You are viewing the documentation of an older version of the TiDB database (TiDB v3.1).

It is recommended that you use the latest LTS version of the TiDB database.

TiDB 3.1 RC Release Notes

Release date: April 2, 2020

TiDB version: 3.1.0-rc

TiDB Ansible version: 3.1.0-rc


Some known issues are found in this version, and these issues are fixed in new versions. It is recommended that you use the latest 3.1.x version.

New Features

  • TiDB

    • Use the binary search to re-implement partition pruning for better performance #15678
    • Support using the RECOVER syntax to recover the truncated table #15460
    • Add the AUTO_RANDOM ID cache for retrying statements and recovering tables #15393
    • Support restoring the state of the AUTO_RANDOM ID allocator using the recover table statement #15393
    • Support YEAR, MONTH, and TO_DAY functions as the partitioning keys of the Hash partitioned table #15619
    • Add the table ID to the schema-change related tables only when keys need to be locked in the SELECT... FOR UPDATE statement #15708
    • Add the feature of automatically reading data from different roles according to the load balancing policy and add the leader-and-follower system variable to enable this feature #15721
    • Support dynamically updating the TLS certificate every time TiDB establishes a new connection to update expired client certificate without restarting the RPC client side #15163
    • Upgrade PD Client to support loading the latest certificate every time TiDB establishes a new connection #15425
    • Forcibly use the HTTPS protocol with the configured TLS certificates between a TiDB server and a PD server, or between two TiDB servers when cluster-ssl-* is configured #15430
    • Add the MySQL-compatible --require-secure-transport startup option to force the client to enable TLS authentication during the configuration #15442
    • Add the cluster-verify-cn configuration item. After configuration, the status service can only be used when with the corresponding CN certificate #15137
  • TiKV

    • Support backing up data with the Raw KV API #7051
    • Support TLS authentication for the status server #7142
    • Support TLS authentication for the KV server #7305
    • Optimize the time to hold locks to improve the performance of backup #7202
  • PD

    • Support scheduling learner using shuffle-region-scheduler #2235
    • Add commands in pd-ctl to configure Placement Rules #2306
  • Tools

    • TiDB Binlog

      • Support TLS authentication between the components #931 #937 #939
      • Add the kafka-client-id configuration item in Drainer to configure Kafka's client ID #929
    • TiDB Lightning

      • Optimize the performance of TiDB Lightning #281 #275
      • Support TLS authentication for TiDB Lightning #270
    • Backup & Restore (BR)

      • Optimize the log output #189
  • TiDB Ansible

    • Optimize the way the TiFlash data directories are created #1242
    • Add the Write Amplification monitoring item in TiFlash #1234
    • Optimize the error message of failed preflight checks when CPU epollexclusive is unavailable #1243

Bug Fixes

  • TiDB

    • Fix the information schema error caused by frequently updating the TiFlash replica #14884
    • Fix the issue that last_insert_id is incorrectly generated when applying AUTO_RANDOM #15149
    • Fix the issue that updating the status of TiFlash replica might cause the DDL operation to get stuck #15161
    • Forbid Aggregation pushdown and TopN pushdown when there are predicates that can not be pushed down #15141
    • Forbid the nested view creation #15440
    • Fix the error occurred when executing SELECT CURRENT_ROLE() after SET ROLE ALL #15570
    • Fix the failure to identify the view name when executing the select view_name.col_name from view_name statement #15573
    • Fix the issue that an error might occur when pre-processing DDL statements during the write of binlog information #15444
    • Fix the panic occurred when accessing both views and partitioned tables #15560
    • Fix the error occurred when executing the VALUES function with the update duplicate key statement that contains the bit(n) data type #15487
    • Fix the issue that the specified maximum execution time fails to take effect in some scenarios #15616
    • Fix the issue that whether the current ReadEngine contains TiKV server is not checked when generating the execution plan using Index Scan #15773
  • TiKV

    • Fix the issue of conflict check failure or data index inconsistency caused by inserting an existing key into a transaction and then deleting it immediately when disabling the consistency check parameter #7112
    • Fix the calculation error when TopN compares unsigned integers #7199
    • Introduce a flow control mechanism in Raftstore to solve the problem that without flow control, it might cause slow log tracking and cause the cluster to be stuck; and the problem that the large transaction size might cause the frequent reconnection among TiKV servers #7087 #7078
    • Fix the issue that pending read requests sent to replicas might be permanently blocked #6543
    • Fix the issue that replica read might be blocked by applying snapshots #7249
    • Fix the issue that transferring leader might cause TiKV to panic #7240
    • Fix the issue that all SST files are filled with zeroes when backing up data to S3 #6967
    • Fix the issue that the size of SST file is not recorded during backup, resulting in many empty Regions after restoration #6983
    • Support AWS IAM web identity for backup #7297
  • PD

    • Fix the issue of incorrect Region information caused by data race when PD processes Region heartbeats #2234
    • Fix the issue that random-merge-scheduler fails to follow location labels and Placement Rules #2212
    • Fix the issue that a placement rule is overwritten by another placement rule with the same startKey and endKey #2222
    • Fix the issue that the version number of API is inconsistent with that of PD server #2192
  • Tools

    • TiDB Lightning

      • Fix the bug that the & character is replaced by the EOF character in TiDB backend #283
    • Backup & Restore (BR)

      • Fix the issue that BR cannot restore the TiFlash cluster data #194
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