TiDB 2.0 RC1 Release Notes

[zhangyanqing]

On March 9, 2018, TiDB 2.0 RC1 is released. This release has great improvement in MySQL compatibility, SQL optimization and stability.

TiDB:

• Support limiting the memory usage by a single SQL statement, to reduce the risk of OOM
• Support pushing the Stream Aggregate operator down to TiKV
• Support validating the configuration file
• Support obtaining the information of TiDB configuration through HTTP API
• Compatible with more MySQL syntax in Parser
• Improve the compatibility with Navicat
• Improve the optimizer and extract common expressions with multiple OR conditions, to choose better query plan
• Improve the optimizer and convert subqueries to Join operators in more scenarios, to choose better query plan
• Resolve Lock in the Batch mode to increase the garbage collection speed
• Fix the length of Boolean field to improve compatibility
• Optimize the Add Index operation and give lower priority to all write and read operations, to reduce the impact on online business

PD:

• Optimize the logic of code used to check the Region status to improve performance
• Optimize the output of log information in abnormal conditions to facilitate debugging
• Fix the monitor statistics that the disk space of TiKV nodes is not enough
• Fix the wrong reporting issue of the health interface when TLS is enabled
• Fix the issue that concurrent addition of replicas might exceed the threshold value of configuration, to improve stability

TiKV:

• Fix the issue that gRPC call is not cancelled when PD leaders switch
• Protect important configuration which cannot be changed after initial configuration
• Add gRPC APIs used to obtain metrics
• Check whether SSD is used when you start the cluster
• Optimize the read performance using ReadPool, and improve the performance by 30% in the raw get test
• Improve metrics and optimize the usage of metrics