add cn doc

docs-2.0/3.ngql-guide/6.functions-and-expressions/13.concat.md

@@ -0,0 +1,109 @@
+# concat function
+
+The `concat()` and `concat_ws()` functions return strings concatenated by one or more strings.
+
+## concat() function
+
+The `concat()` function requires at least two or more strings. All the parameters are concatenated into one string.
+
+- If there is only one string, the string itself is returned.
+
+- If any one of the string is `NULL`, `NULL` is returned.
+
+### Syntax
+
+```bash
+concat(string1,string2,...)
+```
+
+### Examples
+
+```bash
+//This example concatenates 1, 2, and 3.
+nebula> RETURN concat("1","2","3") AS r;
++-------+
+| r     |
++-------+
+| "123" |
++-------+
+
+//In this example, one of the string is NULL.
+nebula> RETURN concat("1","2",NULL) AS r;
++----------+
+| r        |
++----------+
+| __NULL__ |
++----------+
+
+nebula> GO FROM "player100" over follow \
+        YIELD concat(follow._src, $^.player.age, $$.player.name, follow.degree) AS A;
++------------------------------+
+| A                            |
++------------------------------+
+| "player10042Tony Parker95"   |
++------------------------------+
+| "player10042Manu Ginobili95" |
++------------------------------+
+```
+
+## concat_ws() function
+
+The `concat_ws()` function connects two or more strings with a predefined separator.
+
+- If the separator is `NULL`, the `concat_ws()` function returns `NULL`.
+
+- If the separator is not `NULL` and there is only one string, the string itself is returned.
+
+- If the separator is not `NULL` and there is a `NULL` in the strings, `NULL` is ignored during the concatenation.
+
+### Syntax
+
+```bash
+concat_ws(separator,string1,string2,... )
+```
+
+### Examples
+
+```bash
+//This example concatenates a, b, and c with the separator +.
+nebula> RETURN concat_ws("+","a","b","c") AS r;
++---------+
+| r       |
++---------+
+| "a+b+c" |
++---------+
+
+//In this example, the separator is NULL.
+neubla> RETURN concat_ws(NULL,"a","b","c") AS r;
++----------+
+| r        |
++----------+
+| __NULL__ |
++----------+
+
+//In this example, the separator is + and there is a NULL in the strings.
+nebula> RETURN concat_ws("+","a",NULL,"b","c") AS r;
++---------+
+| r       |
++---------+
+| "a+b+c" |
++---------+
+
+//In this example, the separator is + and there is only one string.
+nebula> RETURN concat_ws("+","a") AS r;
++-----+
+| r   |
++-----+
+| "a" |
++-----+
+
+nebula> GO FROM "player100" over follow \
+        YIELD concat_ws(" ",follow._src, $^.player.age, $$.player.name, follow.degree) AS A;
++---------------------------------+
+| A                               |
++---------------------------------+
+| "player100 42 Tony Parker 95"   |
++---------------------------------+
+| "player100 42 Manu Ginobili 95" |
++---------------------------------+
+```

docs-2.0/3.ngql-guide/7.general-query-statements/6.show/19.show-meta-leader.md

@@ -0,0 +1,27 @@
+# SHOW META LEADER
+
+The `SHOW META LEADER` statement shows the information of the leader in the current Meta cluster.
+
+For more information about the Meta service, see [Meta service](../../../1.introduction/3.nebula-graph-architecture/2.meta-service.md).
+
+## Syntax
+
+```ngql
+SHOW META LEADER;
+```
+
+## Example
+
+```ngql
+nebula> SHOW META LEADER;
++------------------+---------------------------+
+| Meta Leader      | secs from last heart beat |
++------------------+---------------------------+
+| "127.0.0.1:9559" | 3                         |
++------------------+---------------------------+
+```
+
+|Parameter|Description|
+|:---|:---|
+|`Meta Leader`|Shows the information of the leader in the Meta cluster, including the IP address and port of the server where the leader is located.|
+|`secs from last heart beat`|Indicates the time interval since the last heartbeat. This parameter is measured in seconds.|

docs-2.0/7.data-security/1.authentication/4.ldap.md

@@ -0,0 +1,103 @@
+<!--
+# 使用OpenLDAP进行身份验证
+
+本文介绍如何将Nebula Graph连接到OpenLDAP服务器，使用OpenLDAP中定义的DN（Distinguished Name）和密码进行身份验证。
+
+!!! enterpriseonly
+
+    仅企业版支持本功能。
+
+## 认证方式
+
+启用OpenLDAP身份验证后，输入用户的账号和密码登录Nebula Graph时，Nebula Graph会在Meta服务中查找登录账号是否存在，如果账号存在，再根据认证方式去OpenLDAP中找到对应的DN，验证密码。
+
+OpenLDAP支持的认证方式有两种：简单绑定认证和搜索绑定认证。
+
+### 简单绑定认证（SimpleBindAuth）
+
+简单绑定认证会根据登录账号和Graph服务配置信息，拼接成OpenLDAP可以识别的DN，然后根据DN和密码，在OpenLDAP上进行验证。
+
+### 搜索绑定认证（SearchBindAuth）
+
+搜索绑定认证会读取Graph服务配置信息，查询配置信息中的`uid`和登录账号是否匹配，如果匹配，就读取这个DN，然后用DN和密码，在OpenLDAP上进行验证。
+
+## 前提条件
+
+- 已安装[OpenLDAP](https://www.openldap.org/)。
+
+- 已在OpenLDAP上导入用户的账号和密码信息。
+
+- OpenLDAP所在服务器已开放相应认证端口。
+
+## 操作步骤
+
+以OpenLDAP上已存在的账号`test2`、密码`passwdtest2`为例进行演示。
+
+1. [连接Nebula Graph](../../4.deployment-and-installation/connect-to-nebula-graph.md)，创建与OpenLDAP中对应的影子账号`test2`并授权。
+
+  ```ngql
+  nebula> CREATE USER test2 WITH PASSWORD '';
+  nebula> GRANT ROLE ADMIN ON basketballplayer TO test2;
+  ```
+
+    !!! note
+
+        Nebula Graph内创建用户时，密码可以任意设置。
+
+2. 编辑配置文件`nebula-graphd.conf`（默认目录为`/usr/local/nebula/etc/`）：
+
+  - 简单绑定认证（推荐）
+
+    ```bash
+    # 是否从配置文件获取配置信息。
+    --local_config=true
+    # 是否开启身份验证
+    --enable_authorize=true
+    # 身份验证方式：password、ldap、cloud
+    --auth_type=ldap
+    # OpenLDAP服务器地址
+    --ldap_server=192.168.8.211
+    # OpenLDAP服务器端口
+    --ldap_port=389
+    # OpenLDAP中的Schema名称
+    --ldap_scheme=ldap
+    # DN前缀
+    --ldap_prefix=uid=
+    # DN后缀
+    --ldap_suffix=,ou=it,dc=sys,dc=com
+    ```
+
+  - 搜索绑定认证
+
+    ```bash
+    # 是否从配置文件获取配置信息。
+    --local_config=true
+    # 是否开启身份验证
+    --enable_authorize=true
+    # 身份验证方式：password、ldap、cloud
+    --auth_type=ldap
+    # OpenLDAP服务器地址
+    --ldap_server=192.168.8.211
+    # OpenLDAP服务器端口
+    --ldap_port=389
+    # OpenLDAP中的Schema名称
+    --ldap_scheme=ldap
+    # 绑定目标对象的DN
+    --ldap_basedn=uid=test2,ou=it,dc=sys,dc=com
+    ```
+
+3. [重启Nebula Graph服务](../../4.deployment-and-installation/manage-service.md)，让新配置生效。
+
+4. 进行登录测试。
+
+  ```bash
+  $ ./nebula-console --addr 127.0.0.1 --port 9669 -u test2 -p passwdtest2
+  2021/09/08 03:49:39 [INFO] connection pool is initialized successfully
+
+  Welcome to Nebula Graph!
+  ```
+
+    !!! note
+
+        使用OpenLDAP进行身份验证后，本地用户（包括`root`）无法正常登录。
+-->

docs-2.0/8.service-tuning/improve-query-by-tag-index.md

@@ -0,0 +1,53 @@
+<!-->
+# 增加和删除标签
+
+在openCypher中，有增加标签（`SET label`）和移除标签（`REMOVE label`）的功能，可以用于加速查询或者标记过程。
+
+在Nebula Graph中，可以通过Tag变相实现相同操作，创建Tag并将Tag插入到已有的点上，就可以根据Tag名称快速查找点，也可以通过`DELETE TAG`删除某些点上不再需要的Tag。
+
+!!! caution
+
+    请确保点上已经有另一个Tag，否则删除点上最后一个Tag时，会导致点也被删除。
+
+## 示例
+
+例如在basketballplayer数据集中，部分篮球运动员同时也是球队股东，可以为股东Tag`shareholder`创建索引，方便快速查找。如果不再是股东，可以通过`DELETE TAG`语句删除相应运动员的股东Tag。
+
+```ngql
+//创建股东Tag和索引
+nebula> CREATE TAG shareholder();
+nebula> CREATE TAG INDEX shareholder_tag on shareholder();
+//为点添加Tag
+nebula> INSERT VERTEX shareholder() VALUES "player100":();
+nebula> INSERT VERTEX shareholder() VALUES "player101":();
+//快速查询所有股东
+nebula> MATCH (v:shareholder) RETURN v;
++---------------------------------------------------------------------+
+| v                                                                   |
++---------------------------------------------------------------------+
+| ("player100" :player{age: 42, name: "Tim Duncan"} :shareholder{})  |
++---------------------------------------------------------------------+
+| ("player101" :player{age: 36, name: "Tony Parker"} :shareholder{}) |
++---------------------------------------------------------------------+
+nebula> LOOKUP ON shareholder;
++-------------+
+| VertexID    |
++-------------+
+| "player100" |
++-------------+
+| "player101" |
++-------------+
+//如果player100不再是股东
+nebula> DELETE TAG shareholder FROM "player100";
+nebula> LOOKUP ON shareholder;
++-------------+
+| VertexID    |
++-------------+
+| "player101" |
++-------------+
+```
+
+!!! note
+
+    如果插入测试数据后才创建索引，请用`REBUILD TAG INDEX <index_name_list>;`语句重建索引。
+-->

mkdocs.yml

@@ -162,6 +162,7 @@ nav:
           - collect(): 3.ngql-guide/6.functions-and-expressions/10.collect.md
           - reduce(): 3.ngql-guide/6.functions-and-expressions/11.reduce.md
           - hash(): 3.ngql-guide/6.functions-and-expressions/12.hash.md
+          - concat(): 3.ngql-guide/6.functions-and-expressions/13.concat.md
           - Predicate functions: 3.ngql-guide/6.functions-and-expressions/8.predicate.md
           - User-defined functions: 3.ngql-guide/6.functions-and-expressions/9.user-defined-functions.md
 
@@ -189,6 +190,7 @@ nav:
             - SHOW USERS: 3.ngql-guide/7.general-query-statements/6.show/16.show-users.md
             - SHOW SESSIONS: 3.ngql-guide/7.general-query-statements/6.show/17.show-sessions.md
             - SHOW QUERIES: 3.ngql-guide/7.general-query-statements/6.show/18.show-queries.md
+            - SHOW META LEADER: 3.ngql-guide/7.general-query-statements/6.show/19.show-meta-leader.md
 
       - Clauses and options:
           - GROUP BY: 3.ngql-guide/8.clauses-and-options/group-by.md
@@ -213,6 +215,8 @@ nav:
           - ALTER TAG: 3.ngql-guide/10.tag-statements/3.alter-tag.md
           - SHOW TAGS: 3.ngql-guide/10.tag-statements/4.show-tags.md
           - DESCRIBE TAG: 3.ngql-guide/10.tag-statements/5.describe-tag.md
+          - DELETE TAG: 3.ngql-guide/10.tag-statements/6.delete-tag.md
+
       - Edge type statements:
           - CREATE EDGE: 3.ngql-guide/11.edge-type-statements/1.create-edge.md
           - DROP EDGE: 3.ngql-guide/11.edge-type-statements/2.drop-edge.md
@@ -295,6 +299,7 @@ nav:
           - Authentication: 7.data-security/1.authentication/1.authentication.md
           - User management: 7.data-security/1.authentication/2.management-user.md
           - Roles and privileges: 7.data-security/1.authentication/3.role-list.md
+          - OpenLDAP authentication: 7.data-security/1.authentication/4.ldap.md
 #      - Backup & Restore:
 #          - What is Backup & Restore: 7.data-security/2.backup-restore/1.what-is-br.md
 #          - Compile BR: 7.data-security/2.backup-restore/2.compile-br.md
@@ -309,6 +314,7 @@ nav:
     - System design suggestions: 8.service-tuning/3.system-design.md
     - Execution plan: 8.service-tuning/4.plan.md
     - Processing super vertices: 8.service-tuning/super-node.md
+    - Add or delete tag: 8.service-tuning/improve-query-by-tag-index.md
 
   - Client:
     - Clients overview: 14.client/1.nebula-client.md