TiDB 2.1 RC3 Release Notes

On September 29, 2018, TiDB 2.1 RC3 is released. Compared with TiDB 2.1 RC2, this release has great improvement in stability, compatibility, SQL optimizer, and execution engine.

TiDB

• SQL Optimizer
  • Fix the incorrect result issue when a statement contains embedded LEFT OUTER JOIN #7689
  • Enhance the optimization rule of predicate pushdown on the JOIN statement #7645
  • Fix the optimization rule of predicate pushdown for the UnionScan operator #7695
  • Fix the issue that the unique key property of the Union operator is not correctly set #7680
  • Enhance the optimization rule of constant folding #7696
  • Optimize the data source in which the filter is null after propagation to table dual #7756
• SQL Execution Engine
  • Optimize the performance of read requests in a transaction #7717
  • Optimize the cost of allocating Chunk memory in some executors #7540
  • Fix the "index out of range" panic caused by the columns where point queries get all NULL values #7790
• Server
  • Fix the issue that the memory quota in the configuration file does not take effect #7729
  • Add the tidb_force_priority system variable to set the execution priority for each statement #7694
  • Support using the admin show slow statement to obtain the slow query log #7785
• Compatibility
  • Fix the issue that the result of charset/collation is incorrect in information_schema.schemata #7751
  • Fix the issue that the value of the hostname system variable is empty #7750
• Expressions
  • Support the init_vecter argument in the AES_ENCRYPT/AES_DECRYPT built-in function #7425
  • Fix the issue that the result of Format is incorrect in some expressions #7770
  • Support the JSON_LENGTH built-in function #7739
  • Fix the incorrect result issue when casting the unsigned integer type to the decimal type #7792
• DML
  • Fix the issue that the result of the INSERT … ON DUPLICATE KEY UPDATE statement is incorrect while updating the unique key #7675
• DDL
  • Fix the issue that the index value is not converted between time zones when you create a new index on a new column of the timestamp type #7724
  • Support appending new values for the enum type #7767
  • Support creating an etcd session quickly, which improves the cluster availability after network isolation #7774

PD

• New feature
  • Add the API to get the Region list by size in reverse order #1254
• Improvement
  • Return more detailed information in the Region API #1252
• Bug fix
  • Fix the issue that adjacent-region-scheduler might lead to a crash after PD switches the leader #1250

TiKV

• Performance
  • Optimize the concurrency for coprocessor requests #3515
• New features
  • Add the support for Log functions #3603
  • Add the support for the sha1 function #3612
  • Add the support for the truncate_int function #3532
  • Add the support for the year function #3622
  • Add the support for the truncate_real function #3633
• Bug fixes
  • Fix the reporting error behavior related to time functions #3487, #3615
  • Fix the issue that the time parsed from string is inconsistent with that in TiDB #3589