TiDB 4.0.13 Release Notes

Release date: May 28, 2021

TiDB version: 4.0.13

New Features

• TiDB

  • Support changing an AUTO_INCREMENT column to an AUTO_RANDOM one #24608
  • Add the infoschema.client_errors_summary tables to help users keep track of the errors that have been returned to clients #23267

Improvements

• TiDB

  • Avoid frequently reading the mysql.stats_histograms table if the cached statistics is up-to-date to avoid high CPU usage #24352

• TiKV

  • Make the calculation process of store used size more precise #9904
  • Set more Regions in the EpochNotMatch message to reduce Region misses #9731
  • Speed up freeing the memory accumulated in the long-running cluster #10035

• PD

  • Optimize the metrics of TSO processing time to help users determine whether the TSO processing time at the PD side is too long #3524
  • Update the dashboard version to v2021.03.12.1 #3469

• TiFlash

  • Automatically clean archived data to free up disk space

• Tools

  • Backup & Restore (BR)

    • Support backing up user tables created in the mysql schema #1077
    • Update checkVersion to check the cluster data and the backup data #1090
    • Tolerate a small number of TiKV node failures during backup #1062

  • TiCDC

    • Implement the processor flow control to avoid memory overflow (OOM) #1751
    • Support cleaning up stale temporary files in Unified Sorter and prevent multiple cdc server instances from sharing the same sort-dir directory #1741
    • Add the HTTP handler for the failpoint #1732

Bug Fixes

• TiDB

  • Fix the panic issue that occurs when the UPDATE statement with a subquery updates the generated column #24658
  • Fix the issue that causes duplicate query results when using the multi-column index for data reads #24634
  • Fix the issue that causes wrong query result when using the BIT type constant as the divisor in the DIV expression #24266
  • Fix the issue that the NO_ZERO_IN_DATE SQL mode does not take effect for the default column value set in DDL statements #24185
  • Fix an issue which causes wrong query results when using UNION between a BIT type column and an INTEGER type column #24026
  • Fix the issue that the TableDual plans are mistakenly created when comparing the BINARY type and the CHAR type #23917
  • Fix the issue that the insert ignore on duplicate statement might unexpectedly delete table records #23825
  • Fix the issue that the Audit plugin causes TiDB panic #23819
  • Fix the issue that the HashJoin operator incorrectly processes the collation #23812
  • Fix the issue of disconnection that occurs when batch_point_get incorrectly handles abnormal values in the pessimistic transaction #23778
  • Fix the issue of inconsistent indexes that occurs when the tidb_row_format_version configuration value is set to 1 and the enable_new_collation value is set to true #23772
  • Fix a bug that occurs when comparing the INTEGER type column with the STRING constant value #23705
  • Fix the error that occurs when the BIT type column is passed into the approx_percent function #23702
  • Fix a bug that causes TiDB to mistakenly report the TiKV server timeout error when executing TiFlash batch requests #23700
  • Fix the issue that the IndexJoin operator returns wrong results on the prefix column index #23691
  • Fix the issue which causes wrong query results because the collation on the BINARY type column is not properly handled #23598
  • Fix the issue of query panic that occurs when the UPDATE statement contains the join query with the HAVING clause #23575
  • Fix the issue that causes TiFlash to return wrong results when using the NULL constant in the comparison expression #23474
  • Fix the issue of wrong results when comparing the YEAR type column with the STRING constant #23335
  • Fix the issue that group_concat panics when session.group_concat_max_len is set too small #23257
  • Fix the issue of wrong query results that occurs when using the BETWEEN expression for the TIME type column #23233
  • Fix the issue of privilege check in the DELETE statements #23215
  • Fix the issue that no error is reported when inserting invalid strings to the DECIMAL type column #23196
  • Fix the issue of parsing error occurred when inserting data to the DECIMAL type columns #23152
  • Fix the issue that the USE_INDEX_MERGE hint does not take effect #22924
  • Fix a bug that the query returns wrong results when using ENUM or SET columns in the WHERE clause as an filter #22814
  • Fix a bug that the query returns wrong results when using the clustered index and the new collation at the same time #21408
  • Fix the panic that occurs when executing ANALYZE with enable_new_collation enabled #21299
  • Fix the issue that SQL views does not correctly handle the default roles associated with the SQL DEFINER #24531
  • Fix the issue that cancelling DDL jobs gets stuck #24445
  • Fix the issue that the concat function incorrectly handles the collation #24300
  • Fix a bug that the query returns wrong results when the SELECT field has an IN subquery and the subquery's outer side contains NULL tuples #24022
  • Fix a bug that TiFlash is chosen wrongly by the optimizer when TableScan is in descending order #23974
  • Fix a bug that the point_get plan returns the column name that is inconsistent with that of MySQL #23970
  • Fix the issue that executing the show table status statement on a database with a upper-cased name returns wrong results #23958
  • Fix a bug that the users who do not have the INSERT and DELETE privileges on a table at the same time can perform the REPLACE operation #23938
  • Fix the issue that the results of the concat/make_set/insert expressions are wrong because the collation is incorrectly handled #23878
  • Fix the panic that occurs when executing a query on the table that has RANGE partitions #23689
  • Fix the issue: In the cluster of an earlier version, if the tidb_enable_table_partition variable is set to false, the tables that contain partitions are handled as non-partitioned tables. Executing batch point get queries on this table, when the cluster is upgraded to a later version, causes connection panic. #23682
  • Fix the issue that when TiDB is configured to listen on TCP and UNIX sockets, the remote hosts over the TCP connection are not correctly validated for connection #23513
  • Fix a bug that the non-default collation causes wrong query results #22923
  • Fix a bug that the Coprocessor Cache panel of Grafana does not work #22617
  • Fix the error that occurs when the optimizer accesses the statistic cache #22565

• TiKV

  • Fix a bug that TiKV cannot start if the file_dict file is not fully written into the disk that has been full #9963
  • Limit TiCDC's scan speed at 128MB/s by default #9983
  • Reduce the memory usage of TiCDC's initial scan #10133
  • Support the back pressure for TiCDC's scan speed #10142
  • Fix a potential OOM issue by avoiding unnecessary reads to get TiCDC old values #10031
  • Fix a TiCDC OOM issue caused by reading old values #10197
  • Add a timeout mechanism for S3 storages to avoid the client hanging without responses #10132

• TiFlash

  • Fix the issue that number of delta-merge-tasks is not reported to Prometheus
  • Fix the TiFlash panic issue that occurs during Segment Split
  • Fix the issue that the Region write Duration (write blocks) panel in Grafana is shown in a wrong place
  • Fix the potential issue that the storage engine fails to remove data
  • Fix the issue of incorrect results when casting the TIME type to the INTEGER type
  • Fix a bug that the behavior of the bitwise operator is different from that of TiDB
  • Fix the issue of incorrect results when casting the STRING type to the INTEGER type
  • Fix the issue that consecutive and fast writes might make TiFlash out of memory
  • Fix the potential issue that the exception of null pointer might be raised during the table GC
  • Fix the TiFlash panic issue that occurs when writing data to dropped tables
  • Fix the TiFlash panic issue that occurs during BR restore
  • Fix a bug that the weights of some characters are wrong when using the general CI collation
  • Fix the potential issue that data will be lost in tombstoned tables
  • Fix the issue of incorrect results when comparing the string which contains zero bytes
  • Fix the issue that the logical function returns wrong results if the input column contains null constants
  • Fix the issue that the logical function only accepts the numeric type
  • Fix the issue of incorrect results that occurs when the timestamp value is 1970-01-01 and the timezone offset is negative
  • Fix the issue that hash value of Decimal256 is not stable

• Tools

  • TiCDC

    • Fix the deadlock issue caused by the flow control when the sorter's input channel has been blocked #1779
    • Fix the issue that the TiKV GC safe point is blocked due to the stagnation of TiCDC changefeed checkpoint #1756
    • Revert the update in explicit_defaults_for_timestamp which requires the SUPER privilege when replicating data to MySQL #1749

  • TiDB Lightning

    • Fix a bug that TiDB Lightning's TiDB-backend cannot load any data when autocommit is disabled