TiDB 3.0.3 Release Notes

Release date: August 29, 2019

TiDB version: 3.0.3

TiDB Ansible version: 3.0.3

TiDB

• SQL Optimizer
  • Add the opt_rule_blacklist table to disable logic optimization rules such as aggregation_eliminate and column_prune #11658
  • Fix the issue that incorrect results might be returned for Index Join when the join key uses a prefix index or an unsigned index column that is equal to a negative value #11759
  • Fix the issue that " or \ in the SELECT statements of create … binding ... might result in parsing errors #11726
• SQL Execution Engine
  • Fix the issue that type errors in the return value might occur when the Quote function handles a null value #11619
  • Fix the issue that incorrect results for ifnull might be returned when Max/Min is used for type inferring with NotNullFlag retained #11641
  • Fix the potential error that occurs when comparing bit type data in string form #11660
  • Decrease the concurrency for data that requires sequential read to lower the possibility of OOM #11679
  • Fix the issue that incorrect type inferring might be caused when multiple parameters are unsigned for some built-in functions (for example, if and coalesce) #11621
  • Fix the incompatibility with MySQL when the Div function handles unsigned decimal types #11813
  • Fix the issue that panic might occur when executing SQL statements that modify the status of Pump/Drainer #11827
  • Fix the issue that panic might occur for select ... for update when Autocommit = 1 and there is no begin statement #11736
  • Fix the permission check error that might occur when the set default role statement is executed #11777
  • Fix the permission check error that might occur when create user or drop user is executed #11814
  • Fix the issue that the select ... for update statement might auto retry when it is constructed into the PointGetExecutor function #11718
  • Fix the boundary error that might occur when the Window function handles partition #11825
  • Fix the issue that the time function hits EOF errors when handling an incorrectly formatted argument #11893
  • Fix the issue that the Window function does not check the passed-in parameters #11705
  • Fix the issue that the plan result viewed via Explain is inconsistent with the actually executed plan #11186
  • Fix the issue that duplicate memory referenced by the Window function might result in a crash or incorrect results #11823
  • Update the incorrect information in the Succ field in the slow log #11887
• Server
  • Rename the tidb_back_off_wexight variable to tidb_backoff_weight #11665
  • Update the minimum TiKV version compatible with the current TiDB to v3.0.0 #11618
  • Support make testSuite to ensure the suites in the test are correctly used #11685
• DDL
  • Skip the execution of unsupported partition-related DDL statements, including statements that modify the partition type while deleting multiple partitions #11373
  • Disallow a Generated Column to be placed before its dependent columns #11686
  • Modify the default values of tidb_ddl_reorg_worker_cnt and tidb_ddl_reorg_batch_size #11874
• Monitor
  • Add new backoff monitoring types to record duration for each backoff type; add more backoff metrics to cover previously uncounted types such as commit backoff #11728

TiKV

• Fix the issue that ReadIndex might fail to respond to requests because of duplicate context #5256
• Fix potential scheduling jitters caused by premature PutStore #5277
• Fix incorrect timestamps reported from Region heartbeats #5296
• Reduce the size of core dump by excluding the shared block cache from it #5322
• Fix potential TiKV panics during region merge #5291
• Speed up leader change check for the dead lock detector #5317
• Support using grpc env to create deadlock clients #5346
• Add config-check to check whether the configuration is correct #5349
• Fix the issue that ReadIndex does not return anything when there is no leader #5351

PD

• Return success message for pdctl #1685

Tools

• TiDB Binlog
  • Modify the default value of defaultBinlogItemCount in Drainer from 65536 to 512 to reduce the chance of OOM on Drainer startup #721
  • Optimize the offline logic for pump server to avoid potential offline congestions #701
• TiDB Lightning:
  • Skip the system databases mysql, information_schema, performance_schema, and sys by default when importing #225

TiDB Ansible

• Optimize PD operations for rolling update to improve stability #894
• Remove the Grafana Collector components that are not supported by the current Grafana version #892
• Update TiKV alerting rules #898
• Fix the issue that the generated TiKV configuration misses the pessimistic-txn parameter #911
• Update Spark to V2.4.3, and update TiSpark to V2.1.4 that is compatible with Spark V2.4.3 #913, #918