releases: add v4.0.9 release notes

TOC.md

@@ -529,6 +529,7 @@
   + [All Releases](/releases/release-notes.md)
   + [TiDB Roadmap](/roadmap.md)
   + v4.0
+    + [4.0.9](/releases/release-4.0.9.md)
     + [4.0.8](/releases/release-4.0.8.md)
     + [4.0.7](/releases/release-4.0.7.md)
     + [4.0.6](/releases/release-4.0.6.md)

releases/release-4.0.9.md

@@ -0,0 +1,168 @@
+---
+title: TiDB 4.0.9 Release Notes
+---
+
+# TiDB 4.0.9 Release Notes
+
+Release date: December 3, 2020
+
+TiDB version: 4.0.9
+
+## Compatibility changes
+
++ TiDB
+
+    - Deprecate `enable-streaming` [#21055](https://github.com/pingcap/tidb/pull/21055)
+
+## New Features
+
++ TiFlash
+
+    - Support storing the latest data of the storage engine on multiple disks
+
+## Improvements
+
++ TiDB
+
+    - Ban (index) merge join heuristically when converting equal conditions to other conditions. [#21146](https://github.com/pingcap/tidb/pull/21146)
+    - Differentiate types for user variables [#21107](https://github.com/pingcap/tidb/pull/21107)
+    - Allow set GOGC in the config file. [#20922](https://github.com/pingcap/tidb/pull/20922)
+    - Make dump binary time more compatible with MySQL [#21135](https://github.com/pingcap/tidb/pull/21135)
+    - TiDB now provides an error for statements that use the syntax `LOCK IN SHARE MODE`. This helps alert users that this feature is not implemented by TiDB, but a workaround to restore the previous behavior is available by setting `tidb_enable_noop_functions=1`. [#21005](https://github.com/pingcap/tidb/pull/21005)
+    - Avoid unnecessary warnings/errors when folding constants in shortcut-able expressions [#21040](https://github.com/pingcap/tidb/pull/21040)
+    - Raise an error when preparing the `load data` statement. [#21199](https://github.com/pingcap/tidb/pull/21199)
+    - Ignore integer zero-fill size attribute when changing the column types [#20986](https://github.com/pingcap/tidb/pull/20986)
+    - Add runtime information for DML in explain analyze [#21066](https://github.com/pingcap/tidb/pull/21066)
+    - Disallow multi-updates on the primary key (i.e. updating primary key of the same table with different alias) [#21113](https://github.com/pingcap/tidb/pull/21113)
+    - Add metric for connection idle time [#21301](https://github.com/pingcap/tidb/pull/21301)
+
++ TiKV
+
+    - Add tag to split command to trace its source [#8936](https://github.com/tikv/tikv/pull/8936)
+    - Support changing config pessimistic-txn.pipelined dynamically [#9100](https://github.com/tikv/tikv/pull/9100)
+    - Running checksum in BR and Lightning should have less influence on the cluster performance. [#9098](https://github.com/tikv/tikv/pull/9098)
+    - Add a metrics for ingesting sst errors [#9096](https://github.com/tikv/tikv/pull/9096)
+    - Prevent hibernation when there are still peers catching up logs [#9093](https://github.com/tikv/tikv/pull/9093)
+    - Increase the success rate of pipelined pessimistic locking. [#9086](https://github.com/tikv/tikv/pull/9086)
+    - Change the default value of `apply-max-batch-size` and `store-max-batch-size` to 1024 [#9020](https://github.com/tikv/tikv/pull/9020)
+    - Add config for max-background-flushes [#8947](https://github.com/tikv/tikv/pull/8947)
+    - Enable the unified read pool for the storage module by default. [#8887](https://github.com/tikv/tikv/pull/8887)
+
++ PD
+
+    - Check cluster version on stores become tombstone [#3213](https://github.com/pingcap/pd/pull/3213)
+    - The store of lower version is no longer allowed to change from `Tombstone` back to `Up`.[#3206](https://github.com/pingcap/pd/pull/3206)
+    - Dashboard: update to v2020.11.26.1 [#3219](https://github.com/pingcap/pd/pull/3219)
+
++ TiFlash
+
+    - Reduce the latency of replica reads
+    - Refine TiFlash's error message
+    - Limit the memory usage of cache data under huge volume data
+    - Add a metric for the number of handling coprocessor tasks
+
++ Tools
+
+    + Backup & Restore (BR)
+
+        - BR no longer accepts --checksum false in command line, which did not disable checksum. The correct usage always include the = sign: --checksum=false [#588](https://github.com/pingcap/br/pull/588)
+        - Support change PD config temporary [#596](https://github.com/pingcap/br/pull/596)
+        - Support analyze table after restore [#622](https://github.com/pingcap/br/pull/622)
+        - Retry for read index not ready and proposal in merging mode [#626](https://github.com/pingcap/br/pull/626)
+
+    + TiCDC
+
+        - Metrics: add alert for tikv hibernate regions [#1120](https://github.com/pingcap/ticdc/pull/1120)
+        - Reduce memory usage in schema storage by avoiding table info replication [#1127](https://github.com/pingcap/ticdc/pull/1127)
+
+    + Dumpling
+
+        - Retry dumping on failed chunks [#182](https://github.com/pingcap/dumpling/pull/182)
+        - Support configuring both -F and -r arguments at the same time [#177](https://github.com/pingcap/dumpling/pull/177)
+        - Exclude system databases in --filter parameter by default [#194](https://github.com/pingcap/dumpling/pull/194)
+        - Support --transactional-consistency parameter and support rebuild mysql connections during retry [#199](https://github.com/pingcap/dumpling/pull/199)
+
+    + TiDB Lightning
+
+        - Filter out all system schemas by default [#459](https://github.com/pingcap/tidb-lightning/pull/459)
+        - Support set a default value for auto random primary key for local/importer backend [#457](https://github.com/pingcap/tidb-lightning/pull/457)
+        - Use range properties to make range split more precise with local backend [#422](https://github.com/pingcap/tidb-lightning/pull/422)
+        - `tikv-importer.region-split-size`, `mydumper.read-block-size`, `mydumper.batch-size` and `mydumper.max-region-size` can now accept human-readable format in the form "2.5 GiB" [#471](https://github.com/pingcap/tidb-lightning/pull/471)
+
+    + TiDB Binlog
+
+        - Exit Drainer process with non-zero code if upstream PD is down or apply DDL/DML to downstream failed [#1012](https://github.com/pingcap/tidb-binlog/pull/1012)
+
+## Bug Fixes
+
++ TiDB
+
+    - Fix incorrect results when using a prefix index with OR condition [#21287](https://github.com/pingcap/tidb/pull/21287)
+    - Fix a bug that causes panic when `retry` is enabled. [#21285](https://github.com/pingcap/tidb/pull/21285)
+    - Fix a bug of partition definition checking. The value comparison should be in accord with column type [#21273](https://github.com/pingcap/tidb/pull/21273)
+    - Fix a bug of partition table's partition column values type check [#21136](https://github.com/pingcap/tidb/pull/21136)
+    - Fix a bug that hash type partition does not check partition name is unique [#21257](https://github.com/pingcap/tidb/pull/21257)
+    - Fix insert value into hash partition table which not int [#21238](https://github.com/pingcap/tidb/pull/21238)
+    - Fix unexpected error when `INSERT` meets index join in some cases. [#21249](https://github.com/pingcap/tidb/pull/21249)
+    - Fix bigint unsigned column value in CASE WHEN operator is converted to bigint signed  [#21236](https://github.com/pingcap/tidb/pull/21236)
+    - Fix a bug that index-hash-join and index-merge-join doesn't consider collation [#21219](https://github.com/pingcap/tidb/pull/21219)
+    - Fix a bug that partition table does not consider collation in `create table` and `select` sentence. [#21181](https://github.com/pingcap/tidb/pull/21181)
+    - Fix issue of the query result of slow_query maybe miss some rows. [#21211](https://github.com/pingcap/tidb/pull/21211)
+    - `DELETE` may not delete data correctly when the database name is not in pure lower representation. [#21206](https://github.com/pingcap/tidb/pull/21206)
+    - Fix a bug causes schema change after DML [#21050](https://github.com/pingcap/tidb/pull/21050)
+    - Fix the bug that can not query the coalesced column when use using-join. [#21021](https://github.com/pingcap/tidb/pull/21021)
+    - Fix wrong results for some semi-join queries. [#21019](https://github.com/pingcap/tidb/pull/21019)
+    - Fix table lock for update statement. [#21002](https://github.com/pingcap/tidb/pull/21002)
+    - Fix stack overflow when building recursive view. [#21001](https://github.com/pingcap/tidb/pull/21001)
+    - Fix unexpected results when do merge join on outer join [#20954](https://github.com/pingcap/tidb/pull/20954)
+    - Fix the issue that sometimes a transaction that has an undetermined result may be treated as failed. [#20925](https://github.com/pingcap/tidb/pull/20925)
+    - Fix issue `explain for connection` can't show the last query plan/ [#21315](https://github.com/pingcap/tidb/pull/21315)
+    - Fix the issue that when Index Merge is used in a transaction with RC isolation level, the result may be incorrect. [#21253](https://github.com/pingcap/tidb/pull/21253)
+    - Fix auto-id allocation failed because of the transaction's write-conflict retry. [#21079](https://github.com/pingcap/tidb/pull/21079)
+    - Fix The JSON Data can not import to TiDB correctly by `load data` [#21074](https://github.com/pingcap/tidb/pull/21074)
+    - Set correct default value for new added enum column. [#20998](https://github.com/pingcap/tidb/pull/20998)
+    - Expression: keep the original data type when doing date arithmetic operations [#21176](https://github.com/pingcap/tidb/pull/21176)
+    - Fix the wrong point get plan generation in fast plan code path [#21244](https://github.com/pingcap/tidb/pull/21244)
+
++ TiKV
+
+    - Fix a bug that Coprocessor may return wrong result when there are > 255 columns. [#9131](https://github.com/tikv/tikv/pull/9131)
+    - Fix an issue that region merge may cause data loss during network partition. [#9108](https://github.com/tikv/tikv/pull/9108)
+    - Fix a bug may cause analyze statement panic when using the latin1 character set. [#9082](https://github.com/tikv/tikv/pull/9082)
+    - Fix cast decimal as time expr get wrong result when deal with numbers argument [#9031](https://github.com/tikv/tikv/pull/9031)
+    - Fix the bug that lightning fails to ingest sst files to tikv with importer/local backend when TDE is enabled [#8995](https://github.com/tikv/tikv/pull/8995)
+    - Config: fix invalid advertise-status-addr [#9036](https://github.com/tikv/tikv/pull/9036)
+    - Fix the issue that reports a key-exist error when a key is locked and deleted by a committed transaction. [#8930](https://github.com/tikv/tikv/pull/8930)
+    - Add check to avoid corruption due to RocksDB block cache error #8243. Also disable `force-consistency-checks` by default to improve performance. [#9029](https://github.com/tikv/tikv/pull/9029)
+
++ PD
+
+    - Fix the issue that the leader role does not take effect when using the replacement rule in some cases [#3208](https://github.com/pingcap/pd/pull/3208)
+    - Fix the bug that `trace-region-flow` will be accidentally changed to `false`. [#3120](https://github.com/pingcap/pd/pull/3120)
+    - Fix a bug that service safe points with infinite TTL may disappear. [#3143](https://github.com/pingcap/pd/pull/3143)
+
++ TiFlash
+
+    - Fix the problem that `INFORMATION_SCHEMA.CLUSTER_HARDWARE` may contain information about disks not in use
+    - Fix the issue that the memory consumption statistic of Delta Cache is smaller than actual the usage
+
++ Tools
+
+    + Backup & Restore (BR)
+
+        - Fix special characters in S3 secret access keys [#617](https://github.com/pingcap/br/pull/617)
+
+    + TiCDC
+
+        - Fix the bug that multiple owners could exist when owner campaign key is deleted [#1104](https://github.com/pingcap/ticdc/pull/1104)
+        - Kafka_consumer: fix wrong timezone when 'TZ' env is not set and downstream is mysql [#1095](https://github.com/pingcap/ticdc/pull/1095)
+
+    + Dumpling
+
+        - Fix the problem that dumpling may get blocked when its connection to database server is closed [#190](https://github.com/pingcap/dumpling/pull/190)
+
+    + TiDB Lightning
+
+        - Fix a bug about encoding data with wrong field info [#437](https://github.com/pingcap/tidb-lightning/pull/437)
+        - Fix a bug that gc life time ttl does not take effect [#448](https://github.com/pingcap/tidb-lightning/pull/448)
+        - Fix a bug that causes panic when manually stops Lightning import in Local-backend mode [#484](https://github.com/pingcap/tidb-lightning/pull/484)

releases/release-notes.md

@@ -7,6 +7,7 @@ aliases: ['/docs/dev/releases/release-notes/','/docs/dev/releases/rn/']
 
 ## 4.0
 
+- [4.0.9](/releases/release-4.0.9.md)
 - [4.0.8](/releases/release-4.0.8.md)
 - [4.0.7](/releases/release-4.0.7.md)
 - [4.0.6](/releases/release-4.0.6.md)