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release-5.1.1.md

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TiDB 5.1.1 Release Notes
TiDB 5.1.1 was released on July 30, 2021. The release includes compatibility changes, feature enhancements, improvements, bug fixes, and updates to TiDB Dashboard, TiFlash, TiKV, and various tools. Notable changes include default value changes for variables, support for OIDC SSO in TiDB Dashboard, and bug fixes for data loss and panic issues.

TiDB 5.1.1 Release Notes

Release Date: July 30, 2021

TiDB version: 5.1.1

Compatibility changes

  • TiDB

    • For TiDB clusters upgrade from v4.0 to v5.1, the default value of tidb_multi_statement_mode is OFF. It is recommended to use the multi-statement feature of your client library instead. See the documentation on tidb_multi_statement_mode for details. #25751
    • Change the default value of the tidb_stmt_summary_max_stmt_count variable from 200 to 3000 #25874
    • Require the SUPER privilege to access the table_storage_stats table #26352
    • Require the SELECT privilege on mysql.user to access the information_schema.user_privileges table to show other user's privileges #26311
    • Require the CONFIG privilege to access the information_schema.cluster_hardware table #26297
    • Require the PROCESS privilege to access the information_schema.cluster_info table #26297
    • Require the PROCESS privilege to access the information_schema.cluster_load table #26297
    • Require the PROCESS privilege to access the information_schema.cluster_systeminfo table #26297
    • Require the PROCESS privilege to access the information_schema.cluster_log table #26297
    • Require the CONFIG privilege to access the information_schema.cluster_config table #26150

Feature enhancements

  • TiDB Dashboard

    • Support OIDC SSO. By setting the OIDC-compatible SSO services (such as Okta and Auth0), users can log into TiDB Dashboard without entering the SQL password. #3883

  • TiFlash

    • Support the HAVING() function in DAG requests

Improvements

  • TiDB

    • Announce the general availability (GA) of the Stale Read feature
    • Avoid allocation for paramMarker to speed up data insertion #26076
    • Support the stable result mode to make the query results more stable #25995
    • Support pushing down the built-in function json_unquote() to TiKV #26265
    • Support retrying MPP queries #26480
    • Change the LOCK record into the PUT record for the index keys using point get or batch point get for UPDATE reads #26225
    • Forbid creating views from stale queries #26200
    • Thoroughly push down the COUNT(DISTINCT) aggregation function in the MPP mode #26194
    • Check the availability of TiFlash before launching MPP queries #26192
    • Do not allow setting the read timestamp to a future time #25763
    • Print log warnings when aggregation functions cannot be pushed down in EXPLAIN statements #25737
    • Add the statements_summary_evicted table to record the evicted count information of a cluster #25587
    • Improve the MySQL compatibility of the built-in function str_to_date for the format specifiers %b/%M/%r/%T #25768

  • TiKV

    • Make the prewrite requests as idempotent as possible to reduce the chance of undetermined errors #10586
    • Prevent the risk of stack overflow when handling many expired commands #10502
    • Avoid excessive commit request retrying by not using the Stale Read request's start_ts to update max_ts #10451
    • Handle read ready and write ready separately to reduce read latency #10592
    • Reduce the impact on data import speed when the I/O rate limiting is enabled #10390
    • Improve the load balance between Raft gRPC connections #10495

  • Tools

    • TiCDC

      • Remove file sorter #2327
      • Improve the error message returned when a PD endpoint misses the certificate #1973

    • TiDB Lightning

      • Add a retry mechanism for restoring schemas #1294

    • Dumpling

      • Always split tables using _tidb_rowid when the upstream is a TiDB v3.x cluster, which helps reduce TiDB's memory usage #295
      • Reduce the frequency of accessing the database metadata to improve Dumpling's performance and stability #315

Bug fixes

  • TiDB

    • Fix the data loss issue that might occur when changing the column type with tidb_enable_amend_pessimistic_txn=on #26203
    • Fix the issue that the behavior of the last_day function is incompatible in the SQL mode #26001
    • Fix the panic issue that might occur when LIMIT is on top of window functions #25344
    • Fix the issue that committing pessimistic transactions might cause write conflict #25964
    • Fix the issue that the result of index join in correlated subqueries is wrong #25799
    • Fix a bug that the successfully committed optimistic transactions might report commit errors #10468
    • Fix the issue that an incorrect result is returned when using merge join on the SET type column #25669
    • Fix a bug that the index keys in a pessimistic transaction might be repeatedly committed #26359
    • Fix the risk of integer overflow when the optimizer is locating partitions #26227
    • Fix the issue that invalid values might be written when casting DATE to timestamp #26292
    • Fix the issue that the Coprocessor Cache metrics are not displayed on Grafana #26338
    • Fix the issue of annoying logs caused by telemetry #25760 #25785
    • Fix a bug on the query range of prefix index #26029
    • Fix the issue that concurrently truncating the same partition hangs DDL executions #26229
    • Fix the issue of duplicate ENUM items #25955
    • Fix a bug that the CTE iterator is not correctly closed #26112
    • Fix the issue that the LOAD DATA statement might abnormally import non-utf8 data #25979
    • Fix the panic issue that might occur when using the window function on the unsigned integer columns #25956
    • Fix the issue that TiDB might panic when resolving async commit locks #25778
    • Fix the issue that Stale Read is not fully compatible with the PREPARE statements #25800
    • Fix the issue that the ODBC-styled constant (for example, {d '2020-01-01'}) cannot be used as the expression #25531
    • Fix an error that occurs when running TiDB alone #25555

  • TiKV

    • Fix the issue that the duration calculation might panic on certain platforms #10569
    • Fix the issue that Load Base Split mistakenly uses the unencoded keys of batch_get_command #10542
    • Fix the issue that changing the resolved-ts.advance-ts-interval configuration dynamically cannot take effect immediately #10426
    • Fix the issue of follower metadata corruption in rare cases with more than 4 replicas #10225
    • Fix the panic issue that occurs when building a snapshot twice if encryption is enabled #9786 #10407
    • Fix the wrong tikv_raftstore_hibernated_peer_state metric #10330
    • Fix the wrong arguments type of the json_unquote() function in the coprocessor #10176
    • Fix a bug that the index keys in a pessimistic transaction might be repeatedly committed #10468
    • Fix the issue that the ReadIndex request returns stale result right after the leader is transferred #9351

  • PD

    • Fix the issue the expected scheduling cannot be generated when the conflict occurs due to multiple schedulers running at the same time #3807 #3778
    • Fix the issue that the scheduler might appear again even if the scheduler is already deleted #2572

  • TiFlash

    • Fix the potential panic issue that occurs when running table scan tasks
    • Fix a bug that TiFlash raises the error about duplicated region when handling DAQ requests
    • Fix the panic issue that occurs when the read load is heavy
    • Fix the potential panic issue that occurs when executing the DateFormat function
    • Fix the potential memory leak issue that occurs when executing MPP tasks
    • Fix the issue of unexpected results when executing the aggregation functions COUNT or COUNT DISTINCT
    • Fix a potential bug that TiFlash cannot restore data when deployed on multiple disks
    • Fix the issue that TiDB Dashboard cannot display the disk information of TiFlash correctly
    • Fix the potential panic issue that occurs when deconstructing SharedQueryBlockInputStream
    • Fix the potential panic issue that occurs when deconstructing MPPTask
    • Fix the potential issue of data inconsistency after synchronizing data via snapshot

  • Tools

    • TiCDC

      • Fix the support for the new collation feature #2301
      • Fix the issue that an unsynchronized access to a shared map at runtime might cause panic #2300
      • Fix the potential DDL loss issue that occurs when the owner crashes while executing the DDL statement #2290
      • Fix the issue of trying to resolve locks in TiDB prematurely #2188
      • Fix a bug that might cause data loss if a TiCDC node is killed immediately after a table migration #2033
      • Fix the handling logic of changefeed update on --sort-dir and --start-ts #1921

    • Backup & Restore (BR)

      • Fix the issue that the size of the data to restore is incorrectly calculated #1270
      • Fix the issue of missed DDL events that occurs when restoring from cdclog #870

    • TiDB Lightning

      • Fix the issue that TiDB fails to parse the DECIMAL type data in Parquet files #1275
      • Fix the issue of integer overflow when calculating key intervals #1291 #1290