change create sentence in nGQL (#1198)

vesoft-inc · Nov 10, 2021 · 917d8e7 · 917d8e7
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diff --git a/docs-2.0/20.appendix/0.FAQ.md b/docs-2.0/20.appendix/0.FAQ.md
@@ -145,7 +145,7 @@ Storage 服务使用 Raft 协议（多数表决），为保证可用性，要求
 1. 建立并重建索引。
 
    ```ngql
-   > CREATE TAG INDEX i_player ON player();
+   > CREATE TAG INDEX IF NOT EXISTS i_player ON player();
    > REBUILD TAG INDEX i_player;
    ```
 
@@ -183,7 +183,7 @@ nGQL 没有该功能。
 或者通过一个属性索引来得到，例如：
 
 ```ngql
-# CREATE TAG INDEX i_player ON player(name(20));
+# CREATE TAG INDEX IF NOT EXISTS i_player ON player(name(20));
 # REBUILD TAG INDEX i_player;
 
 > LOOKUP ON player WHERE player.name == "abc" | ... YIELD ...

diff --git a/docs-2.0/3.ngql-guide/1.nGQL-overview/1.overview.md b/docs-2.0/3.ngql-guide/1.nGQL-overview/1.overview.md
@@ -59,7 +59,7 @@ CREATE {TAG | EDGE} {<tag_name> | <edge_type>}(<property_name> <data_type>
 示例语句：
 
 ```ngql
-nebula> CREATE TAG player(name string, age int);
+nebula> CREATE TAG IF NOT EXISTS player(name string, age int);
 ```
 
 ## 关于openCypher兼容性

diff --git a/docs-2.0/3.ngql-guide/1.nGQL-overview/identifier-case-sensitivity.md b/docs-2.0/3.ngql-guide/1.nGQL-overview/identifier-case-sensitivity.md
@@ -5,7 +5,7 @@
 以下语句会出现错误，因为`my_space`和`MY_SPACE`是两个不同的图空间。
 
 ```ngql
-nebula> CREATE SPACE my_space (vid_type=FIXED_STRING(30));
+nebula> CREATE SPACE IF NOT EXISTS my_space (vid_type=FIXED_STRING(30));
 nebula> use MY_SPACE;
 [ERROR (-8)]: SpaceNotFound:
 ```

diff --git a/docs-2.0/3.ngql-guide/10.tag-statements/1.create-tag.md b/docs-2.0/3.ngql-guide/10.tag-statements/1.create-tag.md
@@ -43,16 +43,16 @@ CREATE TAG [IF NOT EXISTS] <tag_name>
 ## 示例
 
 ```ngql
-nebula> CREATE TAG player(name string, age int);
+nebula> CREATE TAG IF NOT EXISTS player(name string, age int);
 
 # 创建没有属性的Tag。
-nebula> CREATE TAG no_property(); 
+nebula> CREATE TAG IF NOT EXISTS no_property(); 
 
 # 创建包含默认值的Tag。
-nebula> CREATE TAG player_with_default(name string, age int DEFAULT 20);
+nebula> CREATE TAG IF NOT EXISTS player_with_default(name string, age int DEFAULT 20);
 
 # 对字段create_time设置TTL为100秒。
-nebula> CREATE TAG woman(name string, age int, \
+nebula> CREATE TAG IF NOT EXISTS woman(name string, age int, \
         married bool, salary double, create_time timestamp) \
         TTL_DURATION = 100, TTL_COL = "create_time";
 ```

diff --git a/docs-2.0/3.ngql-guide/10.tag-statements/2.drop-tag.md b/docs-2.0/3.ngql-guide/10.tag-statements/2.drop-tag.md
@@ -29,6 +29,6 @@ DROP TAG [IF EXISTS] <tag_name>;
 ## 示例
 
 ```ngql
-nebula> CREATE TAG test(p1 string, p2 int);
+nebula> CREATE TAG IF NOT EXISTS test(p1 string, p2 int);
 nebula> DROP TAG test;
 ```
diff --git a/docs-2.0/3.ngql-guide/10.tag-statements/3.alter-tag.md b/docs-2.0/3.ngql-guide/10.tag-statements/3.alter-tag.md
@@ -32,7 +32,7 @@ ttl_definition:
 ## 示例
 
 ```ngql
-nebula> CREATE TAG t1 (p1 string, p2 int);
+nebula> CREATE TAG IF NOT EXISTS t1 (p1 string, p2 int);
 nebula> ALTER TAG t1 ADD (p3 int, p4 string);
 nebula> ALTER TAG t1 TTL_DURATION = 2, TTL_COL = "p2";
 nebula> ALTER TAG t1 COMMENT = 'test1';

diff --git a/docs-2.0/3.ngql-guide/10.tag-statements/6.delete-tag.md b/docs-2.0/3.ngql-guide/10.tag-statements/6.delete-tag.md
@@ -25,8 +25,8 @@ DELETE TAG <tag_name_list> FROM <VID>;
 ## 示例
 
 ```ngql
-nebula> CREATE TAG test1(p1 string, p2 int);
-nebula> CREATE TAG test2(p3 string, p4 int);
+nebula> CREATE TAG IF NOT EXISTS test1(p1 string, p2 int);
+nebula> CREATE TAG IF NOT EXISTS test2(p3 string, p4 int);
 nebula> INSERT VERTEX test1(p1, p2),test2(p3, p4) VALUES "test":("123", 1, "456", 2);
 nebula> FETCH PROP ON * "test";
 +------------------------------------------------------------+

diff --git a/docs-2.0/3.ngql-guide/10.tag-statements/improve-query-by-tag-index.md b/docs-2.0/3.ngql-guide/10.tag-statements/improve-query-by-tag-index.md
@@ -14,8 +14,8 @@
 
 ```ngql
 //创建股东Tag和索引
-nebula> CREATE TAG shareholder();
-nebula> CREATE TAG INDEX shareholder_tag on shareholder();
+nebula> CREATE TAG IF NOT EXISTS shareholder();
+nebula> CREATE TAG INDEX IF NOT EXISTS shareholder_tag on shareholder();
 
 //为点添加Tag
 nebula> INSERT VERTEX shareholder() VALUES "player100":();

diff --git a/docs-2.0/3.ngql-guide/11.edge-type-statements/1.create-edge.md b/docs-2.0/3.ngql-guide/11.edge-type-statements/1.create-edge.md
@@ -43,15 +43,15 @@ CREATE EDGE [IF NOT EXISTS] <edge_type_name>
 ### 示例
 
 ```ngql
-nebula> CREATE EDGE follow(degree int);
+nebula> CREATE EDGE IF NOT EXISTS follow(degree int);
 
 # 创建没有属性的Edge type。
-nebula> CREATE EDGE no_property();
+nebula> CREATE EDGE IF NOT EXISTS no_property();
 
 # 创建包含默认值的Edge type。
-nebula> CREATE EDGE follow_with_default(degree int DEFAULT 20);
+nebula> CREATE EDGE IF NOT EXISTS follow_with_default(degree int DEFAULT 20);
 
 # 对字段p2设置TTL为100秒。
-nebula> CREATE EDGE e1(p1 string, p2 int, p3 timestamp) \
+nebula> CREATE EDGE IF NOT EXISTS e1(p1 string, p2 int, p3 timestamp) \
         TTL_DURATION = 100, TTL_COL = "p2";
 ```
diff --git a/docs-2.0/3.ngql-guide/11.edge-type-statements/2.drop-edge.md b/docs-2.0/3.ngql-guide/11.edge-type-statements/2.drop-edge.md
@@ -25,6 +25,6 @@ DROP EDGE [IF EXISTS] <edge_type_name>
 ## 示例
 
 ```ngql
-nebula> CREATE EDGE e1(p1 string, p2 int);
+nebula> CREATE EDGE IF NOT EXISTS e1(p1 string, p2 int);
 nebula> DROP EDGE e1;
 ```
diff --git a/docs-2.0/3.ngql-guide/11.edge-type-statements/3.alter-edge.md b/docs-2.0/3.ngql-guide/11.edge-type-statements/3.alter-edge.md
@@ -32,7 +32,7 @@ ttl_definition:
 ## 示例
 
 ```ngql
-nebula> CREATE EDGE e1(p1 string, p2 int);
+nebula> CREATE EDGE IF NOT EXISTS e1(p1 string, p2 int);
 nebula> ALTER EDGE e1 ADD (p3 int, p4 string);
 nebula> ALTER EDGE e1 TTL_DURATION = 2, TTL_COL = "p2";
 nebula> ALTER EDGE e1 COMMENT = 'edge1';

diff --git a/docs-2.0/3.ngql-guide/12.vertex-statements/1.insert-vertex.md b/docs-2.0/3.ngql-guide/12.vertex-statements/1.insert-vertex.md
@@ -48,12 +48,12 @@ prop_value_list:
 
 ```ngql
 # 插入不包含属性的点。
-nebula> CREATE TAG t1();                   
+nebula> CREATE TAG IF NOT EXISTS t1();                   
 nebula> INSERT VERTEX t1() VALUE "10":(); 
 ```
 
 ```ngql
-nebula> CREATE TAG t2 (name string, age int);                
+nebula> CREATE TAG IF NOT EXISTS t2 (name string, age int);                
 nebula> INSERT VERTEX t2 (name, age) VALUES "11":("n1", 12);
 
 # 创建失败，因为"a13"不是int类型。
@@ -64,8 +64,8 @@ nebula> INSERT VERTEX t2 (name, age) VALUES "13":("n3", 12), "14":("n4", 8);
 ```
 
 ```ngql
-nebula> CREATE TAG t3(p1 int);
-nebula> CREATE TAG t4(p2 string);
+nebula> CREATE TAG IF NOT EXISTS t3(p1 int);
+nebula> CREATE TAG IF NOT EXISTS t4(p2 string);
 
 # 一次插入两个Tag的属性到同一个点。
 nebula> INSERT VERTEX  t3 (p1), t4(p2) VALUES "21": (321, "hello");
@@ -87,7 +87,7 @@ nebula> FETCH PROP ON t2 "11";
 ```
 
 ```ngql
-nebula> CREATE TAG t5(p1 fixed_string(5) NOT NULL, p2 int, p3 int DEFAULT NULL);
+nebula> CREATE TAG IF NOT EXISTS t5(p1 fixed_string(5) NOT NULL, p2 int, p3 int DEFAULT NULL);
 nebula> INSERT VERTEX t5(p1, p2, p3) VALUES "001":("Abe", 2, 3);
 
 # 插入失败，因为属性p1不能为NULL。

diff --git a/docs-2.0/3.ngql-guide/12.vertex-statements/3.upsert-vertex.md b/docs-2.0/3.ngql-guide/12.vertex-statements/3.upsert-vertex.md
@@ -105,7 +105,7 @@ nebula> UPSERT VERTEX ON player "player668" \
 上面最后一个示例中，因为`age`没有默认值，插入点时，`age`默认值为`NULL`，执行`age = age + 1`后仍为`NULL`。如果`age`有默认值，则`age = age + 1`可以正常执行，例如：
 
 ```ngql
-nebula> CREATE TAG player_with_default(name string, age int DEFAULT 20);
+nebula> CREATE TAG IF NOT EXISTS player_with_default(name string, age int DEFAULT 20);
 Execution succeeded
 
 nebula> UPSERT VERTEX ON player_with_default "player101" \

diff --git a/docs-2.0/3.ngql-guide/13.edge-statements/1.insert-edge.md b/docs-2.0/3.ngql-guide/13.edge-statements/1.insert-edge.md
@@ -45,15 +45,15 @@ INSERT EDGE [IF NOT EXISTS] <edge_type> ( <prop_name_list> ) {VALUES | VALUE}
 
 ```ngql
 # 插入不包含属性的边。
-nebula> CREATE EDGE e1();                 
+nebula> CREATE EDGE IF NOT EXISTS e1();                 
 nebula> INSERT EDGE e1 () VALUES "10"->"11":();  
 
 # 插入rank为1的边。
 nebula> INSERT EDGE e1 () VALUES "10"->"11"@1:(); 
 ```
 
 ```ngql
-nebula> CREATE EDGE e2 (name string, age int); 
+nebula> CREATE EDGE IF NOT EXISTS e2 (name string, age int); 
 nebula> INSERT EDGE e2 (name, age) VALUES "11"->"13":("n1", 1);
 
 # 一次插入2条边。

diff --git a/docs-2.0/3.ngql-guide/13.edge-statements/3.upsert-edge.md b/docs-2.0/3.ngql-guide/13.edge-statements/3.upsert-edge.md
@@ -106,7 +106,7 @@ nebula> UPSERT EDGE on serve \
 上面最后一个示例中，因为`end_year`没有默认值，插入边时，`end_year`默认值为`NULL`，执行`end_year = end_year + 1`后仍为`NULL`。如果`end_year`有默认值，则`end_year = end_year + 1`可以正常执行，例如：
 
 ```ngql
-nebula> CREATE EDGE serve_with_default(start_year int, end_year int DEFAULT 2010);
+nebula> CREATE EDGE IF NOT EXISTS serve_with_default(start_year int, end_year int DEFAULT 2010);
 Execution succeeded
 
 nebula> UPSERT EDGE on serve_with_default \

diff --git a/docs-2.0/3.ngql-guide/14.native-index-statements/1.create-native-index.md b/docs-2.0/3.ngql-guide/14.native-index-statements/1.create-native-index.md
@@ -94,31 +94,31 @@ nebula> CREATE EDGE INDEX follow_index on follow();
 ## 创建单属性索引
 
 ```ngql
-nebula> CREATE TAG INDEX player_index_0 on player(name(10));
+nebula> CREATE TAG INDEX IF NOT EXISTS player_index_0 on player(name(10));
 ```
 
 上述示例是为所有包含Tag`player`的点创建属性`name`的索引，索引长度为10。即只使用属性`name`的前10个字符来创建索引。
 
 ```ngql
 # 变长字符串需要指定索引长度。
-nebula> CREATE TAG var_string(p1 string);
-nebula> CREATE TAG INDEX var ON var_string(p1(10));
+nebula> CREATE TAG IF NOT EXISTS var_string(p1 string);
+nebula> CREATE TAG INDEX IF NOT EXISTS var ON var_string(p1(10));
 
 # 定长字符串不需要指定索引长度。
-nebula> CREATE TAG fix_string(p1 FIXED_STRING(10));
-nebula> CREATE TAG INDEX fix ON fix_string(p1);
+nebula> CREATE TAG IF NOT EXISTS fix_string(p1 FIXED_STRING(10));
+nebula> CREATE TAG INDEX IF NOT EXISTS fix ON fix_string(p1);
 ```
 
 ```ngql
-nebula> CREATE EDGE INDEX follow_index_0 on follow(degree);
+nebula> CREATE EDGE INDEX IF NOT EXISTS follow_index_0 on follow(degree);
 ```
 
 ## 创建复合属性索引
 
 `复合属性索引`用于查找一个Tag(或者Edge type)中的多个属性（的组合）。
 
 ```ngql
-nebula> CREATE TAG INDEX player_index_1 on player(name(10), age);
+nebula> CREATE TAG INDEX IF NOT EXISTS player_index_1 on player(name(10), age);
 ```
 
 !!! caution

diff --git a/docs-2.0/3.ngql-guide/14.native-index-statements/4.rebuild-native-index.md b/docs-2.0/3.ngql-guide/14.native-index-statements/4.rebuild-native-index.md
@@ -24,8 +24,8 @@ REBUILD {TAG | EDGE} INDEX [<index_name_list>];
 ## 示例
 
 ```ngql
-nebula> CREATE TAG person(name string, age int, gender string, email string);
-nebula> CREATE TAG INDEX single_person_index ON person(name(10));
+nebula> CREATE TAG IF NOT EXISTS person(name string, age int, gender string, email string);
+nebula> CREATE TAG INDEX IF NOT EXISTS single_person_index ON person(name(10));
 
 # 重建索引，返回任务ID。
 nebula> REBUILD TAG INDEX single_person_index;

diff --git a/....0/3.ngql-guide/15.full-text-index-statements/1.search-with-text-based-index.md b/....0/3.ngql-guide/15.full-text-index-statements/1.search-with-text-based-index.md
@@ -74,7 +74,7 @@ LOOKUP ON {<tag> | <edge_type>} WHERE <expression> [YIELD <return_list>];
 
 ```ngql
 //创建图空间。
-nebula> CREATE SPACE basketballplayer (partition_num=3,replica_factor=1, vid_type=fixed_string(30));
+nebula> CREATE SPACE IF NOT EXISTS basketballplayer (partition_num=3,replica_factor=1, vid_type=fixed_string(30));
 
 //登录文本搜索客户端。
 nebula> SIGN IN TEXT SERVICE (127.0.0.1:9200);
@@ -86,10 +86,10 @@ nebula> USE basketballplayer;
 nebula> ADD LISTENER ELASTICSEARCH 192.168.8.5:9789;
 
 //创建Tag。
-nebula> CREATE TAG player(name string, age int);
+nebula> CREATE TAG IF NOT EXISTS player(name string, age int);
 
 //创建原生索引。
-nebula> CREATE TAG INDEX name ON player(name(20));
+nebula> CREATE TAG INDEX IF NOT EXISTS name ON player(name(20));
 
 //重建原生索引。
 nebula> REBUILD TAG INDEX;

diff --git a/docs-2.0/3.ngql-guide/16.subgraph-and-path/1.get-subgraph.md b/docs-2.0/3.ngql-guide/16.subgraph-and-path/1.get-subgraph.md
@@ -33,12 +33,12 @@ GET SUBGRAPH [WITH PROP] [<step_count> STEPS] FROM {<vid>, <vid>...}
 插入测试数据：
 
 ```ngql
-nebula> CREATE SPACE subgraph(partition_num=15, replica_factor=1, vid_type=fixed_string(30));
+nebula> CREATE SPACE IF NOT EXISTS subgraph(partition_num=15, replica_factor=1, vid_type=fixed_string(30));
 nebula> USE subgraph;
-nebula> CREATE TAG player(name string, age int);
-nebula> CREATE TAG team(name string);
-nebula> CREATE EDGE follow(degree int);
-nebula> CREATE EDGE serve(start_year int, end_year int);
+nebula> CREATE TAG IF NOT EXISTS player(name string, age int);
+nebula> CREATE TAG IF NOT EXISTS team(name string);
+nebula> CREATE EDGE IF NOT EXISTS follow(degree int);
+nebula> CREATE EDGE IF NOT EXISTS serve(start_year int, end_year int);
 nebula> INSERT VERTEX player(name, age) VALUES "player100":("Tim Duncan", 42);
 nebula> INSERT VERTEX player(name, age) VALUES "player101":("Tony Parker", 36);
 nebula> INSERT VERTEX player(name, age) VALUES "player102":("LaMarcus Aldridge", 33);

diff --git a/docs-2.0/3.ngql-guide/3.data-types/10.geography.md b/docs-2.0/3.ngql-guide/3.data-types/10.geography.md
@@ -28,19 +28,19 @@ geo相关函数请参见[geo函数](../6.functions-and-expressions/14.geo.md)。
 
 ```ngql
 //创建Tag，允许存储任意形状地理位置数据类型。
-nebula> CREATE TAG any_shape(geo geography);
+nebula> CREATE TAG IF NOT EXISTS any_shape(geo geography);
 
 //创建Tag，只允许存储点形状地理位置数据类型。
-nebula> CREATE TAG only_point(geo geography(point));
+nebula> CREATE TAG IF NOT EXISTS only_point(geo geography(point));
 
 //创建Tag，只允许存储线段形状地理位置数据类型。
-nebula> CREATE TAG only_linestring(geo geography(linestring));
+nebula> CREATE TAG IF NOT EXISTS only_linestring(geo geography(linestring));
 
 //创建Tag，只允许存储多边形形状地理位置数据类型。
-nebula> CREATE TAG only_polygon(geo geography(polygon));
+nebula> CREATE TAG IF NOT EXISTS only_polygon(geo geography(polygon));
 
 //创建Edge type，允许存储任意形状地理位置数据类型。
-nebula> CREATE EDGE any_shape_edge(geo geography);
+nebula> CREATE EDGE IF NOT EXISTS any_shape_edge(geo geography);
 
 //创建存储多边形地理位置的点。
 nebula> INSERT VERTEX any_shape(geo) VALUES "103":(ST_GeogFromText("POLYGON((0 1, 1 2, 2 3, 0 1))"));
@@ -65,7 +65,7 @@ nebula> FETCH PROP ON any_shape_edge "201"->"302" YIELD ST_ASText(any_shape_edge
 +---------------------+---------------------+----------------------+---------------------------------+
 
 //为geo属性创建索引并使用LOOKUP查询。
-nebula> CREATE TAG INDEX any_shape_geo_index ON any_shape(geo);
+nebula> CREATE TAG INDEX IF NOT EXISTS any_shape_geo_index ON any_shape(geo);
 nebula> REBUILD TAG INDEX any_shape_geo_index;
 nebula> LOOKUP ON any_shape YIELD ST_ASText(any_shape.geo);
 +----------+-------------------------------------------------+

diff --git a/docs-2.0/3.ngql-guide/3.data-types/3.string.md b/docs-2.0/3.ngql-guide/3.data-types/3.string.md
@@ -24,13 +24,13 @@ nGQL支持以如下方式使用字符串：
 - 将属性值的类型定义为定长字符串
 
     ```ngql
-    nebula> CREATE TAG t1 (p1 FIXED_STRING(10)); 
+    nebula> CREATE TAG IF NOT EXISTS t1 (p1 FIXED_STRING(10)); 
     ```
 
 - 将属性值的类型定义为变长字符串
 
     ```ngql
-    nebula> CREATE TAG t2 (p2 STRING); 
+    nebula> CREATE TAG IF NOT EXISTS t2 (p2 STRING); 
     ```
 
 如果尝试写入的定长字符串超出长度限制：

diff --git a/docs-2.0/3.ngql-guide/3.data-types/4.date-and-time.md b/docs-2.0/3.ngql-guide/3.data-types/4.date-and-time.md
@@ -77,7 +77,7 @@
 1. 创建Tag，名称为`date1`，包含`DATE`、`TIME`和`DATETIME`三种类型。
 
     ```ngql
-    nebula> CREATE TAG date1(p1 date, p2 time, p3 datetime);
+    nebula> CREATE TAG IF NOT EXISTS date1(p1 date, p2 time, p3 datetime);
     ```
 
 2. 插入点，名称为`test1`。
@@ -89,7 +89,7 @@
 3. 获取`test1`的属性`p1`的月份。
 
     ```ngql
-    nebula> CREATE TAG INDEX date1_index ON date1(p1);
+    nebula> CREATE TAG INDEX IF NOT EXISTS date1_index ON date1(p1);
     nebula> REBUILD TAG INDEX date1_index;
     nebula> MATCH (v:date1) RETURN v.p1.month;
     +------------+
@@ -102,7 +102,7 @@
 4. 创建Tag，名称为`school`，包含`TIMESTAMP`类型。
 
     ```ngql
-    nebula> CREATE TAG school(name string , found_time timestamp);
+    nebula> CREATE TAG IF NOT EXISTS school(name string , found_time timestamp);
     ```
 
 5. 插入点，名称为`DUT`，存储时间为`"1988-03-01T08:00:00"`。

diff --git a/docs-2.0/3.ngql-guide/3.data-types/5.null.md b/docs-2.0/3.ngql-guide/3.data-types/5.null.md
@@ -37,7 +37,7 @@ Nebula Graph中，对NULL的操作以及返回结果不兼容openCypher。
 创建Tag，名称为`player`，指定属性`name`为`NOT NULL`。
 
 ```ngql
-nebula> CREATE TAG player(name string NOT NULL, age int);
+nebula> CREATE TAG IF NOT EXISTS player(name string NOT NULL, age int);
 ```
 
 使用`SHOW`命令查看创建Tag语句，属性`name`为`NOT NULL`，属性`age`为默认的`NULL`。
@@ -65,7 +65,7 @@ nebula> INSERT VERTEX player(name, age) VALUES "Kobe":("Kobe",null);
 创建Tag，名称为`player`，指定属性`age`为`NOT NULL`，并设置默认值`18`。
 
 ```ngql
-nebula> CREATE TAG player(name string, age int NOT NULL DEFAULT 18);
+nebula> CREATE TAG IF NOT EXISTS player(name string, age int NOT NULL DEFAULT 18);
 ```
 
 插入点`Kobe`，只设置属性`name`。

diff --git a/docs-2.0/3.ngql-guide/7.general-query-statements/2.match.md b/docs-2.0/3.ngql-guide/7.general-query-statements/2.match.md
@@ -44,8 +44,8 @@ MATCH <pattern> [<WHERE clause>] RETURN <output>;
 
 ```ngql
 # 在Tag player的name属性和Edge type follow上创建索引。
-nebula> CREATE TAG INDEX name ON player(name(20));
-nebula> CREATE EDGE INDEX follow_index on follow();
+nebula> CREATE TAG INDEX IF NOT EXISTS name ON player(name(20));
+nebula> CREATE EDGE INDEX IF NOT EXISTS follow_index on follow();
 
 # 重建索引使其生效。
 nebula> REBUILD TAG INDEX name;