docs: add diagnostic tool docs

docs/en/maintain/diagnose.md

@@ -0,0 +1,82 @@
+# Diagnostic Tool
+
+## Overview
+
+OpenMLDB provides a diagnostic tool to diagnose problems conveniently for users. It can check items as below:
+
+- Version
+- Configuration
+- Log
+- Run test SQL
+
+## Usage
+
+1. Download diagnostic tool
+```bash
+pip install openmldb-tool
+```
+
+2. Config cluster distribution
+
+standalone yaml conf
+```yaml
+mode: standalone
+nameserver:
+  -
+    endpoint: 127.0.0.1:6527
+    path: /work/openmldb
+tablet:
+  -
+    endpoint: 127.0.0.1:9527
+    path: /work/openmldb
+```
+
+cluster yaml conf
+```yaml
+mode: cluster
+zookeeper:
+  zk_cluster: 127.0.0.1:2181
+  zk_root_path: /openmldb
+nameserver:
+  -
+    endpoint: 127.0.0.1:6527
+    path: /work/ns1
+tablet:
+  -
+    endpoint: 127.0.0.1:9527
+    path: /work/tablet1
+  -
+    endpoint: 127.0.0.1:9528
+    path: /work/tablet2
+taskmanager:
+  -
+    endpoint: 127.0.0.1:9902
+    path: /work/taskmanager1
+```
+
+3. Setup SSH Passwordless Login
+
+As diagnostic tool will pull conf and log files from remote nodes when checking cluster, SSH passwordless shoud be setup. If you do not konw how to set, you can refer [here]((https://www.itzgeek.com/how-tos/linux/centos-how-tos/ssh-passwordless-login-centos-7-rhel-7.html))
+
+4. Run diagnostic tool
+
+```bash
+openmldb_tool --dist_conf=/tmp/standalone_dist.yml
+```
+
+There are some advanced options can be specified as below:
+
+- --dist_conf: To config the distribution of cluster
+- --data_dir: The data dir to store the conf and log files pulled from remote. The default value is `/tmp/diagnose_tool_data`
+- --check: The item to check. The default value is `ALL`. It can be specified as `CONF/LOG/SQL/VERSION`
+- --exclude: The item do not check. Only work if `check` option is `ALL`. It can be specified as `CONF/LOG/SQL/VERSION`
+- --log_level: The default value is `info`. It can be specified as `debug/warn/info`
+- --log_dir: Specific the output dir. It will print to stdout if not set
+- --env: If the cluster is started with `start-all.sh` script, `onbox` should be setted.
+
+For instance, we can check `conf` only and print the ouput to local dir as below:
+```
+openmldb_tool --dist_conf=/tmp/cluster_dist.yml --check=conf --log_dir=./
+```
+
+**Note**: If you want to diagnostie standalone mode OpenMLDB, you need to run diagnostic tool on the OpenMLDB node.

docs/en/maintain/index.rst

@@ -10,4 +10,5 @@ Maintenance
     monitoring
     cli
     faq
-    scale
+    scale
+    diagnose

docs/zh/maintain/diagnose.md

@@ -0,0 +1,79 @@
+# 诊断工具
+
+## 概述
+
+为了方便排查用户环境中的常见问题，OpenMLDB提供了诊断工具。主要有以下功能:
+- 版本校验
+- 配置文件检查
+- 日志提取
+- 执行测试SQL
+
+## 使用
+
+1. 下载诊断工具包
+```bash
+    pip install openmldb-tool
+```
+
+2. 准备环境yaml配置文件
+
+单机版yaml
+```yaml
+mode: standalone
+nameserver:
+  -
+    endpoint: 127.0.0.1:6527
+    path: /work/openmldb
+tablet:
+  -
+    endpoint: 127.0.0.1:9527
+    path: /work/openmldb
+```
+
+集群版yaml
+```yaml
+mode: cluster
+zookeeper:
+  zk_cluster: 127.0.0.1:2181
+  zk_root_path: /openmldb
+nameserver:
+  -
+    endpoint: 127.0.0.1:6527
+    path: /work/ns1
+tablet:
+  -
+    endpoint: 127.0.0.1:9527
+    path: /work/tablet1
+  -
+    endpoint: 127.0.0.1:9528
+    path: /work/tablet2
+taskmanager:
+  -
+    endpoint: 127.0.0.1:9902
+    path: /work/taskmanager1
+```
+
+3. 添加机器互信
+
+    由于诊断工具需要到部署节点上拉取文件，所以需要添加机器互信免密。设置方法参考[这里](https://www.itzgeek.com/how-tos/linux/centos-how-tos/ssh-passwordless-login-centos-7-rhel-7.html)
+
+4. 执行诊断工具命令
+```bash
+openmldb_tool --dist_conf=/tmp/standalone_dist.yml
+```
+诊断工具所有参数如下:
+
+- --dist_conf OpenMLDB节点分布的配置文件
+- --data_dir 数据存放路径。会把远端的配置文件和日志等放在这个目录里，默认为/tmp/diagnose_tool_data
+- --check 检查项，默认为ALL即检查所有。还可以单独配置为CONF/LOG/SQL/VERSION，分别检查配置文件、日志、执行SQL、版本
+- --exclude 不检查其中某一项。只有check设置为ALL才会生效。可以配置为CONF/LOG/SQL/VERSION
+- --log_level 设置日志级别，默认为info。可以设置为debug/warn/info
+- --log_dir 设置结果输出路径，默认为标准输出
+- --env 如果用start-all.sh启动的集群，需要指定为onbox, 其他情况不需要指定
+
+例如指定只检查配置文件，并且结果输出到当前目录下
+```
+openmldb_tool --dist_conf=/tmp/cluster_dist.yml --check=conf --log_dir=./
+```
+
+**注**: 如果是单机版，诊断工具必须在单机版部署节点上执行  

docs/zh/maintain/index.rst

@@ -11,3 +11,4 @@
     monitoring
     cli
     faq
+    diagnose

docs/zh/reference/sql/dml/DELETE_STATEMENT.md

@@ -1,7 +1,5 @@
 # DELETE
 
-OpenMLDB supports single-row and multi-row insert statements
-
 ## 语法
 
 ```sql