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TiDB 4.0.0 Beta.1 Release Notes

Release date: February 28, 2020

TiDB version: 4.0.0-beta.1

TiDB Ansible version: 4.0.0-beta.1

Compatibility Changes

  • TiDB

    • Modify the type of the log.enable-slow-log configuration item from integer to Boolean #14864
    • Modify the password field name to authentication_string in the mysql.user system table to make it consistent with MySQL 5.7 (This compatibility change means that you cannot roll back to earlier versions.) #14598
    • Adjust the default value of the txn-total-size-limit configuration item from 1GB to 100MB #14522
    • Support dynamically modifying or updating configuration items read from PD #14750 #14303 #14830
  • TiKV

  • PD

    • Optimize the HTTP API to make it compatible with the configuration manager #2080
  • TiDB Lightning

    • Use the default configurations specified in the document for certain items not configured in the configuration file #255
  • TiDB Ansible

    • Rename theflash to tiflash #1130
    • Optimize the default values and related configurations in TiFlash's configuration file #1138

New Features

  • TiDB

    • Support querying slow logs of any time in the SLOW_QUERY / CLUSTER_SLOW_QUERY system table #14840 #14878
    • Support SQL performance diagnosis
    • Support the Sequence function #14731 #14589 #14674 #14442 #14303 #14830
    • Support dynamically modifying or updating configuration items read from PD #14750 #14303 #14830
    • Add a 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 #14761
    • Add the Coercibility function #14739
    • Support setting TiFlash replicas in the partitioned table #14735 #14713 #14644
    • Improve the privilege check for the SLOW_QUERY table #14451
    • Support automatically write the intermediate results to the disk file if the memory is insufficient when using a SQL join #14708 #14279
    • Support checking table partitions by querying the information_schema.PARTITIONS system table #14347
    • Add the json_objectagg aggregate function #11154
    • Support logging rejected connection attempts in the audit log #14594
    • Add the max-server-connections configuration item (4096 by default) to control the number of connections to a single server #14409
    • Support the isolation read specifying multiple storage engines at the server level #14440
    • Optimize the cost model of the Apply operator and the Sort operator to improve stability #13550 #14708
  • TiKV

    • Support fetching configuration items from the status port via HTTP API #6480
    • Optimize the performance of Chunk Encoder in Coprocessor #6341
  • PD

    • Support accessing to the distribution of hotspots in the cluster through Dashboard UI #2086
    • Support capturing and displaying START_TIME and UPTIME of cluster components #2116
    • Add the information of deployment path and component version in the returned message of the member API #2130
    • Add the component sub-command in pd-ctl to modify and check the configuration of other components (experimental) #2092
  • TiDB Binlog

    • Support TLS between the components #904 #894
    • Add the kafka-client-id configuration item in Drainer to configure Kafka's client ID #902
    • Support purging the incremental backup data in Drainer #885
  • TiDB Ansible

    • Support deploying multiple Grafana/Prometheus/Alertmanagers in one cluster #1142
    • Add the metric_port configuration item (8234 by default) in TiFlash's configuration file #1145
    • Add the flash_proxy_status_port configuration item (20292 by default) in TiFlash's configuration file #1141
    • Add the TiFlash monitoring dashboard #1147 #1151

Bug Fixes

  • TiDB

    • Fix the issue that an error is reported when creating view with a column name that exceeds 64 characters #14850
    • Fix the issue that duplicate data exists in information_schema.views because the create or replace view statement is incorrectly processed #14832
    • Fix the incorrect results of BatchPointGet when plan cache is enabled #14855
    • Fix the issue that data is inserted into the wrong partitioned table after the timezone is modified #14370
    • Fix the panic occurred when rebuilding expression using the invalid name of the IsTrue function during the outer join simplification #14515
    • Fix the the incorrect privilege check for theshow binding statement #14443
  • TiKV

  • TiDB Lightning

    • Fix the bug that the web interface does not work outside the Server mode #259
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