releases: add the release notes for TiDB 2.0.1 (pingcap#469)

* releases: add the release notes for TiDB 2.0.1

* releases: update release list

* releases: update wording

* releases: address the comment

releases/2.0.1.md

@@ -0,0 +1,49 @@
+---
+title: TiDB 2.0.1 Release Notes
+category: Releases
+---
+
+# TiDB 2.0.1 Release Notes
+
+On May 16, 2018, TiDB 2.0.1 is released. Compared with TiDB 2.0.0 (GA), this release has great improvement in MySQL compatibility and system stability.
+
+## TiDB
+
+- Update the progress of `Add Index` to the DDL job information in real time
+- Add the `tidb_auto_analyze_ratio` session variable to control the threshold value of automatic statistics update
+- Fix an issue that not all residual states are cleaned up when the transaction commit fails
+- Fix a bug about adding indexes in some conditions
+- Fix the correctness related issue when DDL modifies surface operations in some concurrent scenarios
+- Fix a bug that the result of `LIMIT` is incorrect in some conditions
+- Fix a capitalization issue of the `ADMIN CHECK INDEX` statement to make its index name case insensitive
+- Fix a compatibility issue of the `UNION` statement
+- Fix a compatibility issue when inserting data of `TIME` type
+- Fix a goroutine leak issue caused by `copIteratorTaskSender` in some conditions
+- Add an option for TiDB to control the behaviour of Binlog failure
+- Refactor the `Coprocessor` slow log to distinguish between the scenario of tasks with long processing time and long waiting time
+- Log nothing when meeting MySQL protocol handshake error, to avoid too many logs caused by the load balancer Keep Alive mechanism
+- Refine the “Out of range value for column” error message
+- Fix a bug when there is a subquery in an `Update` statement
+- Change the behaviour of handling `SIGTERM`, and do not wait for all queries to terminate anymore
+
+## PD
+
+- Add the `Scatter Range` scheduler to balance Regions with the specified key range
+- Optimize the scheduling of Merge Region to prevent the newly split Region from being merged
+- Add Learner related metrics
+- Fix the issue that the scheduler is mistakenly deleted after restart
+- Fix the error that occurs when parsing the configuration file
+- Fix the issue that the etcd leader and the PD leader are not synchronized
+- Fix the issue that Learner still appears after it is closed
+- Fix the issue that Regions fail to load because the packet size is too large
+
+## TiKV
+
+- Fix the issue that `SELECT FOR UPDATE` prevents others from reading
+- Optimize the slow query log
+- Reduce the number of `thread_yield` calls
+- Fix the bug that raftstore is accidentally blocked when generating the snapshot
+- Fix the issue that Learner cannot be successfully elected in special conditions
+- Fix the issue that split might cause dirty read in extreme conditions
+- Correct the default value of the read thread pool configuration
+- Speed up Delete Range

releases/rn.md

@@ -5,6 +5,7 @@ category: release
 
 # TiDB Release Notes
 
+  - [2.0.1](2.0.1.md)
   - [2.0](2.0ga.md)
   - [2.0 RC5](2rc5.md)
   - [2.0 RC4](2rc4.md)