releases, readme: add the release notes for 2.1 RC1

Author: CaitinChen

README.md

@@ -130,6 +130,7 @@
 - [Frequently Asked Questions (FAQ)](FAQ.md)
 - [TiDB Best Practices](https://pingcap.github.io/blog/2017/07/24/tidbbestpractice/)
 + [Releases](releases/rn.md)
+  - [2.1 RC1](releases/2.1rc1.md)
   - [2.0.6](releases/206.md)
   - [2.0.5](releases/205.md)
   - [2.1 Beta](releases/21beta.md)

releases/2.1rc1.md

@@ -0,0 +1,155 @@
+---
+title: TiDB 2.1 RC1 Release Notes
+category: Releases
+---
+
+# TiDB 2.1 RC1 Release Notes
+
+On August 24, 2018, TiDB 2.1 RC1 is released! Compared with TiDB 2.1 Beta, this release has great improvement in stability, SQL optimizer, statistics information, and execution engine.
+
+## TiDB
+
+- SQL Optimizer
+    - Fix the issue that a wrong result is returned after the correlated subquery is decorrelated in some cases [#6972](https://github.com/pingcap/tidb/pull/6972)
+    - Optimize the output result of `Explain` [#7011](https://github.com/pingcap/tidb/pull/7011)[#7041](https://github.com/pingcap/tidb/pull/7041)
+    - Optimize the choosing strategy of the outer table for `IndexJoin` [#7019](https://github.com/pingcap/tidb/pull/7019)
+    - Remove the Plan Cache of the non-`PREPARE` statement [#7040](https://github.com/pingcap/tidb/pull/7040)
+    - Fix the issue that the `INSERT` statement is not parsed and executed correctly in some cases [#7068](https://github.com/pingcap/tidb/pull/7068)
+    - Fix the issue that the `IndexJoin` result is not correct in some cases [#7150](https://github.com/pingcap/tidb/pull/7150)
+    - Fix the issue that the `NULL` value cannot be found using the unique index in some cases [#7163](https://github.com/pingcap/tidb/pull/7163)
+    - Fix the range computing issue of the prefix index in UTF-8 [#7194](https://github.com/pingcap/tidb/pull/7194)
+    - Fix the issue that result is not correct caused by eliminating the `Project` operator in some cases [#7257](https://github.com/pingcap/tidb/pull/7257)
+    - Fix the issue that `USE INDEX(`PRIMARY`)` cannot be used when the primary key is an integer [#7316](https://github.com/pingcap/tidb/pull/7316)
+    - Fix the issue that the index range cannot be computed using the correlated column in some cases [#7357](https://github.com/pingcap/tidb/pull/7357)
+- SQL Execution Engine
+    - Fix the issue that the daylight saving time is not computed correctly in some cases [#6823](https://github.com/pingcap/tidb/pull/6823)
+    - Refactor the aggregation function framework to improve the execution efficiency of the `Stream` and `Hash` aggregation operators [#6852](https://github.com/pingcap/tidb/pull/6852)
+    - Fix the issue that the `Hash` aggregation operator cannot exit normally in some cases [#6982](https://github.com/pingcap/tidb/pull/6982)
+    - Fix the issue that `BIT_AND`/`BIT_OR`/`BIT_XOR` does not handle the non-integer data correctly [#6994](https://github.com/pingcap/tidb/pull/6994)
+    - Optimize the execution speed of the `REPLACE INTO` statement and increase the performance nearly 10 times [#7027](https://github.com/pingcap/tidb/pull/7027)
+    - Optimize the memory usage of time type data and decrease the memory usage of the time type data by fifty percent [#7043](https://github.com/pingcap/tidb/pull/7043)
+    - Fix the issue that the returned result is mixed with signed and unsigned integers in the `UNION` statement is not compatible with MySQL [#7112](https://github.com/pingcap/tidb/pull/7112)
+    - Fix the panic issue caused by the too much memory applied by `LPAD`/`RPAD`/`TO_BASE64`/`FROM_BASE64`/`REPEAT` [#7171](https://github.com/pingcap/tidb/pull/7171) [#7266](https://github.com/pingcap/tidb/pull/7266) [#7409](https://github.com/pingcap/tidb/pull/7409) [#7431](https://github.com/pingcap/tidb/pull/7431)
+    - Fix the incorrect result when `MergeJoin`/`IndexJoin` handles the `NULL` value [#7255](https://github.com/pingcap/tidb/pull/7255)
+    - Fix the incorrect result of `Outer Join` in some cases [#7288](https://github.com/pingcap/tidb/pull/7288)
+    - Improve the error message of `Data Truncated` to facilitate locating the wrong data and the corresponding field in the table [#7401](https://github.com/pingcap/tidb/pull/7401)
+    - Fix the incorrect result for `decimal` in some cases [#7001](https://github.com/pingcap/tidb/pull/7001) [#7113](https://github.com/pingcap/tidb/pull/7113) [#7202](https://github.com/pingcap/tidb/pull/7202) [#7208](https://github.com/pingcap/tidb/pull/7208)
+    - Optimize the point select performance [#6937](https://github.com/pingcap/tidb/pull/6937)
+    - Prohibit the isolation level of `Read Commited` to avoid the underlying problem [#7211](https://github.com/pingcap/tidb/pull/7211)
+    - Fix the incorrect result of `LTRIM`/`RTRIM`/`TRIM` in some cases [#7291](https://github.com/pingcap/tidb/pull/7291)
+    - Fix the issue that the `MaxOneRow` operator cannot guarantee that the returned result does not exceed one row [#7375](https://github.com/pingcap/tidb/pull/7375)
+    - Divide the Coprocessor requests with too many ranges [#7454](https://github.com/pingcap/tidb/pull/7454)
+- Statistics
+    - Optimize the mechanism of statistics dynamic collection [#6796](https://github.com/pingcap/tidb/pull/6796)
+    - Fix the issue that `Auto Analyze` does not work when data is updated frequently [#7022](https://github.com/pingcap/tidb/pull/7022)
+    - Decrease the Write conflicts during the statistics dynamic update process [#7124](https://github.com/pingcap/tidb/pull/7124)
+    - Optimize the cost estimation when the statistics is incorrect [#7175](https://github.com/pingcap/tidb/pull/7175)
+    - Optimize the `AccessPath` cost estimation strategy [#7233](https://github.com/pingcap/tidb/pull/7233)
+- Server
+    - Fix the bug in loading privilege information [#6976](https://github.com/pingcap/tidb/pull/6976)
+    - Fix the issue that the `Kill` command is too strict with privilege check [#6954](https://github.com/pingcap/tidb/pull/6954)
+    - Fix the issue of removing some binary numeric types [#6922](https://github.com/pingcap/tidb/pull/6922)
+    - Shorten the output log [#7029](https://github.com/pingcap/tidb/pull/7029)
+    - Handle the `mismatchClusterID` issue [#7053](https://github.com/pingcap/tidb/pull/7053)
+    - Add the `advertise-address` configuration item [#7078](https://github.com/pingcap/tidb/pull/7078)
+    - Add the `GrpcKeepAlive` option [#7100](https://github.com/pingcap/tidb/pull/7100)
+    - Add the connection or `Token` time monitor [#7110](https://github.com/pingcap/tidb/pull/7110)
+    - Optimize the data decoding performance [#7149](https://github.com/pingcap/tidb/pull/7149)
+    - Add the `PROCESSLIST` table in `INFORMMATION_SCHEMA` [#7236](https://github.com/pingcap/tidb/pull/7236)
+    - Fix the order issue when multiple rules are hit in verifying the privilege [#7211](https://github.com/pingcap/tidb/pull/7211)
+    - Change some default values of encoding related system variables to UTF-8 [#7198](https://github.com/pingcap/tidb/pull/7198)
+    - Make the slow query log show more detailed information [#7302](https://github.com/pingcap/tidb/pull/7302)
+    - Support registering tidb-server related information in PD and obtaining this information by HTTP API [#7082](https://github.com/pingcap/tidb/pull/7082)
+- Compatibility
+    - Support Session variables `warning_count` and `error_count` [#6945](https://github.com/pingcap/tidb/pull/6945)
+    - Add `Scope` check when reading the system variables [#6958](https://github.com/pingcap/tidb/pull/6958)
+    - Support the `MAX_EXECUTION_TIME` syntax [#7012](https://github.com/pingcap/tidb/pull/7012)
+    - Support more statements of the `SET` syntax [#7020](https://github.com/pingcap/tidb/pull/7020)
+    - Add validity check when setting system variables [#7117](https://github.com/pingcap/tidb/pull/7117)
+    - Add the verification of the number of `PlaceHolder`s in the `Prepare` statement [#7162](https://github.com/pingcap/tidb/pull/7162)
+    - Support `set character_set_results = null` [#7353](https://github.com/pingcap/tidb/pull/7353)
+    - Support the `flush status` syntax [#7369](https://github.com/pingcap/tidb/pull/7369)
+    - Fix the column size of `SET` and  `ENUM` types in `information_schema` [#7347](https://github.com/pingcap/tidb/pull/7347)
+    - Support the `NATIONAL CHARACTER` syntax of statements for creating a table [#7378](https://github.com/pingcap/tidb/pull/7378)
+    - Support the `CHARACTER SET` syntax in the `LOAD DATA` statement  [#7391](https://github.com/pingcap/tidb/pull/7391)
+    - Fix the column information of the `SET` and `ENUM` types [#7417](https://github.com/pingcap/tidb/pull/7417)
+    - Support the `IDENTIFIED WITH` syntax in the `CREATE USER` statement  [#7402](https://github.com/pingcap/tidb/pull/7402)
+    - Fix the precision losing issue during `TIMESTAMP` computing process [#7418](https://github.com/pingcap/tidb/pull/7418)
+    - Support the validity verification of more `SYSTEM` variables [#7196](https://github.com/pingcap/tidb/pull/7196)
+    - Fix the incorrect result when the `CHAR_LENGTH` function computes the binary string [#7410](https://github.com/pingcap/tidb/pull/7410)
+    - Fix the incorrect `CONCAT` result in a statement involving `GROUP BY` [#7448](https://github.com/pingcap/tidb/pull/7448)
+    - Fix the imprecise type length issue when casting the `DECIMAL` type to the `STRING` type [#7451](https://github.com/pingcap/tidb/pull/7451)
+- DML
+    - Fix the stability issue of the `Load Data` statement [#6927](https://github.com/pingcap/tidb/pull/6927)
+    - Fix the memory usage issue when performing some `Batch` operations [#7086](https://github.com/pingcap/tidb/pull/7086)
+    - Improve the performance of the `Replace Into` statement [#7027](https://github.com/pingcap/tidb/pull/7027)
+    - Fix the inconsistent precision issue when writing `CURRENT_TIMESTAMP` [#7355](https://github.com/pingcap/tidb/pull/7355)
+- DDL
+    - Improve the method of DDL judging whether `Schema` is synchronized to avoid misjudgement in some cases [#7319](https://github.com/pingcap/tidb/pull/7319)
+    - Fix the `SHOW CREATE TABLE` result in adding index process [#6993](https://github.com/pingcap/tidb/pull/6993)
+    - Allow the default value of `text`/`blob`/`json` to be NULL in non-restrict `sql-mode` [#7230](https://github.com/pingcap/tidb/pull/7230)
+    - Fix the `ADD INDEX` issue in some cases [#7142](https://github.com/pingcap/tidb/pull/7142)
+    - Increase the speed of adding `UNIQUE-KEY` index operation largely [#7132](https://github.com/pingcap/tidb/pull/7132)
+    - Fix the truncating issue of the prefix index in UTF-8 character set [#7109](https://github.com/pingcap/tidb/pull/7109)
+    - Add the environment variable  `tidb_ddl_reorg_priority` to control the priority of the `add-index` operation [#7116](https://github.com/pingcap/tidb/pull/7116)
+    - Fix the display issue of `AUTO-INCREMENT` in `information_schema.tables` [#7037](https://github.com/pingcap/tidb/pull/7037)
+    - Support the `admin show ddl jobs <number>` command and support output specified number of DDL jobs [#7028](https://github.com/pingcap/tidb/pull/7028)
+    - Support parallel DDL job execution [#6955](https://github.com/pingcap/tidb/pull/6955)
+- [Table Partition](https://github.com/pingcap/tidb/projects/6) (Experimental)
+    - Support top level partition
+    - Support `Range Partition`
+
+## PD
+
+- Features
+    - Introduce the version control mechanism and support rolling update of the cluster with compatibility
+    - Enable the `region merge` feature
+    - Support the `GetPrevRegion` interface
+    - Support splitting Regions in batch
+    - Support storing the GC safepoint
+- Improvements
+    - Optimize the issue that TSO allocation is affected by the system clock going backwards
+    - Optimize the performance of handling Region heartbeats
+    - Optimize the Region tree performance
+    - Optimize the performance of computing hotspot statistics
+    - Optimize returning the error code of API interface
+    - Add options of controlling scheduling strategies
+    - Prohibit using special characters in `label`
+    - Improve the scheduling simulator
+    - Support splitting Regions using statistics in pd-ctl
+    - Support formatting JSON output by calling `jq` in pd-ctl
+    - Add metrics about etcd Raft state machine
+- Bug fixes
+    - Fix the issue that the namespace is not reloaded after switching Leader
+    - Fix the issue that namespace scheduling exceeds the schedule limit
+    - Fix the issue that hotspot scheduling exceeds the schedule limit
+    - Fix the issue that wrong logs are output when the PD client closes
+    - Fix the wrong statistics of Region heartbeat latency
+
+## TiKV
+
+- Features
+    - Support `batch split` to avoid too large Regions caused by the Write operation on hot Regions
+    - Support splitting Regions based on the number of rows to improve the index scan efficiency
+- Performance
+    - Use `LocalReader` to separate the Read operation from the raftstore thread to lower the Read latency
+    - Refactor the MVCC framework, optimize the memory usage and improve the scan Read performance
+    - Support splitting Regions based on statistics estimation to reduce the I/O usage
+    - Optimize the issue that the Read performance is affected by continuous Write operations on the rollback record
+    - Reduce the memory usage of pushdown aggregation computing
+- Improvements
+    - Add the pushdown support for a large number of built-in functions and better charset support
+    - Optimize the GC workflow, improve the GC speed and decrease the impact of GC on the system
+    - Enable `prevote` to speed up service recovery when the network is abnormal
+    - Add the related configuration items of RocksDB log files
+    - Adjust the default configuration of `scheduler_latch`
+    - Support setting whether to compact the data in the bottom layer of RocksDB when using tikv-ctl to compact data manually
+    - Add the check for environment variables when starting TiKV
+    - Support dynamically configuring the `dynamic_level_bytes` parameter based on the existing data
+    - Support customizing the log format
+    - Integrate tikv-fail in tikv-ctl
+    - Add I/O metrics of threads
+- Bug fixes
+    - Fix decimal related issues
+    - Fix the issue that `gRPC max_send_message_len` is set mistakenly
+    - Fix the issue caused by misconfiguration of `region_size`

releases/rn.md

@@ -5,6 +5,7 @@ category: release
 
 # TiDB Release Notes
 
+  - [2.1 RC1](releases/2.1rc1.md)
   - [2.0.6](206.md)
   - [2.0.5](205.md)
   - [2.1 Beta](21beta.md)