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release-3.0.9.md

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title TiDB 3.0.9 Release Notes
aliases
/docs/dev/releases/release-3.0.9/
/docs/dev/releases/3.0.9/
summary TiDB 3.0.9 was released on January 14, 2020. It includes fixes for known issues and new features. Some improvements were made to Executor, Server, DDL, Planner, TiKV, PD, Tools, and TiDB Ansible. Notable changes include support for system variables, monitoring metrics, and optimizations for transaction execution latency. Additionally, support for using backlash in the location label name and automatically creating directories for TiDB Lightning deployment was added.

TiDB 3.0.9 Release Notes

Release date: January 14, 2020

TiDB version: 3.0.9

TiDB Ansible version: 3.0.9

Warning:

Some known issues are found in this version, and these issues are fixed in new versions. It is recommended that you use the latest 3.0.x version.

TiDB

  • Executor
    • Fix the incorrect result when the aggregate function is applied to the ENUM column and the collection column #14364
  • Server
    • Support the auto_increment_increment and auto_increment_offset system variables #14396
    • Add the tidb_tikvclient_ttl_lifetime_reach_total monitoring metric to monitor the number of pessimistic transactions with a TTL of 10 minutes #14300
    • Output the SQL information in the log when the SQL query causes a panic during its execution #14322
    • Add the plan and plan_digest fields in the statement summary table to record the plan that is being executed and the plan signature #14285
    • Adjust the default value of the stmt-summary.max-stmt-count configuration item from 100 to 200 #14285
    • Add the plan_digest field in the slow query table to record the plan signature #14292
  • DDL
    • Fix the issue that the results of anonymous indexes created using alter table ... add index on the primary column is inconsistent with MySQL #14310
    • Fix the issue that VIEWs are mistakenly dropped by the drop table syntax #14052
  • Planner
    • Optimize the performance of statements such as select max(a), min(a) from t. If an index exists in the a column, the statement is optimized to select * from (select a from t order by a desc limit 1) as t1, (select a from t order by a limit 1) as t2 to avoid full table scan #14410

TiKV

  • Raftstore
    • Speed up the configuration change to speed up the Region scattering #6421
  • Transaction
    • Add the tikv_lock_manager_waiter_lifetime_duration, tikv_lock_manager_detect_duration, and tikv_lock_manager_detect_duration monitoring metrics to monitor waiters' lifetime, the time cost of detecting deadlocks, and the status of Wait table #6392
    • Optimize the following configuration items to reduce transaction execution latency caused by changing Region leader or the leader of deadlock detector in extreme situations #6429
      • Change the default value of wait-for-lock-time from 3s to 1s
      • Change the default value of wake-up-delay-duration from 100ms to 20ms
    • Fix the issue that the leader of the deadlock detector might be incorrect during the Region Merge process #6431

PD

  • Support using backlash / in the location label name #2083
  • Fix the incorrect statistics because the tombstone store is mistakenly included by the label counter #2067

Tools

  • TiDB Binlog
    • Add the unique key information in the binlog protocol output by Drainer #862
    • Support using the encrypted password for database connection for Drainer #868

TiDB Ansible

  • Support automatically creating directories to optimize the deployment of TiDB Lightning #1105