Update upgrade-tidb-using-tiup.md

upgrade-tidb-using-tiup.md

@@ -13,7 +13,7 @@ If you have deployed the TiDB cluster using TiDB Ansible, you can use TiUP to im
 
 ## Upgrade caveat
 
-- Rolling back to 3.0 versions after the update is not supported.
+- After the upgrade, rolling back to 3.0 or earlier versions is not supported.
 - To update versions earlier than 3.0 to 4.0, first update this version to 3.0 using TiDB Ansible, and use TiUP to import the TiDB Ansible configuration and update the 3.0 version to 4.0.
 - After the TiDB Ansible configuration is imported into and managed by TiUP, you can no longer operate on the cluster using TiDB Ansible. Otherwise, conflicts might occur because of the inconsistent metadata.
 - Currently, you cannot import the TiDB Ansible configuration if the cluster deployed using TiDB Ansible meets one of the following situations:
@@ -24,6 +24,15 @@ If you have deployed the TiDB cluster using TiDB Ansible, you can use TiUP to im
     - `Lightning` / `Importer` is enabled for the cluster.
     - You still use the `'push'` method to collect monitoring metrics (since v3.0, `pull` is the default mode, which is supported if you have not modified this mode).
     - In the `inventory.ini` configuration file, the `node_exporter` or `blackbox_exporter` item of the machine is set to non-default ports through `node_exporter_port` or `blackbox_exporter_port`, which is compatible if you have unified the configuration in the `group_vars` directory.
+- Support upgrading the versions of TiDB Binlog, TiCDC, TiFlash, and other components.
+- Before you upgrade from v2.0.6 or earlier to v4.0.0 or later, you must make sure that no DDL operations are running in the cluster, especially the `Add Index` operation that is time-consuming. Perform the upgrade after all DDL operations are completed.
+- Starting from v2.1, TiDB enables parallel DDL. Therefore, clusters **older than v2.0.1** cannot be upgraded to v4.0.0 or later via a direct rolling upgrade. Instead, you can choose one of the following solutions:
+    - Upgrade directly from TiDB v2.0.1 or earlier to v4.0.0 or later in planned downtime
+    - Perform a rolling upgrade from the current version to v2.0.1 or a later 2.0 version, then perform another rolling upgrade to v4.0.0 or later
+
+> **Note:**
+>
+> Do not execute any DDL request during the upgrade, otherwise an undefined behavior issue might occur.
 
 ## Install TiUP on the control machine
 
@@ -61,6 +70,10 @@ If you have deployed the TiDB cluster using TiDB Ansible, you can use TiUP to im
 
 If you have installed TiUP before, execute the following command to update TiUP to the latest version:
 
+> **Note:**
+>
+> If the result of `tiup --version` shows that your TiUP version is earlier than v1.0.0, run `tiup update --self` first to update the TiUP version before running the following command.
+
 {{< copyable "shell-regular" >}}
 
 ```shell
@@ -74,10 +87,11 @@ tiup update cluster
 > + If the original cluster is deployed using TiUP, you can skip this step.
 > + Currently, the `inventory.ini` configuration file is identified by default. If your configuration file uses another name, specify this name.
 > + Ensure that the state of the current cluster is consistent with the topology in `inventory.ini`; that components of the cluster are operating normally. Otherwise, the cluster metadata becomes abnormal after the import.
+> + If multiple different `inventory.ini` files and TiDB clusters are managed in one TiDB Ansible directory, when importing one of the clusters into TiUP, you need to specify `--no-backup` to avoid moving the Ansible directory to the TiUP management directory.
 
 ### Import the TiDB Ansible cluster to TiUP
 
-1. Execute the following command to import the TiDB Ansible cluster into TiUP (for example, in the `/home/tidb/tidb-ansible` path). Do not execute this command in the Ansible directory.
+1. Execute the following command to import the TiDB Ansible cluster into TiUP (for example, in the `/home/tidb/tidb-ansible` path).
 
     {{< copyable "shell-regular" >}}
 
@@ -127,7 +141,7 @@ After the import is complete, you can check the current cluster status by execut
     tiup cluster edit-config <cluster-name>
     ```
 
-3. See the configuration template format of [topology](https://github.com/pingcap-incubator/tiup-cluster/blob/master/examples/topology.example.yaml) and fill in the modified parameters of the original cluster in the `server_configs` section of the topology file.
+3. See the configuration template format of [topology](https://github.com/pingcap/tiup/blob/master/examples/topology.example.yaml) and fill in the modified parameters of the original cluster in the `server_configs` section of the topology file.
 
     Even if the label has been configured for the cluster, you also need to fill in the label in the configuration according to the format in the template. In later versions, the label will be automatically imported.
 
@@ -137,19 +151,27 @@ After the import is complete, you can check the current cluster status by execut
 >
 > Before upgrading to v4.0, confirm that the parameters modified in v3.0 are compatible in v4.0. See [configuration template](/tikv-configuration-file.md) for details.
 
-## Perform a rolling update to the TiDB cluster
+## Perform a rolling upgrade to the TiDB cluster
 
-This section describes how to perform a rolling update to the TiDB cluster and how to verify the version after the update.
+This section describes how to perform a rolling upgrade to the TiDB cluster and how to verify the version after the upgrade.
 
-### Perform a rolling update to the TiDB cluster (to v4.0.0-rc)
+### Upgrade the TiDB cluster to a specified version
 
 {{< copyable "shell-regular" >}}
 
 ```shell
-tiup cluster upgrade <cluster-name> v4.0.0-rc
+tiup cluster upgrade <cluster-name> <version>
 ```
 
-Performing the rolling update to the cluster will update all components one by one. During the upgrade of TiKV, all leaders in a TiKV instance are evicted before stopping the instance. The default timeout time is 5 minutes. The instance is directly stopped after this timeout time.
+For example, if you want to upgrade the cluster to v4.0.0:
+
+{{< copyable "shell-regular" >}}
+
+```shell
+tiup cluster upgrade <cluster-name> v4.0.0
+```
+
+Performing a rolling upgrade to the cluster will upgrade all components one by one. During the upgrade of TiKV, all leaders in a TiKV instance are evicted before stopping the instance. The default timeout time is 5 minutes. The instance is directly stopped after this timeout time.
 
 To perform the upgrade immediately without evicting the leader, specify `--force` in the command above. This method causes performance jitter but not data loss.
 
@@ -166,55 +188,49 @@ tiup cluster display <cluster-name>
 ```
 
 ```
-Starting /home/tidblk/.tiup/components/cluster/v0.4.3/cluster display <cluster-name>
+Starting /home/tidblk/.tiup/components/cluster/v1.0.0/cluster display <cluster-name>
 TiDB Cluster: <cluster-name>
-TiDB Version: v4.0.0-rc
+TiDB Version: v4.0.0
 ```
 
 ## FAQ
 
 This section describes common problems encountered when updating the TiDB cluster using TiUP.
 
-### If an error occurs and the updated is interrupted, how to resume the update from the point of the interruption after fixing this error?
+### If an error occurs and the upgrade is interrupted, how to resume the upgrade after fixing this error?
 
-You can specify `--role` or `--node` to update the specified component or node. Here is the command:
+Re-execute the `tiup cluster upgrade` command to resume the upgrade. The upgrade operation restarts the nodes that have been previously upgraded. In subsequent 4.0 versions, TiDB will support resuming the upgrade from the interrupted point.
 
-{{< copyable "shell-regular" >}}
+### The evict leader has waited too long during the upgrade. How to skip this step for a quick upgrade?
 
-```shell
-tiup cluster upgrade <cluster-name> v4.0.0-rc --role tidb
-```
-
-or
-
-{{< copyable "shell-regular" >}}
-
-```shell
-tiup cluster upgrade <cluster-name> v4.0.0-rc --node <ID>
-```
-
-### The evict leader has waited too long during the update. How to skip this step for a quick update?
-
-You can specify `--force`. Then the processes of transferring PD leader and evicting TiKV leader are skipped during the update. The cluster is directly restarted to update the version, which has a great impact on the cluster that runs online. Here is the command:
+You can specify `--force`. Then the processes of transferring PD leader and evicting TiKV leader are skipped during the upgrade. The cluster is directly restarted to update the version, which has a great impact on the cluster that runs online. Here is the command:
 
 {{< copyable "shell-regular" >}}
 
 ```shell
-tiup cluster upgrade <cluster-name> v4.0.0-rc --force
+tiup cluster upgrade <cluster-name> v4.0.0 --force
 ```
 
-### How to update the version of tools such as pd-ctl after updating the TiDB cluster?
+### How to update the version of tools such as pd-ctl after upgrading the TiDB cluster?
 
-Currently, TiUP does not update and manage the version of tools. If you need the tool package of the latest version, directly download the TiDB package and replace `{version}` with the corresponding version such as `v4.0.0-rc`. Here is the download address:
+Currently, TiUP does not update and manage the version of tools. If you need the tool package of the latest version, directly download the TiDB package and replace `{version}` with the corresponding version such as `v4.0.0`. Here is the download address:
 
 {{< copyable "" >}}
 
 ```
 https://download.pingcap.org/tidb-{version}-linux-amd64.tar.gz
 ```
 
+### Failure to upgrade the TiFlash component during the cluster upgrade
+
+Before v4.0.0-rc.2, TiFlash might have some incompatibility issues. This might cause problems when you upgrade a cluster that includes the TiFlash component to v4.0.0-rc.2 or a later version. If so, [contact the R&D support](mailto:[email protected]).
+
 ## TiDB 4.0 compatibility changes
 
 - If you set the value of the `oom-action` parameter to `cancel`, when the query statement triggers the OOM threshold, the statement is killed. In v4.0, in addition to `select`, DML statements such as `insert`/`update`/`delete` might also be killed.
 - TiDB v4.0 supports the length check for table names. The length limit is 64 characters. If you rename a table after the upgrade and the new name exceeds this length limit, an error is reported. v3.0 and earlier versions do not have this error reporting.
+- TiDB v4.0 supports the length check for partition names of the partitioned tables. The length limit is 64 characters. After the upgrade, if you create or alter a partitioned table with a partition name that exceeds the length limit, an error is expected to occur in 4.0 versions, but not in 3.0 and earlier versions.
 - In v4.0, the format of the `explain` execution plan is improved. Pay attention to any automatic analysis program that is customized for `explain`.
+- TiDB v4.0 supports [Read Committed isolation level](/transaction-isolation-levels.md#read-committed-isolation-level). After upgrading to v4.0, setting the isolation level to `READ-COMMITTED` in a pessimistic transaction takes effect. In 3.0 and earlier versions, the setting does not take effect.
+- In v4.0, executing `alter reorganize partition` returns an error. In earlier versions, no error is reported because only the syntax is supported and the statement is not taking any effect.
+- In v4.0, creating `linear hash partition` or `subpartition` tables does not take effect and they are converted to regular tables. In earlier versions, they are converted to regular partitioned tables.