clears users'authentication_string
#25225 - Fix a bug that the value of the
tidb_gc_scan_lock_mode
global variable on a new cluster shows "PHYSICAL" instead of the actual default mode "LEGACY" #25100 - Fix the bug that the
TIKV_REGION_PEERS
system table does not show the correctDOWN
status #24879 - Fix the issue of memory leaks that occurs when HTTP API is used #24649
- Fix the issue that views do not support
DEFINER
#24414 - Fix the issue that
tidb-server --help
exits with the code2
#24046 - Fix the issue that setting the global variable
dml_batch_size
does not take effect #24709 - Fix the issue that using
read_from_storage
and partitioned table at the same time causes an error #20372 - Fix the issue that TiDB panics when executing the projection operator #24264
- Fix the issue that statistics might cause queries to panic #24061
- Fix the issue that using the
approx_percentile
function on aBIT
column might panic #23662 - Fix the issue that the metrics on the Coprocessor Cache panel in Grafana are wrong #26338
- Fix the issue that concurrently truncating the same partition causes DDL statements to stuck #26229
- Fix the issue of wrong query results that occurs when the session variable is used as the
GROUP BY
item #27106 - Fix the wrong implicit conversion between
VARCHAR
and timestamp when joining tables #25902 - Fix the wrong results in associated subquery statements #27233
- Fix the issue that TiDB might panic when querying a partitioned table and the partition key has the
TiKV
- Fix the potential disk full issue caused by corrupted snapshot files #10813
- Fix the TiKV panic issue that occurs when upgrading from a pre-5.0 version with Titan enabled #10843
- Fix the issue that TiKV of a newer version cannot be rolled back to v5.0.x #10843
- Fix the TiKV panic issue that occurs when upgrading from a pre-5.0 version to a 5.0 version or later. If a cluster was upgraded from TiKV v3.x with Titan enabled before the upgrade, this cluster might encounter the issue. #10774
- Fix the parsing failure caused by the left pessimistic locks #26404
- Fix the panic that occurs when calculating duration on certain platforms #10571
- Fix the issue that the keys of
batch_get_command
in Load Base Split are unencoded #10542
PD
- Fix the issue that PD does not fix the down peers in time #4077
- Fix the issue that the replica count of the default placement rules stays constant after
replication.max-replicas
is updated #3886 - Fix a bug that PD might panic when scaling out TiKV #3868
- Fix the scheduling conflict issue that occurs when multiple schedulers are running at same time #3807
- Fix the issue that the scheduler might appear again even if it has been deleted #2572
TiFlash
- Fix the potential panic issue that occurs when running table scan tasks
- Fix the potential memory leak issue that occurs when executing MPP tasks
- Fix a bug that TiFlash raises the
duplicated region
error when handling DAQ requests - Fix the issue of unexpected results when executing the aggregation functions
COUNT
orCOUNT DISTINCT
- Fix the potential panic issue that occurs when executing MPP tasks
- Fix a potential bug that TiFlash cannot restore data when deployed on multiple disks
- Fix the potential panic issue that occurs when deconstructing
SharedQueryBlockInputStream
- Fix the potential panic issue that occurs when deconstructing
MPPTask
- Fix the issue of unexpected results when TiFlash fails to establish MPP connections
- Fix the potential panic issue that occurs when resolving locks
- Fix the issue that the store size in metrics is inaccurate under heavy writing
- Fix a bug of incorrect results that occurs when queries contain filters like
CONSTANT
,<
,<=
,>
,>=
, orCOLUMN
- Fix the potential issue that TiFlash cannot garbage-collect the delta data after running for a long time
- Fix a potential bug that metrics display wrong values
- Fix the potential issue of data inconsistency that occurs when TiFlash is deployed on multiple disks
Tools
Dumpling
- Fix the issue that the execution of
show table status
is stuck in MySQL 8.0.3 or a later version #322
- Fix the issue that the execution of
TiCDC
- Fix the issue of process panic that occurs when encoding the data types such as
mysql.TypeString, mysql.TypeVarString, mysql.TypeVarchar
into JSON #2758 - Fix a data inconsistency issue that occurs because multiple processors might write data to the same table when this table is being re-scheduled #2417
- Decrease the gRPC window size to avoid the OOM that occurs when TiCDC captures too many Regions #2724
- Fix the error that the gRPC connection is frequently broken when the memory pressure is high #2202
- Fix a bug that causes TiCDC to panic on the unsigned
TINYINT
type #2648 - Fix the issue that TiCDC Open Protocol outputs an empty value when inserting a transaction and deleting data of the same row in the upstream #2612
- Fix a bug that DDL handling fails when a changefeed starts at the finish TS of a schema change #2603
- Fix the issue that irresponsive downstreams interrupt the replication task in old owner until the task times out #2295
- Fix a bug in metadata management #2558
- Fix the issue of data inconsistency that occurs after the TiCDC owner switch #2230
- Fix the issue that outdated capture might appear in the output of the
capture list
command #2388 - Fix the
ErrSchemaStorageTableMiss
error that occurs when the DDL Job duplication is encountered in the integrated test #2422 - Fix the bug that a changefeed cannot be removed if the
ErrGCTTLExceeded
error occurs #2391 - Fix a bug that replicating large tables to cdclog fails #1259 #2424
- Fix the CLI backward compatibility issue #2373
- Fix the issue of insecure concurrent access to the map in
SinkManager
#2299 - Fix the issue of potential DDL loss when the owner crashes when executing DDL statements #1260
- Fix the issue that the lock is resolved immediately after a Region is initialized #2188
- Fix the issue of extra partition dispatching that occurs when adding a new partitioned table #2263
- Fix the issue that TiCDC keeps warning on removed changefeeds #2156
- Fix the issue of process panic that occurs when encoding the data types such as
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