CHANGELOG: add 2.0.0-rc release notes (#913)

CHANGELOG.md

@@ -2,6 +2,70 @@
 
 All notable changes to this project will be documented in this file.
 
+## [2.0.0-rc] 2020-08-21
+
+### Improvements
+
+- Support high availability for data migration tasks
+- Add an optimistic mode for sharding DDL statements
+- Add the `handle-error` command to handle errors during DDL incremental replication
+- Add a `workaround` field in the error returned by `query-status` to suggest the error handling method
+- Improve the monitoring dashboards and alert rules
+- Replace Mydumper with Dumpling as the full export unit
+- Support the GTID mode when performing incremental replication to the downstream
+- Support TLS connections between upstream and downstream databases, and between DM components
+- Support the incremental replication scenarios where the table of the downstream has more columns than that of the upstream
+- Add a `--remove-meta` option to the `start-task` command to clean up metadata related to data migration tasks
+- Support dropping columns with single-column indices
+- Support automatically cleaning up temporary files after a successful full import
+- Support checking whether the table to be migrated has a primary key or a unique key before starting a migration task
+- Support connectivity check between dmctl and DM-master while starting dmctl
+- Support connectivity check for downstream TiDB during the execution of `start-task`/`check-task`
+- Support replacing task names with task configuration files for some commands such as `pause-task`
+- Support logs in `json` format for DM-master and DM-worker components
+- Remove the call stack information and redundant fields in the error message returned by `query-status`
+- Improve the binlog position information of the upstream database returned by `query-status`
+- Improve the processing of `auto resume` when an error is encountered during the full export
+
+### Bug fixes
+
+- Fix the issue of goroutine leak after executing `stop-task`
+- Fix the issue that the task might not be paused after executing `pause-task`
+- Fix the issue that the checkpoint might not be saved correctly in the initial stage of incremental replication
+- Fix the issue that the `BIT` data type is incorrectly handled during incremental replication
+
+### Action required
+
+- When upgrading from a previous version, note that you must upgrade all DM components (dmctl/DM-master/DM-worker) together
+
+### Detailed Bug Fixes and Changes
+
+- Support high availability for data migration tasks [#473](https://github.com/pingcap/dm/pull/473)
+- Add an optimistic mode for sharding DDL statements [#568](https://github.com/pingcap/dm/pull/568)
+- Add the `handle-error` command to handle errors during DDL incremental replication [#850](https://github.com/pingcap/dm/pull/850)
+- Add a `workaround` field in the error returned by `query-status` to suggest the error handling method [#753](https://github.com/pingcap/dm/pull/753)
+- Improve the monitoring dashboards and alert rules [#853](https://github.com/pingcap/dm/pull/853)
+- Replace Mydumper with Dumpling as the full export unit [#540](https://github.com/pingcap/dm/pull/540)
+- Support the GTID mode when performing incremental replication to the downstream [#521](https://github.com/pingcap/dm/pull/521)
+- Support TLS connections between upstream and downstream databases, and between DM components [#569](https://github.com/pingcap/dm/pull/569)
+- Support the incremental replication scenarios where the table of the downstream has more columns than that of the upstream [#379](https://github.com/pingcap/dm/pull/379)
+- Add a `--remove-meta` option to the `start-task` command to clean up metadata related to data migration tasks [#651](https://github.com/pingcap/dm/pull/651)
+- Support dropping columns with single-column indices [#801](https://github.com/pingcap/dm/pull/801)
+- Support automatically cleaning up temporary files after a successful full import [#770](https://github.com/pingcap/dm/pull/770)
+- Support checking whether the table to be migrated has a primary key or a unique key before starting a migration task [#870](https://github.com/pingcap/dm/pull/870)
+- Support connectivity check between dmctl and DM-master while starting dmctl [#786](https://github.com/pingcap/dm/pull/786)
+- Support connectivity check for downstream TiDB during the execution of `start-task`/`check-task` [#769](https://github.com/pingcap/dm/pull/769) 
+- Support replacing task names with task configuration files for some commands such as `pause-task` [#854](https://github.com/pingcap/dm/pull/854)
+- Support logs in `json` format for DM-master and DM-worker components [#808](https://github.com/pingcap/dm/pull/808)
+- Remove the call stack information in the error message returned by `query-status` [#746](https://github.com/pingcap/dm/pull/746)
+- Remove the redundant fields in the error message returned by `query-status` [#771](https://github.com/pingcap/dm/pull/771)
+- Improve the binlog position information of the upstream database returned by `query-status` [#830](https://github.com/pingcap/dm/pull/830)
+- Improve the processing of `auto resume` when an error is encountered during the full export [#872](https://github.com/pingcap/dm/pull/872)
+- Fix the issue of goroutine leak after executing `stop-task` [#731](https://github.com/pingcap/dm/pull/731)
+- Fix the issue that the task might not be paused after executing `pause-task` [#644](https://github.com/pingcap/dm/pull/644)
+- Fix the issue that the checkpoint might not be saved correctly in the initial stage of incremental replication [#758](https://github.com/pingcap/dm/pull/758)
+- Fix the issue that the `BIT` data type is incorrectly handled during incremental replication [#876](https://github.com/pingcap/dm/pull/876)
+
 ## [1.0.6] 2020-06-17
 
 ### Improvements